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  • How to Export/Transfer DHCP data ?

    - by sreevatsa
    We have a very old server HP ML110 its giving hardware ( Power )trouble and we are hosting DHCP services on this on windows 2000 . Now i would like to transfer all the DHCP data ( it has reserved IP ) from this old server to a new server which is win2003 . How do i do ?

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  • After turning off my monitor, the computer won't display again

    - by Nick Lassonde
    If I physically turn off the monitor (DVI connection) and then turn it back on, the connection does not wake back up. The monitor enters "Power Saving" mode. I've tried unplugging the DVI cable and plugging back in, I've tried updating the video card drivers (it's Windows Vista; Windows 7 failed to install on this machine). I can use VNC to connect to the machine again, and after a reboot, the monitor works again. Does anyone have any idea?

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  • How can I minimize the amount my router slows down my Internet connection speed?

    - by Lord Torgamus
    Background I'm working with what I assume is a pretty common Internet setup: a cable modem, a wireless router and a few Internet-connected devices. Lately, I've started being more demanding on my Internet connection, and noticed that using my router slows down my download speeds considerably. I just kind of dealt with it until Zune Marketplace on the Xbox 360 told me that a movie was going to take well over ten hours to download, and I just didn't want to wait that long. Good little scientist that I am, I tried to reduce the problem down to one variable. The test As a control, I turned off all the devices in the house that use wireless Internet, and unplugged all the wired devices except for the Xbox. I also power-cycled both the modem and the router. I then tried to download the movie again, and was told that it would still take over ten hours. Next, I unplugged the router, and connected the Xbox directly to the modem. The movie downloaded in just over one hour. As far as I can tell, this means that my ISP, other cable users near me, the remote servers, anything wireless-related and my machines' disk speeds can't be at fault. A similar experiment that replaced the Xbox with a wired laptop produced similar results. To me, this says "the router is responsible for things taking around ten times longer to download." My question I'd still prefer to use the router for a few reasons: it's a pain to connect and disconnect everything every time there's a big file to download direct connection to the modem isn't good for security only one machine can be connected directly to the modem at a time What can I do to have fast connection speeds while still using the router? I don't mind turning other machines off, as long as I don't have to mess with power and ethernet cables. EDIT : After asking this followup question and then this one, I installed dd-wrt on my router, and I seem to be getting higher and more consistent speeds. Perhaps more importantly, my memory use is fairly constant. I know this isn't an answer — which is why I'm not posting it as an answer — but it is how I resolved the situation, and hopefully it'll be helpful for someone.

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  • New laptop battery: 80% capacity

    - by Danilo
    I have got an old laptop (HP Pavilion DV2000, 5.5 years old) and I just bought a new battery for it (10,8V 5200mAh 6 Cells) probably not an original one. When I charged it full the first time, it reached a capacity (as see through the Ubuntu 12.04 Power Statistics tool) of 80%. After 3 full cycles, it's at 79.5%. Do you think it is normal, or the battery may be damaged (and I can complain with the vendor)?

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  • VMWare Player does not save changes in guest operating system

    - by Giorgos Manoltzas
    I have installed VMWare Player in my Windows 7 Ultimate and I have added Ubuntu 12.10 in a virtual machine. The problem is that every time I power off the virtual machine everything is lost. I mean every program I install or folder i save or anything else is lost completely. And when I start the again the virtual machine is like newly installed. Is there an option to change this (strange) behaviour?

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  • Secure Standalone Server Plus Firewall Unit [closed]

    - by orbitron
    We need to send a 2U server, 1U UPS and 1U firewall to a third-party. The thing is, it needs to be a secured case (locked unit) that has proper airflow and we can have power and networking cables coming out of the back. We've googled far and wide and have only been able to find 'hard case' units that offer some level of security but they are extremely bulky and require freight delivery. Thank you for any insight or solutions.

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  • UITableview has problem reloading

    - by seelani
    Hi guys, I've kinda finished my application for a school project but have run into a major "bug". It's a account management application. I'm unable to insert a picture here so here's a link: http://i232.photobucket.com/albums/ee112/seelani/Screenshot2010-12-22atPM075512.png Here's the problem when i click on the plus sign, i push a nav controller to load another view to handle the adding and deleting of categories. When i add and return back to the view above, it doesn't update. It only updates after i hit the button on the right which is another view used to change some settings, and return back to the page. I did some research on viewWillAppear and such but I'm still confused to why it doesn't work properly. This problem is also affecting my program when i delete a category, and return back to this view it crashes cos the view has not reloaded successfully. I will get this error when deleting and returning to the view. "* Terminating app due to uncaught exception 'NSRangeException', reason: '* -[NSMutableArray objectAtIndex:]: index 4 beyond bounds [0 .. 3]'". [EDIT] Table View Code: @class LoginViewController; @implementation CategoryTableViewController @synthesize categoryTableViewController; @synthesize categoryArray; @synthesize accountsTableViewController; @synthesize editAccountTable; @synthesize window; CategoryMgmtTableController *categoryMgmtTableController; ChangePasswordView *changePasswordView; - (void) save_Clicked:(id)sender { /* UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Category Management" message:@"Load category management table view" delegate:self cancelButtonTitle: @"OK" otherButtonTitles:nil]; [alert show]; [alert release]; */ KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; categoryMgmtTableController = [[CategoryMgmtTableController alloc]initWithNibName:@"CategoryMgmtTable" bundle:nil]; [appDelegate.categoryNavController pushViewController:categoryMgmtTableController animated:YES]; } - (void) change_Clicked:(id)sender { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Change Password" message:@"Change password View" delegate:self cancelButtonTitle: @"OK" otherButtonTitles:nil]; [alert show]; [alert release]; KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; changePasswordView = [[ChangePasswordView alloc]initWithNibName:@"ChangePasswordView" bundle:nil]; [appDelegate.categoryNavController pushViewController:changePasswordView animated:YES]; /* KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; categoryMgmtTableController = [[CategoryMgmtTableController alloc]initWithNibName:@"CategoryMgmtTable" bundle:nil]; [appDelegate.categoryNavController pushViewController:categoryMgmtTableController animated:YES]; */ } #pragma mark - #pragma mark Initialization /* - (id)initWithStyle:(UITableViewStyle)style { // Override initWithStyle: if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. if ((self = [super initWithStyle:style])) { } return self; } */ -(void) initializeCategoryArray { sqlite3 *db= [KeyCryptAppAppDelegate getNewDBConnection]; KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; const char *sql = [[NSString stringWithFormat:(@"Select Category from Categories;")]cString]; const char *cmd = [[NSString stringWithFormat:@"pragma key = '%@' ", appDelegate.pragmaKey]cString]; sqlite3_stmt *compiledStatement; sqlite3_exec(db, cmd, NULL, NULL, NULL); if (sqlite3_prepare_v2(db, sql, -1, &compiledStatement, NULL)==SQLITE_OK) { while(sqlite3_step(compiledStatement) == SQLITE_ROW) [categoryArray addObject:[NSString stringWithUTF8String:(char*) sqlite3_column_text(compiledStatement, 0)]]; } else { NSAssert1(0,@"Error preparing statement", sqlite3_errmsg(db)); } sqlite3_finalize(compiledStatement); } #pragma mark - #pragma mark View lifecycle - (void)viewDidLoad { // Uncomment the following line to display an Edit button in the navigation bar for this view controller. // self.navigationItem.rightBarButtonItem = self.editButtonItem; [super viewDidLoad]; } - (void)viewWillAppear:(BOOL)animated { self.title = NSLocalizedString(@"Categories",@"Types of Categories"); categoryArray = [[NSMutableArray alloc]init]; [self initializeCategoryArray]; self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(save_Clicked:)] autorelease]; self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(change_Clicked:)] autorelease]; [super viewWillAppear:animated]; } - (void)viewDidAppear:(BOOL)animated { NSLog (@"view did appear"); [super viewDidAppear:animated]; } - (void)viewWillDisappear:(BOOL)animated { NSLog (@"view will disappear"); [super viewWillDisappear:animated]; } - (void)viewDidDisappear:(BOOL)animated { [categoryTableView reloadData]; NSLog (@"view did disappear"); [super viewDidDisappear:animated]; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ #pragma mark - #pragma mark Table view data source - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { // Return the number of sections. return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { // Return the number of rows in the section. return [self.categoryArray count]; } // Customize the appearance of table view cells. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } // Configure the cell... NSUInteger row = [indexPath row]; cell.text = [categoryArray objectAtIndex:row]; cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator; return cell; } /* // Override to support conditional editing of the table view. - (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath { // Return NO if you do not want the specified item to be editable. return YES; } */ /* // Override to support editing the table view. - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the row from the data source [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES]; } else if (editingStyle == UITableViewCellEditingStyleInsert) { // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view } } */ /* // Override to support rearranging the table view. - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath { } */ /* // Override to support conditional rearranging of the table view. - (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath { // Return NO if you do not want the item to be re-orderable. return YES; } */ #pragma mark - #pragma mark Table view delegate - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSString *selectedCategory = [categoryArray objectAtIndex:[indexPath row]]; NSLog (@"AccountsTableView.xib is called."); if ([categoryArray containsObject: selectedCategory]) { if (self.accountsTableViewController == nil) { AccountsTableViewController *aAccountsView = [[AccountsTableViewController alloc]initWithNibName:@"AccountsTableView"bundle:nil]; self.accountsTableViewController =aAccountsView; [aAccountsView release]; } NSInteger row =[indexPath row]; accountsTableViewController.title = [NSString stringWithFormat:@"%@", [categoryArray objectAtIndex:row]]; // This portion pushes the categoryNavController. KeyCryptAppAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; [self.accountsTableViewController initWithTextSelected:selectedCategory]; KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; appDelegate.pickedCategory = selectedCategory; [delegate.categoryNavController pushViewController:accountsTableViewController animated:YES]; } } #pragma mark - #pragma mark Memory management - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Relinquish ownership any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Relinquish ownership of anything that can be recreated in viewDidLoad or on demand. // For example: self.myOutlet = nil; } - (void)dealloc { [accountsTableViewController release]; [super dealloc]; } @end And the code that i used to delete rows(this is in a totally different tableview): - (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { // Delete the row from the data source NSString *selectedCategory = [categoryArray objectAtIndex:indexPath.row]; [categoryArray removeObjectAtIndex:indexPath.row]; [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:YES]; [deleteCategoryTable reloadData]; //NSString *selectedCategory = [categoryArray objectAtIndex:indexPath.row]; sqlite3 *db= [KeyCryptAppAppDelegate getNewDBConnection]; KeyCryptAppAppDelegate *appDelegate = (KeyCryptAppAppDelegate *)[[UIApplication sharedApplication] delegate]; const char *sql = [[NSString stringWithFormat:@"Delete from Categories where Category = '%@';", selectedCategory]cString]; const char *cmd = [[NSString stringWithFormat:@"pragma key = '%@' ", appDelegate.pragmaKey]cString]; sqlite3_stmt *compiledStatement; sqlite3_exec(db, cmd, NULL, NULL, NULL); if (sqlite3_prepare_v2(db, sql, -1, &compiledStatement, NULL)==SQLITE_OK) { sqlite3_exec(db,sql,NULL,NULL,NULL); } else { NSAssert1(0,@"Error preparing statement", sqlite3_errmsg(db)); } sqlite3_finalize(compiledStatement); } else if (editingStyle == UITableViewCellEditingStyleInsert) { // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view } }

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  • Cross-platform distributed fault-tolerant (disconnected operation/local cache) filesystem

    - by Adrian Frühwirth
    We are facing a design "challenge" where we are required to set up a storage solution with the following properties: What we need HA a scalable storage backend offline/disconnected operation on the client to account for network outages cross-platform access client-side access from certainly Windows (probably XP upwards), possibly Linux backend integrates with AD/LDAP (permission management (user/group management, ...)) should work reasonably well over slow WAN-links Another problem is that we don't really know all possible use cases here, if people need to be able to have concurrent access to shared files or if they will only be accessing their own files, so a possible solution needs to account for concurrent access and how conflict management would look in this case from a user's point of view. This two years old blog posts sums up the impression that I have been getting during the last couple of days of research, that there are lots of current übercool projects implementing (non-Windows) clustered petabyte-capable blob-storage solutions but that there is none that supports disconnected operation nicely and natively, but I am hoping that we have missed an obvious solution. What we have tried OpenAFS We figured that we want a distributed network filesystem with a local cache and tested OpenAFS (which, as the only currently "stable" DFS supporting disconnected operation, seemed the way to go) for a week but there are several problems with it: it's a real pain to set up there are no official RHEL/CentOS packages the package of the current stable version 1.6.5.1 from elrepo randomly kernel panics on fresh installs, this is an absolute no-go Windows support (including the required Kerberos packages) is mystical. The current client for the 1.6 branch does not run on Windows 8, the current client for the 1.7 does but it just randomly crashes. After that experience we didn't even bother testing on XP and Windows 7. Suffice to say, we couldn't get it working and the whole setup has been so unstable and complicated to setup that it's just not an option for production. Samba + Unison Since OpenAFS was a complete disaster and no other DFS seems to support disconnected operation we went for a simpler idea that would sync files against a Samba server using Unison. This has the following advantages: Samba integrates with ADs; it's a pain but can be done. Samba solves the problem of remotely accessing the storage from Windows but introduces another SPOF and does not address the actual storage problem. We could probably stick any clustered FS underneath Samba, but that means we need a HA Samba setup on top of that to maintain HA which probably adds a lot of additional complexity. I vaguely remember trying to implement redundancy with Samba before and I could not silently failover between servers. Even when online, you are working with local files which will result in more conflicts than would be necessary if a local cache were only touched when disconnected It's not automatic. We cannot expect users to manually sync their files using the (functional, but not-so-pretty) GTK GUI on a regular basis. I attempted to semi-automate the process using the Windows task scheduler, but you cannot really do it in a satisfactory way. On top of that, the way Unison works makes syncing against Samba a costly operation, so I am afraid that it just doesn't scale very well or even at all. Samba + "Offline Files" After that we became a little desparate and gave Windows "offline files" a chance. We figured that having something that is inbuilt into the OS would reduce administrative efforts, helps blaming someone else when it's not working properly and should just work since people have been using this for years. Right? Wrong. We really wanted it to work, but it just doesn't. 30 minutes of copying files around and unplugging network cables/disabling network interfaces left us with (silent! there is only a tiny notification in Windows explorer in the statusbar, which doesn't even open Sync Center if you click on it!) undeletable files on the server (!) and conflicts that should not even be conflicts. In the end, we had one successful sync of a tiny text file, everything else just exploded horribly. Beyond that, there are other problems: Microsoft admits that "offline files" in Windows XP cannot cope with "large files" and therefore does not cache/sync them at all which would mean those files become unavailable if the connection drop In Windows 7 the feature is only available in the Professional/Ultimate/Enterprise editions. Summary Unless there is another fault-tolerant DFS that supports Windows natively I assume that stacking a HA Samba cluster on top of something like GlusterFS/Lustre/whatnot is the only option, but I hope that I am wrong here. How do other companies allow fault-tolerant network access to redundant storage in a heterogeneous environment with Windows?

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  • Simple Observation in Django: How Can I Correctly Modify The `attrs` sent to __new__ of a Django Mod

    - by DGGenuine
    Hello, I'm a strong proponent of the observer pattern, and this is what I'd like to be able to do in my Django models.py: class AModel(Model): __metaclass__ = SomethingMagical @post_save(AnotherModel) @classmethod def observe_another_model_saved(klass, sender, instance, created, **kwargs): pass @pre_init('YetAnotherModel') @classmethod def observe_yet_another_model_initializing(klass, sender, *args, **kwargs): pass @post_delete('DifferentApp.SomeModel') @classmethod def observe_some_model_deleted(klass, sender, **kwargs): pass This would connect a signal with sender = the decorator's argument and receiver = the decorated method. Right now my signal connection code all exists in __init__.py which is okay, but a little unmaintainable. I want this code all in one place, the models.py file. Thanks to helpful feedback from the community I'm very close (I think.) (I'm using a metaclass solution instead of the class decorator solution in the previous question/answer because you can't set attributes on classmethods, which I need.) I am having a strange error I don't understand. At the end of my post are the contents of a models.py that you can pop into a fresh project/application to see the error. Set your database to sqlite and add the application to installed apps. This is the error: Validating models... Unhandled exception in thread started by Traceback (most recent call last): File "/Library/Python/2.6/site-packages//lib/python2.6/site-packages/django/core/management/commands/runserver.py", line 48, in inner_run File "/Library/Python/2.6/site-packages/django/core/management/base.py", line 253, in validate raise CommandError("One or more models did not validate:\n%s" % error_text) django.core.management.base.CommandError: One or more models did not validate: local.myothermodel: 'my_model' has a relation with model MyModel, which has either not been installed or is abstract. I've indicated a few different things you can comment in/out to fix the error. First, if you don't modify the attrs sent to the metaclass's __new__, then the error does not arise. (Note even if you copy the dictionary element by element into a new dictionary, it still fails; only using the exact attrs dictionary works.) Second, if you reference the first model by class rather than by string, the error also doesn't arise regardless of what you do in __new__. I appreciate your help. I'll be githubbing the solution if and when it works. Maybe other people would enjoy a simplified way to use Django signals to observe application happenings. #models.py from django.db import models from django.db.models.base import ModelBase from django.db.models import signals import pdb class UnconnectedMethodWrapper(object): sender = None method = None signal = None def __init__(self, signal, sender, method): self.signal = signal self.sender = sender self.method = method def post_save(sender): return _make_decorator(signals.post_save, sender) def _make_decorator(signal, sender): def decorator(view): return UnconnectedMethodWrapper(signal, sender, view) return decorator class ConnectableModel(ModelBase): """ A meta class for any class that will have static or class methods that need to be connected to signals. """ def __new__(cls, name, bases, attrs): unconnecteds = {} ## NO WORK newattrs = {} for name, attr in attrs.iteritems(): if isinstance(attr, UnconnectedMethodWrapper): unconnecteds[name] = attr newattrs[name] = attr.method #replace the UnconnectedMethodWrapper with the method it wrapped. else: newattrs[name] = attr ## NO WORK # newattrs = {} # for name, attr in attrs.iteritems(): # newattrs[name] = attr ## WORKS # newattrs = attrs new = super(ConnectableModel, cls).__new__(cls, name, bases, newattrs) for name, unconnected in unconnecteds.iteritems(): _connect_signal(unconnected.signal, unconnected.sender, getattr(new, name), new._meta.app_label) return new def _connect_signal(signal, sender, receiver, default_app_label): # full implementation also accepts basestring as sender and will look up model accordingly signal.connect(sender=sender, receiver=receiver) class MyModel(models.Model): __metaclass__ = ConnectableModel @post_save('In my application this string matters') @classmethod def observe_it(klass, sender, instance, created, **kwargs): pass @classmethod def normal_class_method(klass): pass class MyOtherModel(models.Model): ## WORKS # my_model = models.ForeignKey(MyModel) ## NO WORK my_model = models.ForeignKey('MyModel')

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  • ASP.net roles and Projects

    - by Zyphrax
    EDIT - Rewrote my original question to give a bit more information Background info At my work I'm working on a ASP.Net web application for our customers. In our implementation we use technologies like Forms authentication with MembershipProviders and RoleProviders. All went well until I ran into some difficulties with configuring the roles, because the roles aren't system-wide, but related to the customer accounts and projects. I can't name our exact setup/formula, because I think our company wouldn't approve that... What's a customer / project? Our company provides management information for our customers on a yearly (or other interval) basis. In our systems a customer/contract consists of: one Account: information about the Company per Account, one or more Products: the bundle of management information we'll provide per Product, one or more Measurements: a period of time, in which we gather and report the data Extranet site setup Eventually we want all customers to be able to access their management information with our online system. The extranet consists of two sites: Company site: provides an overview of Account information and the Products Measurement site: after selecting a Measurement, detailed information on that period of time The measurement site is the most interesting part of the extranet. We will create submodules for new overviews, reports, managing and maintaining resources that are important for the research. Our Visual Studio solution consists of a number of projects. One web application named Portal for the basis. The sites and modules are virtual directories within that application (makes it easier to share MasterPages among things). What kind of roles? The following users (read: roles) will be using the system: Admins: development users :) (not customer related, full access) Employees: employees of our company (not customer related, full access) Customer SuperUser: top level managers (full access to their account/measurement) Customer ContactPerson: primary contact (full access to their measurement(s)) Customer Manager: a department manager (limited access, specific data of a measurement) What about ASP.Net users? The system will have many ASP.Net users, let's focus on the customer users: Users are not shared between Accounts SuperUser X automatically has access to all (and new) measurements User Y could be Primary contact for Measurement 1, but have no role for Measurement 2 User Y could be Primary contact for Measurement 1, but have a Manager role for Measurement 2 The department managers are many individual users (per Measurement), if Manager Z had a login for Measurement 1, we would like to use that login again if he participates in Measurement 2. URL structure These are typical urls in our application: http://host/login - the login screen http://host/project - the account/product overview screen (measurement selection) http://host/project/1000 - measurement (id:1000) details http://host/project/1000/planning - planning overview (for primary contact/superuser) http://host/project/1000/reports - report downloads (manager department X can only access report X) We will also create a document url, where you can request a specific document by it's GUID. The system will have to check if the user has rights to the document. The document is related to a Measurement, the User or specific roles have specific rights to the document. What's the problem? (finally ;)) Roles aren't enough to determine what a user is allowed to see/access/download a specific item. It's not enough to say that a certain navigation item is accessible to Managers. When the user requests Measurement 1000, we have to check that the user not only has a Manager role, but a Manager role for Measurement 1000. Summarized: How can we limit users to their accounts/measurements? (remember superusers see all measurements, some managers only specific measurements) How can we apply roles at a product/measurement level? (user X could be primarycontact for measurement 1, but just a manager for measurement 2) How can we limit manager access to the reports screen and only to their department's reports? All with the magic of asp.net classes, perhaps with a custom roleprovider implementation. Similar Stackoverflow question/problem http://stackoverflow.com/questions/1367483/asp-net-how-to-manage-users-with-different-types-of-roles

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  • Mbean registered but not found in mbean Server

    - by Prisco
    I have a problem about the mbeans. I have created a simple mbean and I have registered it on the default mBeanServer that is run (Via eclipse or java -jar mbean.jar) and in the same process if I try to fouund the mbean registered with a simple query: for (ObjectInstance instance : mbs.queryMBeans(ObjectNameMbean, null)) { System.out.println(instance.toString()); } the query retuerns my mbean, but if I start another process and try to search this mbean registered the mbeas is not found! why? The approch is : (Process that is running) public static void main(String[] args) throws Exception { MBeanServer mbeanServer =ManagementFactory.getPlatformMBeanServer(); ObjectName objectName = new ObjectName(ObjectNameMbean); Simple simple = new Simple (1, 0); mbeanServer.registerMBean(simple, objectName); while (true) { wait (Is this necessary?) } } So this is the first process that is running (that has the only pourpose to registry the mbean, because there is another process that want to read these informations. So I start another process to search this mbean but nothing. I 'm not using jboss but the local Java virtual Machine but my scope is to deploy this simple application in one ejb (autostart) and another ejb will read all informations. All suggestions are really apprecciated. This example should be more useful : Object Hello: public class Hello implements HelloMBean { public void sayHello() { System.out.println("hello, world"); } public int add(int x, int y) { return x + y; } public String getName() { return this.name; } public int getCacheSize() { return this.cacheSize; } public synchronized void setCacheSize(int size) { this.cacheSize = size; System.out.println("Cache size now " + this.cacheSize); } private final String name = "Reginald"; private int cacheSize = DEFAULT_CACHE_SIZE; private static final int DEFAULT_CACHE_SIZE = 200; } Interface HelloBean (implemented by Hello) public interface HelloMBean { public void sayHello(); public int add(int x, int y); public String getName(); public int getCacheSize(); public void setCacheSize(int size); } Simple Main import java.lang.management.ManagementFactory; import java.util.logging.Logger; import javax.management.MBeanServer; import javax.management.ObjectName; public class Main { static Logger aLog = Logger.getLogger("MBeanTest"); public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); Hello mbean = new Hello(); mbs.registerMBean(mbean, name); // System.out.println(mbs.getAttribute(name, "Name")); aLog.info("Waiting forever..."); Thread.sleep(Long.MAX_VALUE); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } } So now I have exported this project as jar file and run it as "java -jar helloBean.jar" and by eclipse I have modified the main class to read informations of this read (Example "Name" attribute) by using the same objectname used to registry it . Main to read : public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); System.out.println(mbs.getAttribute(name, "Name")); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } But nothing, the bean is not found.

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  • AGENT: The World's Smartest Watch

    - by Rob Chartier
    AGENT: The World's Smartest Watch by Secret Labs + House of Horology Disclaimer: Most if not all of this content has been gleaned from the comments on the Kickstarter project page and comments section. Any discrepancies between this post and any documentation on agentwatches.com, kickstarter.com, etc.., those official sites take precedence. Overview The next generation smartwatch with brand-new technology. World-class developer tools, unparalleled battery life, Qi wireless charging. Kickstarter Page, Comments Funding period : May 21, 2013 - Jun 20, 2013 MSRP : $249 Other Urls http://www.agentwatches.com/ https://www.facebook.com/agentwatches http://twitter.com/agentwatches http://pinterest.com/agentwatches/ http://paper.li/robchartier/1371234640 Developer Story The first official launch of the preview SDK and emulator will happen on 20-Jun-2013.  All development will be done in Visual Studio 2012, using the .NET Micro Framework SDK 2.3.  The SDK will ship with the first round of the expected API for developers along with an emulator. With that said, there is no need to wait for the SDK.  You can download the tooling now and get started with Apps and Faces immediately.  The only thing that you will not be able to work with is the API; but for example, watch faces, you can start building the basic face rendering with the Bitmap graphics drawing in the .NET Micro Framework.   Does it look good? Before we dig into any more of the gory details, here are a few photos of the current available prototype models.   The watch on the tiny QI Charter   If you wander too far away from your phone, your watch will let you know with a vibration and a message, all but one button will dismiss the message.   An app showing the premium weather data!   Nice stitching on the straps, leather and silicon will be available, along with a few lengths to choose from (short, regular, long lengths). On to those gory details…. Hardware Specs Processor 120MHz ARM Cortex-M4 processor (ATSAM4SD32) with secondary AVR co-processor Flash & RAM 2MB of onboard flash and 160KB of RAM 1/4 of the onboard flash will be used by the OS The flash is permanent (non-volatile) storage. Bluetooth Bluetooth 4.0 BD/EDR + LE Bluetooth 4.0 is backwards compatible with Bluetooth 2.1, so classic Bluetooth functions (BD/EDR, SPP/AVRCP/PBAP/etc.) will work fine. Sensors 3D Accelerometer (Motion) ST LSM303DLHC Ambient Light Sensor Hardware power metering Vibration Motor (You can pulse it to create vibration patterns, not sure about the vibration strength - driven with PWM) No piezo/speaker or microphone. Other QI Wireless Charging, no NFC, no wall adapter included Custom LED Backlight No GPS in the watch. It uses the GPS in your phone. AGENT watch apps are deployed and debugged wirelessly from your PC via Bluetooth. RoHS, Pb-free Battery Expected to use a CR2430-sized rechargeable battery – replaceable (Mouser, Amazon) Estimated charging time from empty is 2 hours with provided charger 7 Days typical with Bluetooth on, 30 days with Bluetooth off (watch-face only mode) The battery should last at least 2 years, with 100s of charge cycles. Physical dimensions Roughly 38mm top-to-bottom on the front face 35mm left-to-right on the front face and around 12mm in depth 22mm strap Two ~1/16" hex screws to attach the watch pin The top watchcase material candidates are PVD stainless steel, brushed matte ceramic, and high-quality polycarbonate (TBD). The glass lens is mineral glass, Anti-glare glass lens Strap options Leather and silicon straps will be available Expected to have three sizes Display 1.28" Sharp Memory Display The display stays on 100% of the time. Dimensions: 128x128 pixels Buttons Custom "Pusher" buttons, they will not make noise like a mouse click, and are very durable. The top-left button activates the backlight; bottom-left changes apps; three buttons on the right are up/select/down and can be used for custom purposes by apps. Backup reset procedure is currently activated by holding the home/menu button and the top-right user button for about ten seconds Device Support Android 2.3 or newer iPhone 4S or newer Windows Phone 8 or newer Heart Rate monitors - Bluetooth SPP or Bluetooth LE (GATT) is what you'll want the heart monitor to support. Almost limitless Bluetooth device support! Internationalization & Localization Full UTF8 Support from the ground up. AGENT's user interface is in English. Your content (caller ID, music tracks, notifications) will be in your native language. We have a plan to cover most major character sets, with Latin characters pre-loaded on the watch. Simplified Chinese will be available Feature overview Phone lost alert Caller ID Music Control (possible volume control) Wireless Charging Timer Stopwatch Vibrating Alarm (possibly custom vibrations for caller id) A few default watch faces Airplane mode (by demand or low power) Can be turned off completely Customizable 3rd party watch faces, applications which can be loaded over bluetooth. Sample apps that maybe installed Weather Sample Apps not installed Exercise App Other Possible Skype integration over Bluetooth. They will provide an AGENT app for your smartphone (iPhone, Android, Windows Phone). You'll be able to use it to load apps onto the watch.. You will be able to cancel phone calls. With compatible phones you can also answer, end, etc. They are adopting the standard hands-free profile to provide these features and caller ID.

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  • Understanding and Controlling Parallel Query Processing in SQL Server

    Data warehousing and general reporting applications tend to be CPU intensive because they need to read and process a large number of rows. To facilitate quick data processing for queries that touch a large amount of data, Microsoft SQL Server exploits the power of multiple logical processors to provide parallel query processing operations such as parallel scans. Through extensive testing, we have learned that, for most large queries that are executed in a parallel fashion, SQL Server can deliver linear or nearly linear response time speedup as the number of logical processors increases. However, some queries in high parallelism scenarios perform suboptimally. There are also some parallelism issues that can occur in a multi-user parallel query workload. This white paper describes parallel performance problems you might encounter when you run such queries and workloads, and it explains why these issues occur. In addition, it presents how data warehouse developers can detect these issues, and how they can work around them or mitigate them.

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  • Parallelism in .NET – Part 16, Creating Tasks via a TaskFactory

    - by Reed
    The Task class in the Task Parallel Library supplies a large set of features.  However, when creating the task, and assigning it to a TaskScheduler, and starting the Task, there are quite a few steps involved.  This gets even more cumbersome when multiple tasks are involved.  Each task must be constructed, duplicating any options required, then started individually, potentially on a specific scheduler.  At first glance, this makes the new Task class seem like more work than ThreadPool.QueueUserWorkItem in .NET 3.5. In order to simplify this process, and make Tasks simple to use in simple cases, without sacrificing their power and flexibility, the Task Parallel Library added a new class: TaskFactory. The TaskFactory class is intended to “Provide support for creating and scheduling Task objects.”  Its entire purpose is to simplify development when working with Task instances.  The Task class provides access to the default TaskFactory via the Task.Factory static property.  By default, TaskFactory uses the default TaskScheduler to schedule tasks on a ThreadPool thread.  By using Task.Factory, we can automatically create and start a task in a single “fire and forget” manner, similar to how we did with ThreadPool.QueueUserWorkItem: Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This provides us with the same level of simplicity we had with ThreadPool.QueueUserWorkItem, but even more power.  For example, we can now easily wait on the task: // Start our task on a background thread var task = Task.Factory.StartNew(() => this.ExecuteBackgroundWork(myData) ); // Do other work on the main thread, // while the task above executes in the background this.ExecuteWorkSynchronously(); // Wait for the background task to finish task.Wait(); TaskFactory simplifies creation and startup of simple background tasks dramatically. In addition to using the default TaskFactory, it’s often useful to construct a custom TaskFactory.  The TaskFactory class includes an entire set of constructors which allow you to specify the default configuration for every Task instance created by that factory.  This is particularly useful when using a custom TaskScheduler.  For example, look at the sample code for starting a task on the UI thread in Part 15: // Given the following, constructed on the UI thread // TaskScheduler uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // When inside a background task, we can do string status = GetUpdatedStatus(); (new Task(() => { statusLabel.Text = status; })) .Start(uiScheduler); This is actually quite a bit more complicated than necessary.  When we create the uiScheduler instance, we can use that to construct a TaskFactory that will automatically schedule tasks on the UI thread.  To do that, we’d create the following on our main thread, prior to constructing our background tasks: // Construct a task scheduler from the current SynchronizationContext (UI thread) var uiScheduler = TaskScheduler.FromCurrentSynchronizationContext(); // Construct a new TaskFactory using our UI scheduler var uiTaskFactory = new TaskFactory(uiScheduler); If we do this, when we’re on a background thread, we can use this new TaskFactory to marshal a Task back onto the UI thread.  Our previous code simplifies to: // When inside a background task, we can do string status = GetUpdatedStatus(); // Update our UI uiTaskFactory.StartNew( () => statusLabel.Text = status); Notice how much simpler this becomes!  By taking advantage of the convenience provided by a custom TaskFactory, we can now marshal to set data on the UI thread in a single, clear line of code!

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  • Discoverer 11g 11.1.1.2 Certified with EBS 12 on Five New Platforms

    - by Steven Chan
    Oracle Fusion Middleware 11g Release 1 includes Oracle Discoverer.  Discoverer is an ad-hoc query, reporting, analysis, and Web-publishing tool that allows end-users to work directly with Oracle E-Business Suite OLTP data.We certified Discoverer 11gR1 11.1.1.2 with the E-Business Suite Release 11i and 12 on Linux earlier this year.  Our Applications Platforms Group has just released five additional platform certifications for Discoverer 11.1.1.2 for Oracle E-Business Suite Release 12 (12.0.x and 12.1.x).Certified EBS 12 PlatformsLinux x86-64 (Oracle Enterprise Linux 4, 5) Linux x86-64 (RHEL 4, 5) Linux x86-64 (SLES 10) Oracle Solaris on SPARC (64-bit) (Solaris 9, 10) HP-UX Itanium (11.23, 11.31) HP-UX PA-RISC (64-bit) (11.23, 11.31) IBM AIX on Power Systems (64-bit) (5.3, 6.1) Microsoft Windows Server (32-bit) (2003, 2008)

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  • SQL Server and Hyper-V Dynamic Memory Part 2

    - by SQLOS Team
    Part 1 of this series was an introduction and overview of Hyper-V Dynamic Memory. This part looks at SQL Server memory management and how the SQL engine responds to changing OS memory conditions.   Part 2: SQL Server Memory Management As with any Windows process, sqlserver.exe has a virtual address space (VAS) of 4GB on 32-bit and 8TB in 64-bit editions. Pages in its VAS are mapped to pages in physical memory when the memory is committed and referenced for the first time. The collection of VAS pages that have been recently referenced is known as the Working Set. How and when SQL Server allocates virtual memory and grows its working set depends on the memory model it uses. SQL Server supports three basic memory models:   1. Conventional Memory Model   The Conventional model is the default SQL Server memory model and has the following properties: - Dynamic - can grow or shrink its working set in response to load and external (operating system) memory conditions. - OS uses 4K pages – (not to be confused with SQL Server “pages” which are 8K regions of committed memory).- Pageable - Can be paged out to disk by the operating system.   2. Locked Page Model The locked page memory model is set when SQL Server is started with "Lock Pages in Memory" privilege*. It has the following characteristics: - Dynamic - can grow or shrink its working set in the same way as the Conventional model.- OS uses 4K pages - Non-Pageable – When memory is committed it is locked in memory, meaning that it will remain backed by physical memory and will not be paged out by the operating system. A common misconception is to interpret "locked" as non-dynamic. A SQL Server instance using the locked page memory model will grow and shrink (allocate memory and release memory) in response to changing workload and OS memory conditions in the same way as it does with the conventional model.   This is an important consideration when we look at Hyper-V Dynamic Memory – “locked” memory works perfectly well with “dynamic” memory.   * Note in “Denali” (Standard Edition and above), and in SQL 2008 R2 64-bit (Enterprise and above editions) the Lock Pages in Memory privilege is all that is required to set this model. In 2008 R2 64-Bit standard edition it also requires trace flag 845 to be set, in 2008 R2 32-bit editions it requires sp_configure 'awe enabled' 1.   3. Large Page Model The Large page model is set using trace flag 834 and potentially offers a small performance boost for systems that are configured with large pages. It is characterized by: - Static - memory is allocated at startup and does not change. - OS uses large (>2MB) pages - Non-Pageable The large page model is supported with Hyper-V Dynamic Memory (and Hyper-V also supports large pages), but you get no benefit from using Dynamic Memory with this model since SQL Server memory does not grow or shrink. The rest of this article will focus on the locked and conventional SQL Server memory models.   When does SQL Server grow? For “dynamic” configurations (Conventional and Locked memory models), the sqlservr.exe process grows – allocates and commits memory from the OS – in response to a workload. As much memory is allocated as is required to optimally run the query and buffer data for future queries, subject to limitations imposed by:   - SQL Server max server memory setting. If this configuration option is set, the buffer pool is not allowed to grow to more than this value. In SQL Server 2008 this value represents single page allocations, and in “Denali” it represents any size page allocations and also managed CLR procedure allocations.   - Memory signals from OS. The operating system sets a signal on memory resource notification objects to indicate whether it has memory available or whether it is low on available memory. If there is only 32MB free for every 4GB of memory a low memory signal is set, which continues until 64MB/4GB is free. If there is 96MB/4GB free the operating system sets a high memory signal. SQL Server only allocates memory when the high memory signal is set.   To summarize, for SQL Server to grow you need three conditions: a workload, max server memory setting higher than the current allocation, high memory signals from the OS.    When does SQL Server shrink caches? SQL Server as a rule does not like to return memory to the OS, but it will shrink its caches in response to memory pressure. Memory pressure can be divided into “internal” and “external”.   - External memory pressure occurs when the operating system is running low on memory and low memory signals are set. The SQL Server Resource Monitor checks for low memory signals approximately every 5 seconds and it will attempt to free memory until the signals stop.   To free memory SQL Server does the following: ·         Frees unused memory. ·         Notifies Memory Manager Clients to release memory o   Caches – Free unreferenced cache objects. o   Buffer pool - Based on oldest access times.   The freed memory is released back to the operating system. This process continues until the low memory resource notifications stop.    - Internal memory pressure occurs when the size of different caches and allocations increase but the SQL Server process needs to keep its total memory within a target value. For example if max server memory is set and certain caches are growing large, it will cause SQL to free memory for re-use internally, but not to release memory back to the OS. If you lower the value of max server memory you will generate internal memory pressure that will cause SQL to release memory back to the OS.    Memory pressure handling has not changed much since SQL 2005 and it was described in detail in a blog post by Slava Oks.   Note that SQL Server Express is an exception to the above behavior. Unlike other editions it does not assume it is the most important process running on the system but tries to be more “desktop” friendly. It will empty its working set after a period of inactivity.   How does SQL Server respond to changing OS memory?    In SQL Server 2005 support for Hot-Add memory was introduced. This feature, available in Enterprise and above editions, allows the server to make use of any extra physical memory that was added after SQL Server started. Being able to add physical memory when the system is running is limited to specialized hardware, but with the Hyper-V Dynamic Memory feature, when new memory is allocated to a guest virtual machine, it looks like hot-add physical memory to the guest. What this means is that thanks to the hot-add memory feature, SQL Server 2005 and higher can dynamically grow if more “physical” memory is granted to a guest VM by Hyper-V dynamic memory.   SQL Server checks OS memory every second and dynamically adjusts its “target” (based on available OS memory and max server memory) accordingly.   In “Denali” Standard Edition will also have sqlserver.exe support for hot-add memory when running virtualized (i.e. detecting and acting on Hyper-V Dynamic Memory allocations).   How does a SQL Server workload in a guest VM impact Hyper-V dynamic memory scheduling?   When a SQL workload causes the sqlserver.exe process to grow its working set, the Hyper-V memory scheduler will detect memory pressure in the guest VM and add memory to it. SQL Server will then detect the extra memory and grow according to workload demand. In our tests we have seen this feedback process cause a guest VM to grow quickly in response to SQL workload - we are still working on characterizing this ramp-up.    How does SQL Server respond when Hyper-V removes memory from a guest VM through ballooning?   If pressure from other VM's cause Hyper-V Dynamic Memory to take memory away from a VM through ballooning (allocating memory with a virtual device driver and returning it to the host OS), Windows Memory Manager will page out unlocked portions of memory and signal low resource notification events. When SQL Server detects these events it will shrink memory until the low memory notifications stop (see cache shrinking description above).    This raises another question. Can we make SQL Server release memory more readily and hence behave more "dynamically" without compromising performance? In certain circumstances where the application workload is predictable it may be possible to have a job which varies "max server memory" according to need, lowering it when the engine is inactive and raising it before a period of activity. This would have limited applicaability but it is something we're looking into.   What Memory Management changes are there in SQL Server “Denali”?   In SQL Server “Denali” (aka SQL11) the Memory Manager has been re-written to be more efficient. The main changes are summarized in this post. An important change with respect to Hyper-V Dynamic Memory support is that now the max server memory setting includes any size page allocations and managed CLR procedure allocations it now represents a closer approximation to total sqlserver.exe memory usage. This makes it easier to calculate a value for max server memory, which becomes important when configuring virtual machines to work well with Hyper-V Dynamic Memory Startup and Maximum RAM settings.   Another important change is no more AWE or hot-add support for 32-bit edition. This means if you're running a 32-bit edition of Denali you're limited to a 4GB address space and will not be able to take advantage of dynamically added OS memory that wasn't present when SQL Server started (though Hyper-V Dynamic Memory is still a supported configuration).   In part 3 we’ll develop some best practices for configuring and using SQL Server with Dynamic Memory. Originally posted at http://blogs.msdn.com/b/sqlosteam/

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  • CodePlex Daily Summary for Friday, March 05, 2010

    CodePlex Daily Summary for Friday, March 05, 2010New Projects.svn Folders Cleanup Tool: dotSVN Cleanup is a tool that allows you to remove the .svn folders . Just click, browse, say abracadabra ...and the magic is done. Have fun with...Accord: The Accord framework creates an easy we to integrate any Dependency Injection framework into your project, while abstracting the details of your im...Asp.net MVC Lab: Try asp.net mvc outASP.NET Themes management with Webforms: The provided source is an example for how to use themes in ASP.NET Webforms. this source is the "up to date" support for the article I wroteB&W Port Scanner: B&W Port Scanner (formerly Net Inspector) is a fast TCP Port scan utility. The main idea is support of customizable operations to be performed f...BizTalk SWAT - Simple Web Activity Tracker: This is a web based version of BizTalk HAT. The concept is designed to be able to share and enable sharing of orchestration info easily. Some of th...C# Linear Hash Table: A C# dictionary-like implementation of a linear hash table. It is more memory efficiant than the .NET dictionary, and also almost as fast. NOTE: On...DBF Import Export Wizard: DBF Import Export Wizard is a tool for anyone needing to import DBF files into SQL Server or to export SQL Server tables to a DBF file. This proje...Domain as XML - Driven Development: Visual Studio Code Samples: Domain as XML - Driven Development: Visual Studio Code SamplesEasyDownload: This application allows to manage downloads handling an stack of files and several useful configurationsEos2: .FlightTickets: This application allows to buy flight ticketsFotofly PhotoViewer: A Silverlight control that uses the Fotofly metadata library to show the people in a photo (using Windows Live Photo Gallery People metadata) and a...Fujiy source code: Source code examplesGameSet: This application allows to play games with distributed users.Injectivity (Dependency Injection): Injectivity is a dependency injection framework (written in C#) with a strong focus on the ease of configuration and performance. Having been writt...Inventory: Keep track of inputs, materias and salesLoanTin.Com Source Code: LoanTin.Com - a Social Networking Website as same as Tumblr.com, based on source code of Loantiner Project, allow anyone can share anything to anyo...mysln: my solutions.NumTextBox: TextBox控件重写 之NumTextBox,主要实现的功能是,只允许输入数字,或String,Numeric,Currency,Decimal,Float,Double,Short,Int,Long 修改自:http://www.codeproject.com/KB/edit/num...Quick Performance Monitor: This small utility helps to monitor performance counters without using the full blown perfmon tool from Windows. It supports a number of command li...Runo: Runo ResearchSales: This application allows to manage a hardware storeScrewWiki Form Auth Provider: Enables your ASP.NET site to use Forms Authentication to integrate with your ScrewWiki. User management is performed on a parent site, and cookie i...SDS: Scientific DataSet library and tools: The SDS library makes it easy for .Net developers to read, write and share scalars, vectors, matrices and multidimensional grids which are very com...ShapeSweeper: Minesweeper-like game for the Zune HD. Each hidden object has three properties to discover--location, color, and shape--and all three must be corre...SilverlightExcel: an Excel file viewer in Silverlight 4: SilverlightExcel is a Silverlight application allowing you to open and view Excel files and also create graphs.sPWadmin: pwAdmin is an Web Interface based on JSP that uses the PW-Java API to control an PW-Server.Video Player control in Silverlight: A control for playing video in Silverlight 4 with chapters on timeline control. This player will be easily skinnable and customizable. More Featur...XNA Light Pre Pass Renderer: A demo/sample that shows how to write a light pre pass renderer in XNA.Zimms: Collaboration Site for friends, a code depot, and scratch padNew Releases.svn Folders Cleanup Tool: dotSVN Cleanup Tool: dotSVN Cleanup Tool executableAccord: Alpha: Initial build of the Accord framework.AcPrac: AcPrac Ver 0.1: The first version of AcPrac. It is not fully functional, but rather a version to get the bugs out. Please report all bugs.ASP.NET: ASP.NET Browser Definition Files: This download contains: ASP.NET 4 Browser Definition Files -- You can use the new ASP.NET 4 browser definition files with earlier versions of ASP....B&W Port Scanner: Black`n`White Port Scanner 1.0: B&W Port Scanner 1.0 Final Release Date: 03.03.2010 Black`n`WhiteBizTalk SWAT - Simple Web Activity Tracker: BizTalk SWAT: This is a web based version of BizTalk HAT. The concept is designed to be able to share and enable sharing of orchestration info easily. It uses th...BTP Tools: CSB+CUV+HCSB dict files 2010-03-04: 5. is now missing a space between the Strong’s number and the Count: >CSB Translation: 圣所 7, 至圣所G39+G394 it should be: CSB Translation: 圣所 7, 至圣所G...C# Linear Hash Table: Linear Hash Table: First working version of the Linear Hash Table.Cassiopeia: WinTools 1.0 beta: First ReleaseComposure: Caliburn-44007-trunk-vs2010.net40: This is a very simple conversion of the Caliburn trunk (rev 44007) for use in Visual Studio 2010 RC1 built against .NET40. Because the conversion w...Cover Creator: CoverCreator 1.3.0: English and Polish version. Functionality to add image to the front page. Load / save covers.DBF Import Export Wizard: DBF Import Export Wizard Source Code: Version 0.1.0.3DBF Import Export Wizard: DBF_Import_Export_Wizard Setup 0.1.0.3: Zip file contains Setup.exeESB Toolkit Extensions: Tellago BizTalk ESB 2.0 Toolkit Extensions v0.2: Windows Installer file that installs Library on a BizTalk ESB 2.0 system. This Install automatically configures the esb.config to use the new compo...Fotofly PhotoViewer: Fotofly Photoview v0.1: The first public release. Based on a Silverlight application I have been using for over a year at www.tassography.com. This version uses Fotofly v0...HPC with GPUs applied to CG: Cuda Soft Bodies simulation: Cuda src for soft bodiesHPC with GPUs applied to CG: Full Soft Bodies src: full src code for soft bodies simulationInjectivity (Dependency Injection): 2.8.166.2135: Release 2.8.166.2135 of the Injectivity dependency injection framework.Line Counter: 1.5 (Code Outline Preview): This version contains preview of the code outline feature, you can now view C# code outline within Line Counter. Note that the code outline now onl...Micajah Mindtouch Deki Wiki Copier: MicajahWikiCopier: You should use the following line arguments: WikiCopier.exe "http://oldwikiwithdata.wik.is/@api/deki" "login" "password" "http://newwiki.somename.l...ncontrols: Alpha 0.4.0.1: Added some example on the Console Project.NumTextBox: NumTextBox初始版本: TextBox控件重写 之NumTextBox,主要实现的功能是,只允许输入数字,或String,Numeric,Currency,Decimal,Float,Double,Short,Int,Long 此为初始版本PSCodeplex: PS CodePlex 0.2: PS CodePlex 0.2 has some breaking changes to the parameters. A few of the parameters are renamed and a few are made as switch parameters. Add-Rele...Quick Performance Monitor: QPerfMon First release - Version 1.0.0: The first release of the utility.RapidWebDev - .NET Enterprise Software Development Infrastructure: ProductManagement Quick Sample 0.2: This is a sample product management application to demonstrate how to develop enterprise software in RapidWebDev. The glossary of the system are ro...ScrewWiki Form Auth Provider: ScrewWiki Forms Authentication: Initial ReleaseSee.Sharper: See.Sharper.Docs-1.10.3.4: HTML documentation (including Doxygen project)See.Sharper: See.Sharper-1.10.3.4: Solution (Source files, debug and release binaries)Solar.Generic: Solar.Generic 0.8.0.0 Beta (Revised, Renamed): Solar.Generic 0.8.0.0 (Revised & Renamed) Renamed project from Solar.Commons to Solar.Generic. Project solution file is now in format of Visual ...Solar.Security: Solar.Security 1.1.0.0: Performed several major refactorings of code base. Stripped In-Memory implementation of IConfiguration interface of transactional behavior due to...sPWadmin: pwAdmin v0.7: -Star System Simulator: Star System Simulator 2.3: Changes in this release: Fixed several localisation issues. Features in this release: Model star systems in 3D. Euler-Cromer method. Improved...SysI: sysi, stable and ready: This time for sure.TheWhiteAmbit: TheWhiteAmbit - Demo: Two little demos demonstrating: - fast realtime raytracing - generating bent normals for shading (CUDA capable GPU needed = nVidia GeForce >8x00)VsTortoise - a TortoiseSVN add-in for Microsoft Visual Studio: VsTortoise Build 22 Beta: Build 22 (beta) New: Visual Studio 2010 RC support (VsTortoise for Visual Studio 2010 RC screenshots) New: VsTortoise integrates in to Solution E...WinMergeFS: WinMergeFS 0.1.42128alpha: WinMergeFS provides AuFS functionality for windows. With WinMergeFS users can mount multiple directories into a virtual drive. Plugin based root se...WSDLGenerator: WSDLGenerator 0.0.0.2: - Bugs fixed - Code refactored - Added support for custom typesXNA Light Pre Pass Renderer: LightPrePassRendererXNA: Zipped source code for the light pre pass renderer made with XNA.Most Popular ProjectsMetaSharpRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)LiveUpload to FacebookASP.NETMicrosoft SQL Server Community & SamplesMost Active ProjectsUmbraco CMSRawrBlogEngine.NETSDS: Scientific DataSet library and toolsMapWindow GISpatterns & practices – Enterprise LibraryjQuery Library for SharePoint Web ServicesIonics Isapi Rewrite FilterMDT Web FrontEndDiffPlex - a .NET Diff Generator

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • Ubuntu 10.10 Mouse and Keyboard Freeze

    - by Kev
    I installed Ubuntu 10.10 today and have had mouse problem since. Symptoms: At some arbitrary point in time (frequency: 2-3 times per hour), the mouse and keyboard stops working for ever(may be). I start System monitor, I found out network was shutdown just before mouse freeze. Some time my keyboard keep typing one key. For example:77777777777777777777777777777777777777777777777777777.....(it keep typing for 20 sec) I found out a script just solve the freeze problem:(I hit Powerbutton) -----------------/etc/acpi/powerbtn.sh------------------------ event=button[ /]power action=/usr/sbin/fix_mouse.sh -----------------/usr/sbin/fix_mouse.sh------------------------ rmmod psmouse modprobe psmouse Yesterday I install Ubuntu 10.04 FAILED also have mouse problem. When I switch back to Windows XP. The network card is down. It kept connecting and disconnecting 1 time per sec. CPU: i5 Motherboard: ASUS P7P55D OS: Windows XP + Ubuntu 10.10 Video Card: ATI 5770 Mouse,Keyboard: PS/2

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  • Dell Latitude E6520 overheating

    - by Wu Yi Han
    I'm a newcomer to Ubuntu 11.10. My laptop is a Dell Latitude E6520, Sandy Bridge platform. The system cooling fan is crazy all the time. I don't do any intensive tasks. I really hope my laptop doesn't become a mushroom cloud. I suppose there's no perfect way to solve this... Can I lower the CPU frequency? Jupiter 0.0.51 was installed (power save mode). Cooling worked in my Windows 7 system until I deleted it. (I won't go back to Windows 7.)

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  • Diagnose PC Hardware Problems with an Ubuntu Live CD

    - by Trevor Bekolay
    So your PC randomly shuts down or gives you the blue screen of death, but you can’t figure out what’s wrong. The problem could be bad memory or hardware related, and thankfully the Ubuntu Live CD has some tools to help you figure it out. Test your RAM with memtest86+ RAM problems are difficult to diagnose—they can range from annoying program crashes, or crippling reboot loops. Even if you’re not having problems, when you install new RAM it’s a good idea to thoroughly test it. The Ubuntu Live CD includes a tool called Memtest86+ that will do just that—test your computer’s RAM! Unlike many of the Live CD tools that we’ve looked at so far, Memtest86+ has to be run outside of a graphical Ubuntu session. Fortunately, it only takes a few keystrokes. Note: If you used UNetbootin to create an Ubuntu flash drive, then memtest86+ will not be available. We recommend using the Universal USB Installer from Pendrivelinux instead (persistence is possible with Universal USB Installer, but not mandatory). Boot up your computer with a Ubuntu Live CD or USB drive. You will be greeted with this screen: Use the down arrow key to select the Test memory option and hit Enter. Memtest86+ will immediately start testing your RAM. If you suspect that a certain part of memory is the problem, you can select certain portions of memory by pressing “c” and changing that option. You can also select specific tests to run. However, the default settings of Memtest86+ will exhaustively test your memory, so we recommend leaving the settings alone. Memtest86+ will run a variety of tests that can take some time to complete, so start it running before you go to bed to give it adequate time. Test your CPU with cpuburn Random shutdowns – especially when doing computationally intensive tasks – can be a sign of a faulty CPU, power supply, or cooling system. A utility called cpuburn can help you determine if one of these pieces of hardware is the problem. Note: cpuburn is designed to stress test your computer – it will run it fast and cause the CPU to heat up, which may exacerbate small problems that otherwise would be minor. It is a powerful diagnostic tool, but should be used with caution. Boot up your computer with a Ubuntu Live CD or USB drive, and choose to run Ubuntu from the CD or USB drive. When the desktop environment loads up, open the Synaptic Package Manager by clicking on the System menu in the top-left of the screen, then selecting Administration, and then Synaptic Package Manager. Cpuburn is in the universe repository. To enable the universe repository, click on Settings in the menu at the top, and then Repositories. Add a checkmark in the box labeled “Community-maintained Open Source software (universe)”. Click close. In the main Synaptic window, click the Reload button. After the package list has reloaded and the search index has been rebuilt, enter “cpuburn” in the Quick search text box. Click the checkbox in the left column, and select Mark for Installation. Click the Apply button near the top of the window. As cpuburn installs, it will caution you about the possible dangers of its use. Assuming you wish to take the risk (and if your computer is randomly restarting constantly, it’s probably worth it), open a terminal window by clicking on the Applications menu in the top-left of the screen and then selection Applications > Terminal. Cpuburn includes a number of tools to test different types of CPUs. If your CPU is more than six years old, see the full list; for modern AMD CPUs, use the terminal command burnK7 and for modern Intel processors, use the terminal command burnP6 Our processor is an Intel, so we ran burnP6. Once it started up, it immediately pushed the CPU up to 99.7% total usage, according to the Linux utility “top”. If your computer is having a CPU, power supply, or cooling problem, then your computer is likely to shutdown within ten or fifteen minutes. Because of the strain this program puts on your computer, we don’t recommend leaving it running overnight – if there’s a problem, it should crop up relatively quickly. Cpuburn’s tools, including burnP6, have no interface; once they start running, they will start driving your CPU until you stop them. To stop a program like burnP6, press Ctrl+C in the terminal window that is running the program. Conclusion The Ubuntu Live CD provides two great testing tools to diagnose a tricky computer problem, or to stress test a new computer. While they are advanced tools that should be used with caution, they’re extremely useful and easy enough that anyone can use them. Similar Articles Productive Geek Tips Reset Your Ubuntu Password Easily from the Live CDCreate a Persistent Bootable Ubuntu USB Flash DriveAdding extra Repositories on UbuntuHow to Share folders with your Ubuntu Virtual Machine (guest)Building a New Computer – Part 3: Setting it Up TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Have Fun Editing Photo Editing with Citrify Outlook Connector Upgrade Error Gadfly is a cool Twitter/Silverlight app Enable DreamScene in Windows 7 Microsoft’s “How Do I ?” Videos Home Networks – How do they look like & the problems they cause

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  • Oracle Fusion Applications: Changing the Game

    - by kellsey.ruppel(at)oracle.com
    Originally posted in the Oracle Profit Magazine, November 2010 Edition. When the order processing system red-flags a customer's credit status, the IT department doesn't get the customer's call. When a supplier misses a delivery date for a key automotive assembly, it's not the CIO who has to answer for the error. Knowledge workers (known in IT circles as "users") are on the front lines when an exception occurs in an established business process. They're also the ones who study sales trends to decide when to open a new store in an up-and-coming neighborhood, which products are most profitable, how employee skill sets are evolving, and which suppliers are most efficient. In short, knowledge workers are masters of business as unusual. Traditional enterprise resource planning (ERP) systems and other familiar enterprise applications excel at automating, managing, and executing standard business processes. These programs shine when everything goes as planned. Life gets even trickier when a traditional application needs to be extended with a new service or an extra step is added to a business process when new products are brought to market, divisions are merged, or companies are acquired. Monolithic applications often need the IT department to step in and make the necessary adjustments--incurring additional costs and delays. Until now. When Oracle unveiled the much-anticipated family of Oracle Fusion Applications at Oracle OpenWorld in September 2010, knowledge workers in particular had a lot to cheer about. Business users will soon have ready access to analytical information and collaboration tools in the context of what they are working on, so they can make better decisions when problems or opportunities arise. Additionally, the Oracle Fusion Applications platform will make it easy for business users to tweak processes, create new capabilities, and find information, often without the need for IT department assistance and while still following company guidelines. And IT leaders will be happy to hear about new deployment options, guided implementation and setup tools, and cost-saving management capabilities. Just as important, the underlying technologies in Oracle Fusion Applications will allow organizations to choose among their existing investments and next-generation enterprise applications so they can introduce innovations at a pace that makes the most business and financial sense. "Oracle Fusion Applications are architected so you don't have to do rip and replace," says Jim Hayes, managing director of the consulting firm Accenture. "That's very important for creating a business case that will get through the steering committee and be approved by the board. It shows you can drive value and make a difference in the near term." For these and other reasons, analysts and early adopters are calling Oracle Fusion Applications a game changer for enterprise customers. The differences become apparent in three key areas: the way we innovate, work, and adopt technology. Game Changer #1: New Standard for InnovationChange is a constant challenge for most businesses, whether the catalysts are market dynamics, new competition, or the ever-expanding regulatory environment. And, in an ongoing effort to differentiate, business leaders are constantly looking for new ways to do business, serve constituents, and bring new products and services to market. In addition, companies face significant costs to keep their applications up-to-date. For example, when a company adds new suppliers to a procurement system, the IT shop typically has to invest time, effort, and even consulting fees for custom integrations that allow various ERP systems to communicate with each other. Oracle Fusion Applications were built on Web services and a modular SOA foundation to ease customizations and integration activities among all applications--whether from Oracle or another vendor. Interfaces and updates written in ubiquitous Java, rather than a proprietary coding language, allow organizations to tap into existing in-house technical skills rather than seek expensive outside specialists. And with SOA, organizations can extend a feature set or integrate with other SOA environments by combining Web services such as "look up customer" into a new business process managed by the BPEL orchestration engine. Flexibility like this has long-term implications. "Because users capture these changes at a higher metadata layer, not in the application's code, changes and additions are protected even as new versions of Oracle Fusion Applications are released," says Steve Miranda, senior vice president of applications development at Oracle. "This is a much more sustainable approach because you don't incur costly customizations that prevent upgrades and other innovations." And changes are easier to make: if one change is made in the metadata, that change is automatically reflected throughout the application interface, business intelligence, business process, and business logic. Game Changer #2: New Standard for WorkBoosting productivity comes down to doing the basics right: running business processes more efficiently and managing exceptions more effectively, so users can accomplish more in the course of a day or spend more quality time with the most profitable customers. The fastest way to improve process efficiency is to reduce the number of steps it takes to execute common tasks, such as ordering office equipment from an internal procurement system. Oracle Fusion Applications will deliver a complete role-based user experience with business intelligence and collaboration capabilities provided in the context of the work at hand. "We created every Oracle Fusion Applications screen by asking 'What does the user need to know?' 'What does he or she need to do?' and 'Who do they need to work with to get the job done?'" Miranda explains. So when the sales department heads need new laptops, the self-service procurement screen will not only display a list of approved vendors and configurations, but also a running list of reviews by coworkers who recently purchased the various models. Embedded intelligence may also display prevailing delivery lead times based on actual order histories, not the generic shipping dates vendors may quote. The pervasive business intelligence serves many other business activities across all areas of the enterprise. For example, a manager considering whether to promote a direct report can see the person's employee profile, with a salary history, appraisal summaries, and a rundown of skills and training. This approach to business intelligence also has implications for supply chain management. "One of the challenges at Ingersoll Rand is lack of visibility in our supply chain," says Mike Macrie, global director of enterprise applications for global industrial firm Ingersoll Rand. "Oracle Fusion Applications are going to provide the embedded intelligence to give us that visibility and give us the ability to analyze those orders at any point in our supply chain." Oracle Fusion Applications will also create a "role-based user experience" that displays a work list of events that need attention, based on user job function. Role awareness guides users with daily lists of action items and exceptions. So a credit manager may see seven invoices with discounts that are about to expire or 12 suppliers that have been put on hold because credit memos are awaiting approval. Individualization extends to the search capabilities of Oracle Fusion Applications. The platform uses Web-style search screens powered by an Oracle enterprise search engine, with a security framework that filters search results so individuals will only see the internal information they're authorized to access. A further aid to productivity is Oracle Fusion Applications' integration with Web 2.0 collaboration and social networking resources for business environments. Hover-over text will reveal relevant contact information whenever the name of a person appears in an Oracle Fusion Application. Users can connect via an online chat, phone call, or instant message without leaving the main application, reducing the time required for an accounts payable staffer to resolve a mismatch between an invoiced charge and the service record, for example. Addresses of suppliers, customers, or partners will also initiate hover-over text to show contact details and Web-based maps. Finally, Oracle Fusion Applications will promote a new way of working with purpose-driven communities that can bring new efficiencies to everything from cultivating sales leads to managing new projects. As soon as a lead or project materializes, the applications will automatically gather relevant participants into an online community that shares member contact information, schedules, discussion forums, and Wiki pages. "Oracle Fusion Applications will allow us to take it to the next level with embedded Web 2.0 tools and the embedded analytics," says Steve Printz, CIO and vice president, supply chain management, at window-and-door manufacturer Pella. "[This] allows those employees today who are processing transactions to really contribute to the success of the company and become decision-makers." Game Changer #3: New Standard for Technology AdoptionAs IT becomes a dominant component of how businesses run and compete, organizations need to lower the cost of implementing applications and introducing new application features. In the past, rolling out new code often required creating a test bed system, moving beta code to a separate system for user feedback, and--once all the revisions were made--moving version one of the software onto production systems, where business users could finally get the needed new features. Oracle Fusion Applications will use a dedicated setup manager application to streamline this process. First, the setup manager will help scope out the project, querying users about their requirements. "From those questions and answers we determine the steps and the order of those steps that will enable that task," Miranda says. Next, system utilities will assign tasks to owners, track completion status, and monitor the overall status of a programming effort. Oracle Fusion Applications can then recommend Web services that allow users to migrate setup choices and steps across all the various deployments of the application. Those setup capabilities automate the migration from test systems to production systems, as well as between different business units that may be using the same application. "The self-service ability of the setup manager helps business users change setups with very little intervention from the IT team," says Ravi Kumar, vice president at IT services company Infosys. "That to me is a big difference from how we've viewed enterprise applications before." For additional flexibility, organizations will be able to adopt Oracle Fusion Applications modules in either of two modes: a single-instance alternative uses one database for all Oracle Fusion Applications, while a "pillar mode" creates separate databases to underpin each application. This means IT departments running any one of Oracle's applications or even third-party applications can plug Oracle Fusion Applications modules into their environment and see additional business value created on top of their existing systems. And Oracle Fusion Applications offer a hybrid approach to deployment. The applications are all software-as-a-service-ready, so customers can choose on-premises, public or private cloud, or a combination of these to suit their business needs. It's that combination of flexibility and a roadmap for the future that may be the biggest game changer of all. "The Oracle Fusion Applications architecture allows us to migrate our company at a pace that's consistent with our business strategy, whereas before we might have had to do it with a massive upgrade," says Macrie of Ingersoll Rand. "We're looking forward to that architecture to really give us more flexibility in how we migrate over time." For More InformationUser Input Key to the Success of Oracle Fusion ApplicationsTransforming Coexistence into Strategic ValueUnder the HoodOracle Fusion ApplicationsOracle Service-Oriented Architecture  

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  • Ubuntu 12.04 installation problem

    - by LittleLego
    Okay, at the beginning of the installation, it went well. My laptop is connected to power source, the internet, I have also checked the boxes "install updates while installation", "install third party plugin". After inputting location, keyboard layout info and user's details and password, the installation took place. But after 3/4 of the installation, it stopped, right above the progress bar, it displayed "installing system", I clicked on the arrow below it, the terminal-like screen also stopped carrying out the process. I then clicked on the "Skip" button, nothing happens. I thought it was the problem of my laptop, then I did another fresh installation, same thing happened. The terminal-like screen was showing some different words. But it's not an error message, just some installation info. Does anyone have valuable solution to this problem?

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