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• Excel export displaying '#####...'

  - by Cypher

  I'm trying to export an Excel database into .txt (Tab Delimited), but some of my cells are quite large. When I export into a txt some of the cells are exported as '#######....' which is surprisingly useless. Has this happened to anyone else? Do you know an easy fix? Data from one cell of my column: Accounting, African Studies, Agricultural/Bioresource Engineering, Agricultural Economics, Agricultural Science, Anatomy/Cell Biology, Animal Biology, Animal Science, Anthropology, Applied Zoology, Architecture, Art History, Atmospheric/Oceanic Science, Biochemistry, Biology, Botanical Sciences, Canadian Studies, Chemical Engineering, Chemistry/Bio-Organic/Environmental/Materials,ChurchMusicPerformance, Civil Engineering/Applied Mechanics, Classics, Composition, Computer Engineering,ComputerScience, ContemporaryGerman Studies, Dietetics, Early Music Performance, Earth/Planetary Sciences, East Asian Studies, Economics, Electrical Engineering, English Literature/ Drama/Theatre/Cultural Studies, Entrepreneurship, Environment, Environmental Biology, Finance, Food Science, Foundations of Computing, French Language/Linguistics/Literature/Translation, Geography, Geography/ Urban Systems, German, German Language/Literature/Culture, Hispanic Languages/Literature/Culture,History,Humanistic Studies, Industrial Relations, Information Systems, International Business, International Development Studies, Italian Studies/Medieval/Renaissance, Jazz Performance, Jewish Studies, Keyboard Studies, Kindergarten/Elementary Education, Kindergarten/Elementary Education/Jewish Studies,Kinesiology, Labor/Management Relations, Latin American/Caribbean Studies, Linguistics, Literature/Translation, Management Science, Marketing, Materials Engineering,Mathematics,Mathematics/Statistics,Mechanical Engineering, Microbiology, Microbiology/Immunology, Middle Eastern Studies, Mining Engineering, Music, Music Education, MusicHistory,Music Technology,Music Theory,North American Studies, Nutrition,OperationsManagement,OrganizationalBehavior/Human Resources Management, Performing Arts, Philosophy, Physical Education, Physics, Physiology, Plant Sciences, Political Science, Psychology, Quebec Studies, Religious Studies/Scriptures/Interpretations/World Religions,ResourceConservation,Russian, Science for Teachers,Secondary Education, Secondary Education/Music, Secondary Education/Science, SocialWork, Sociology, Software Engineering, Soil Science, Strategic Management, Teaching of French/English as a Second Language, Theology, Wildlife Biology, Wildlife Resources, Women’s Studies.

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• Resources related to data-mining and gaming on social networks

  - by darren

  Hi all I'm interested in the problem of patterning mining among players of social networking games. For example detecting cheaters of a game, given a company's user database. So far I have been following the usual recipe for a data mining project: construct a data warehouse that aggregates significant information select a classifier, and train it with a subsectio of records from the warehouse validate classifier with another test set lather, rinse, repeat Surprisingly, I've found very little in this area regarding literature, best practices, etc. I am hoping to crowdsource the information gathering problem here. Specifically what I'm looking for: What classifiers have worked will for this type of pattern mining (it seems highly temporal, users playing games, users receiving rewards, users transferring prizes etc). Are there any highly agreed upon attributes specific to social networking / gaming data? What is a practical amount of information that should be considered? One problem I've run into is data overload, where queries and data cleansing may take days to complete. Related to point above, what hardware resources are required to produce results? I've found it difficult to estimate the amount of computing power I will require for production use. It has become apparent that a white box in the corner does not have enough horse-power for such a project. Are companies generally resorting to cloud solutions? Are they buying clusters? Basically, any resources (theoretical, academic, or practical) about implementing a social networking / gaming pattern-mining program would be very much appreciated. Thanks.

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• C# File IO with Streams - Best Memory Buffer Size

  - by AJ

  Hi, I am writing a small IO library to assist with a larger (hobby) project. A part of this library performs various functions on a file, which is read / written via the FileStream object. On each StreamReader.Read(...) pass, I fire off an event which will be used in the main app to display progress information. The processing that goes on in the loop is vaired, but is not too time consuming (it could just be a simple file copy, for example, or may involve encryption...). My main question is: What is the best memory buffer size to use? Thinking about physical disk layouts, I could pick 2k, which would cover a CD sector size and is a nice multiple of a 512 byte hard disk sector. Higher up the abstraction tree, you could go for a larger buffer which could read an entire FAT cluster at a time. I realise with today's PC's, I could go for a more memory hungry option (a couple of MiB, for example), but then I increase the time between UI updates and the user perceives a less responsive app. As an aside, I'm eventually hoping to provide a similar interface to files hosted on FTP / HTTP servers (over a local network / fastish DSL). What would be the best memory buffer size for those (again, a "best-case" tradeoff between perceived responsiveness vs. performance). Thanks in advance for any ideas, Adam

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• Computed width with decimal values in Firefox, but without decimals in Webkit

  - by jävi

  Hello one more time! I have a strange problem working with HTML,CSS in different browsers: Firefox 3.6 and Webkit browsers (Chrome & Safari). My HTML looks like this: <div class="ln-letters"> <a href="#" class="all">ALL</a> <a href="#" class="a">A</a> <a href="#" class="b">B</a> <a href="#" class="c">C</a> </div> And my CSS is... .ln-letters a { font-family: 'Lucida Grande'; font-size:14px; display:block; float:left; padding:0px 7px; border-left:1px solid silver; border-right:none; text-decoration:none; } So as you can guess, each anchor gets a different width depending on its inner text. For example the first element with the text 'ALL' will be bigger (more width) than the others. Now the problem is that in Firefox (using Firebug) I can see that the computed width for the first element is 26.5667px, while in Chrome (using Chrome's developer tools) the computed width for the same element is exactly 27px. Therefore the div.ln-letters ends with different widths in each browser and that is causing me some troubles. Question is: there is any workaround to avoid Firefox computing decimal values? Or the opposite: to force Chrome to compute decimal values? Thank you in advance!

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• Web service SSL handshake fails in production environment unless SSL debugging enabled

  - by JST

  Scenario: calling a client web service over SSL (https) with mutual SSL authentication. Different service endpoint URLs and certs (both keystore and truststore) for test vs. production environments. Both test and production environments run tomcat / JBoss clustered. Production environment has load balancing / BigIP, runs Blade and non-Blade machines. Truststore is set (using -Djavax.net.ssl.trustStore=value) at startup. Keystore is set using System.setProperty("javax.net.ssl.keyStore", "value") in Java code. Web service call made using Axis2. All works fine in test environment, but when we moved to production environment (6 servers), it appears certs are not being forwarded for the handshake. Here's what we've done: in test environment, handshake using test versions of certs has been working all along, with no ssl debugging enabled confirmed in test environment that handshake with client production endpoint succeeds (production certs, both ours and theirs, are fine) -- this was done using -Djavax.net.debug=handshake,ssl confirmed that the error condition occurs on all 6 production servers took one server out of the cluster, turned on ssl debugging for just that one (with a restart), hit it directly, handshake works! switched to a different server without the debugging turned on, handshake error condition occurs turned debugging on on that second server (with a restart), hit it directly, handshake works! From the evidence, it seems like somehow the debugging being enabled causes the certificates to be properly retrieved/conveyed, although that makes no sense! I wonder whether somehow the enabled debugging makes the system pay attention to the System.setProperty call, and ignore it otherwise. However, in local and test environments, handshake worked without debugging enabled. Do I maybe need to be setting keystore on server startup like I'm setting truststore? Have been avoiding that because the keystore will differ for each of our test environments (16 of them).

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• Silverlight combobox performance issue

  - by Vinzz

  Hi, I'm facing a performance issue with a crowded combobox (5000 items). Rendering of the drop down list is really slow (as if it was computing all items before showing any). Do you have any trick to make this dropdown display lazy? Xaml code: <Grid x:Name="LayoutRoot"> <StackPanel Orientation="Horizontal" Width="200" Height="20"> <TextBlock>Test Combo </TextBlock> <ComboBox x:Name="fooCombo" Margin="5,0,0,0"></ComboBox> </StackPanel> </Grid> code behind: public MainPage() { InitializeComponent(); List<string> li = new List<string>(); int Max = 5000; for (int i = 0; i < Max; ++i) li.Add("Item - " + i); fooCombo.ItemsSource = li; }

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• Is there an "embedded DBMS" to support multiple writer applications (processes) on the same db files

  - by Amir Moghimi

  I need to know if there is any embedded DBMS (preferably in Java and not necessarily relational) which supports multiple writer applications (processes) on the same set of db files. BerkeleyDB supports multiple readers but just one writer. I need multiple writers and multiple readers. UPDATE: It is not a multiple connection issue. I mean I do not need multiple connections to a running DBMS application (process) to write data. I need multiple DBMS applications (processes) to commit on the same storage files. HSQLDB, H2, JavaDB (Derby) and MongoDB do not support this feature. I think that there may be some File System limitations that prohibit this. If so, is there a File System that allows multiple writers on a single file? Use Case: The use case is a high-throughput clustered system that intends to store its high-volume business log entries into a SAN storage. Storing business logs in separate files for each server does not fit because query and indexing capabilities are needed on the whole biz logs. Because "a SAN typically is its own network of storage devices that are generally not accessible through the regular network by regular devices", I want to use SAN network bandwidth for logging while cluster LAN bandwidth is being used for other server to server and client to server communications.

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• Displaying shifts on a timetable/calendar using C#

  - by Dave Peters

  I am very much a beginner and have experience of SQL and a tiny amount of VBA. What I am looking to do is create a tool to pull shift times from a database and to display them on a timetable/calendar. It will be part of a desktop application that the (very tech illiterate) end users will use to view and amend shift patterns. In essence it will be a grid with days on one axis and people on the other (I would however like to have the blocks proportional to shift length). In my mind it would potentially be a simple Gantt chart. All computing stuff I’ve learnt has been through trial and error and I want to use this project to get a much better understanding of C# as well as to get to the end product. I have been reading around for ways to tackle the problem and my issue is creating the timetable framework to which I will bind the data. I am using Visual Studio 2010 and SQL Server 2008 R2. Do you know of good resources which will either start me on the road to designing my own interface or give a basic framework I can adapt? All the resources I’ve found so far have been in different languages or for web based applications. Thank you for your time.

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• Required Working Precision for the BBP Algorithm?

  - by brainfsck

  Hello, I'm looking to compute the nth digit of Pi in a low-memory environment. As I don't have decimals available to me, this integer-only BBP algorithm in Python has been a great starting point. I only need to calculate one digit of Pi at a time. How can I determine the lowest I can set D, the "number of digits of working precision"? D=4 gives me many correct digits, but a few digits will be off by one. For example, computing digit 393 with precision of 4 gives me 0xafda, from which I extract the digit 0xa. However, the correct digit is 0xb. No matter how high I set D, it seems that testing a sufficient number of digits finds an one where the formula returns an incorrect value. I've tried upping the precision when the digit is "close" to another, e.g. 0x3fff or 0x1000, but cannot find any good definition of "close"; for instance, calculating at digit 9798 gives me 0xcde6 , which is not very close to 0xd000, but the correct digit is 0xd. Can anyone help me figure out how much working precision is needed to calculate a given digit using this algorithm? Thank you,

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• Function approximation with Maclaurin series

  - by marines

  I need to approx (1-x)^0.25 with given accuracy (0.0001 e.g.). I'm using expansion found on Wikipedia for (1+x)^0.25. I need to stop approximating when current expression is less than the accuracy. long double s(long double x, long double d) { long double w = 1; long double n = 1; // nth expression in series long double tmp = 1; // sum while last expression is greater than accuracy while (fabsl(tmp) >= d) { tmp *= (1.25 / n - 1) * (-x); // the next expression w += tmp; // is added to approximation n++; } return w; } Don't mind long double n. :P This works well when I'm not checking value of current expression but when I'm computing 1000 or more expressions. Domain of the function is <-1;1 and s() calculates approximation well for x in <-1;~0.6. The bigger the argument is the bigger is the error of calculation. From 0.6 it exceeds the accuracy. I'm not sure if the problem is clear enough because I don't know English math language well. The thing is what's the matter with while condition and why the function s() doesn't approximate correctly.

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• OleDbExeption Was unhandled in VB.Net

  - by ritch

  Syntax error (missing operator) in query expression '((ProductID = ?) AND ((? = 1 AND Product Name IS NULL) OR (Product Name = ?)) AND ((? = 1 AND Price IS NULL) OR (Price = ?)) AND ((? = 1 AND Quantity IS NULL) OR (Quantity = ?)))'. I need some help sorting this error out in Visual Basics.Net 2008. I am trying to update records in a MS Access Database 2008. I have it being able to update one table but the other table is just not having it. Private Sub Admin_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 'Reads Users into the program from the text file (Located at Module.VB) ReadUsers() 'Connect To Access 2007 Database File con.ConnectionString = ("Provider=Microsoft.ACE.OLEDB.12.0;" & "Data Source=E:\Computing\Projects\Login\Login\bds.accdb;") con.Open() 'SQL connect 1 sql = "Select * From Clients" da = New OleDb.OleDbDataAdapter(sql, con) da.Fill(ds, "Clients") MaxRows = ds.Tables("Clients").Rows.Count intCounter = -1 'SQL connect 2 sql2 = "Select * From Products" da2 = New OleDb.OleDbDataAdapter(sql2, con) da2.Fill(ds, "Products") MaxRows2 = ds.Tables("Products").Rows.Count intCounter2 = -1 'Show Clients From Database in a ComboBox ComboBoxClients.DisplayMember = "ClientName" ComboBoxClients.ValueMember = "ClientID" ComboBoxClients.DataSource = ds.Tables("Clients") End Sub The button, the error appears on da2.update(ds, "Products") Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click Dim cb2 As New OleDb.OleDbCommandBuilder(da2) ds.Tables("Products").Rows(intCounter2).Item("Price") = ProductPriceBox.Text da2.Update(ds, "Products") 'Alerts the user that the Database has been updated MsgBox("Database Updated") End Sub However the code works on updating another table Private Sub UpdateButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles UpdateButton.Click 'Allows users to update records in the Database Dim cb As New OleDb.OleDbCommandBuilder(da) 'Changes the database contents with the content in the text fields ds.Tables("Clients").Rows(intCounter).Item("ClientName") = ClientNameBox.Text ds.Tables("Clients").Rows(intCounter).Item("ClientID") = ClientIDBox.Text ds.Tables("Clients").Rows(intCounter).Item("ClientAddress") = ClientAddressBox.Text ds.Tables("Clients").Rows(intCounter).Item("ClientTelephoneNumber") = ClientNumberBox.Text 'Updates the table withing the Database da.Update(ds, "Clients") 'Alerts the user that the Database has been updated MsgBox("Database Updated") End Sub

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• Pros & Cons of Google App Engine

  - by Rishi

  Pros & Cons of Google App Engine [An Updated List 21st Aug 09] Help me Compile a List of all the Advantages & Disadvantages of Building an Application on the Google App Engine Pros: 1) No Need to buy Servers or Server Space (no maintenance). 2) Makes solving the problem of scaling much easier. Cons: 1) Locked into Google App Engine ?? 2)Developers have read-only access to the filesystem on App Engine. 3)App Engine can only execute code called from an HTTP request (except for scheduled background tasks). 4)Users may upload arbitrary Python modules, but only if they are pure-Python; C and Pyrex modules are not supported. 5)App Engine limits the maximum rows returned from an entity get to 1000 rows per Datastore call. 6)Java applications may only use a subset (The JRE Class White List) of the classes from the JRE standard edition. 7)Java applications cannot create new threads. Known Issues!! http://code.google.com/p/googleappengine/issues/list Hard limits Apps per developer - 10 Time per request - 30 sec Files per app - 3,000 HTTP response size - 10 MB Datastore item size - 1 MB Application code size - 150 MB Pro or Con? App Engine's infrastructure removes many of the system administration and development challenges of building applications to scale to millions of hits. Google handles deploying code to a cluster, monitoring, failover, and launching application instances as necessary. While other services let users install and configure nearly any *NIX compatible software, App Engine requires developers to use Python or Java as the programming language and a limited set of APIs. Current APIs allow storing and retrieving data from a BigTable non-relational database; making HTTP requests; sending e-mail; manipulating images; and caching. Most existing Web applications can't run on App Engine without modification, because they require a relational database.

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• Weblogic 10.3.0 : Loosing a stateless session bean in the bean pool

  - by KlasE

  Hi, We have a strange situation where we loose a Stateless SessionBean in a Bean Pool in Weblogic 10.3.0 Since we only have one bean in the pool, this effectively hangs all incoming calls. We do not want more than one instance in the pool because of application restrictions. In the Weblogic admin console, we can see that there are 1 instance in the bean pool, 0 beans in use and 1 waiting incoming request. The question is, what can have caused the system to not send the request to the one obviously free bean instance? This happens after several hours and over 100000 incoming requests, and the same scenario worked fine in the old weblogic 8 environment. We get the following stacktrace: "[ACTIVE] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'" waiting for lock java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject@b0d484 TIMED_WAITING sun.misc.Unsafe.park(Native Method) java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:198) java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2054) weblogic.ejb.container.pool.StatelessSessionPool.waitForBean(StatelessSessionPool.java:269) weblogic.ejb.container.pool.StatelessSessionPool.getBean(StatelessSessionPool.java:111) weblogic.ejb.container.manager.StatelessManager.preInvoke(StatelessManager.java:148) weblogic.ejb.container.internal.BaseRemoteObject.preInvoke(BaseRemoteObject.java:227) weblogic.ejb.container.internal.StatelessRemoteObject.preInvoke(StatelessRemoteObject.java:52) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl.isMyStuffValid(MessageLogFacace_n73y0z_EOImpl.java:261) com.mycompany.beans.MessageLogFacace_n73y0z_EOImpl_WLSkel.invoke(Unknown Source) weblogic.rmi.internal.BasicServerRef.invoke(BasicServerRef.java:589) weblogic.rmi.cluster.ClusterableServerRef.invoke(ClusterableServerRef.java:230) weblogic.rmi.internal.BasicServerRef$1.run(BasicServerRef.java:477) weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:363) weblogic.security.service.SecurityManager.runAs(Unknown Source) weblogic.rmi.internal.BasicServerRef.handleRequest(BasicServerRef.java:473) weblogic.rmi.internal.wls.WLSExecuteRequest.run(WLSExecuteRequest.java:118) weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) weblogic.work.ExecuteThread.run(ExecuteThread.java:173) Any help would be very welcome. Regards Klas

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• how to better (inambiguaously) use the terms CAPTCHA and various types of interactions?

  - by vgv8

  I am working on survey of state-of-the-art and trends of spam prevention techniques. I observe that non-intrusive, transparent to visitor spam prevention techniques (like context-based filtering or honey traps) are frequently called non-captcha. Is it correct understanding of term CAPTCHA which is "type of challenge-response [ 2 ]test used in computing to ensure that the response is not generated by a compute" [ 1 ] and challenge-response does not seem to imply obligatory human involvement. So, which understanding (definition) of term and classification I'd better to stick with? How would I better call CAPTCHA without direct human interaction in order to avoid ambiguity and confusion of terms understnding? How would I better (succinctly and unambiguously) coin the term for captchas requiring human interaction but without typing into textbox? How would I better (succinctly and unambiguously) coin the terms to mark the difference between human interaction with images (playing, drag&dropping, rearranging, clicking with images) vs. just recognizing them (and then typing into a textbox the answer without interaction with images)? PS. The problem is that recognition of a wiggled word in an image or typing the answer to question is also interaction and when I start to use the terms "interaction", "interactive", "captcha", "protection", "non-captcha", "non-interactive", "static", "dynamic", "visible", "hidden" the terms overlap ambiguously with which another (especailly because the definitions or their actual practice of usage are vague or contradictive). [ 1 ] http://en.wikipedia.org/wiki/CAPTCHA

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• script to find "deny" ACE in ACLs, and remove it

  - by Tom

  On my 100TB cluster, I need to find dirs and files that have a "deny" ACE within their ACL, then remove that ACE on each instance. I'm using the following: # find . -print0 | xargs -0 ls -led | grep deny -B4 and get this output (partial, for example only) -r--rw---- 1 chris GroupOne 4096 Mar 6 18:12 ./directoryA/fileX.txt OWNER: user:chris GROUP: group:GroupOne 0: user:chris allow file_gen_read,std_write_dac,file_write_attr 1: user:chris deny file_write,append,file_write_ext_attr,execute -- -r--rwxrwx 1 chris GroupOne 14728221 Mar 6 18:12 ./directoryA/subdirA/fileZ.txt OWNER: user:chris GROUP: group:GroupOne 0: user:chris allow file_gen_read,std_write_dac,file_write_attr 1: user:chris deny file_write,append,file_write_ext_attr,execute -- OWNER: user:bob GROUP: group:GroupTwo 0: user:bob allow dir_gen_read,dir_gen_write,dir_gen_execute,std_write_dac,delete_child,object_inherit,container_inherit 1: group:GroupTwo allow std_read_dac,std_write_dac,std_synchronize,dir_read_attr,dir_write_attr,object_inherit,container_inherit 2: group:GroupTwo deny list,add_file,add_subdir,dir_read_ext_attr,dir_write_ext_attr,traverse,delete_child,object_inherit,container_inherit -- As you can see, depending on where the "deny" ACE is, I can see/not-see the path. I could increase the -B value (I've seen up to 8 ACEs on a file) but then I would get more output to distill from... What I need to do next is extract $ACENUMBER and $PATHTOFILE so that I can execute this command: chmod -a# $ACENUMBER $PATHTOFILE Additional issue is that the find command (above) gives a relative path, whereas I need the full path. I guess that would need to be edited somehow. Any guidance on how to accomplish this?

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• Linux 2.6.31 Scheduler and Multithreaded Jobs

  - by dsimcha

  I run massively parallel scientific computing jobs on a shared Linux computer with 24 cores. Most of the time my jobs are capable of scaling to 24 cores when nothing else is running on this computer. However, it seems like when even one single-threaded job that isn't mine is running, my 24-thread jobs (which I set for high nice values) only manage to get ~1800% CPU (using Linux notation). Meanwhile, about 500% of the CPU cycles (again, using Linux notation) are idle. Can anyone explain this behavior and what I can do about it to get all of the 23 cores that aren't being used by someone else? Notes: In case it's relevant, I have observed this on slightly different kernel versions, though I can't remember which off the top of my head. The CPU architecture is x64. Is it at all possible that the fact that my 24-core jobs are 32-bit and the other jobs I'm competing w/ are 64-bit is relevant? Edit: One thing I just noticed is that going up to 30 threads seems to alleviate the problem to some degree. It gets me up to ~2100% CPU.

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• Maintain order of messages via proxies to app servers

  - by David Turner

  Hi, I am receiving messages from a 3rd party via a http post, and it is important that the order the messages hit our infrastructure is maintained through the load balancers and proxies until it hits our application server. Quick Diagram. (proxies in place due to security requirements.) [ACE load balancer] - [2 proxies] - [Application Servers] or maybe [ACE load balancer] - [2 proxies] - [ACE load balancer] - [Application Servers] My idea was that I would setup the load balancers in active-passive mode, to force all messages to use one proxy, and then both the proxies would hit a second load balancer that would be configured in active passive to hit one application server. Whilst the above is not ideal, it does give me resilience, and once the message is in my app servers, I enter a stateless world, and load balance across both nodes of my cluster. However, I am concerned that even a single proxy could send messages out of order, perhaps if 2 messages are recived very close together, message 2 might get processed faster than message 1. Is this possible? Likely? Is there a simple open source proxy (MOD_PROXY?) that can be easily configured to just pass messages through it, and to guarantee to send the messages through in the order they are received. If so which, and finally links to how I should configure it would be great. In fact any links to articles around avoiding "out of order" messages using hardware would be gratefully received. Thanks, ps for those that are interested, the app is a java spring integration application currently on a appliation server.

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• shell scripting: search/replace & check file exist

  - by johndashen

  I have a perl script (or any executable) E which will take a file foo.xml and write a file foo.txt. I use a Beowulf cluster to run E for a large number of XML files, but I'd like to write a simple job server script in shell (bash) which doesn't overwrite existing txt files. I'm currently doing something like #!/bin/sh PATTERN="[A-Z]*0[1-2][a-j]"; # this matches foo in all cases todo=`ls *.xml | grep $PATTERN -o`; isdone=`ls *.txt | grep $PATTERN -o`; whatsleft=todo - isdone; # what's the unix magic? #tack on the .xml prefix with sed or something #and then call the job server; jobserve E "$whatsleft"; and then I don't know how to get the difference between $todo and $isdone. I'd prefer using sort/uniq to something like a for loop with grep inside, but I'm not sure how to do it (pipes? temporary files?) As a bonus question, is there a way to do lookahead search in bash grep? To clarify: so the simplest way to do what i'm asking is (in pseudocode) for i in `/bin/ls *.xml` do replace xml suffix with txt if [that file exists] add to whatsleft list end done

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• Where to find algorithms for standard math functions?

  - by dsimcha

  I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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• Detecting death of spawned process using Window CRT

  - by Michael Tiller

  Executive summary: I need a way to determine whether a Windows process I've spawned via _spawnl and am communicating with using FDs from _pipe has died. Details: I'm using the low-level CRT function in Windows (_eof, _read) to communicate with a process that was spawned via a call to _spawnl (with the P_NOWAIT) flag. I'm using _pipe to create file descriptors to communicate with this spawned process and passing those descriptors (the FD #) to it on the command line. It is worth mentioning that I don't control the spawned process. It's a black box to me. It turns out that the process we are spawning occasionally crashes. I'm trying to make my code robust to this by detecting the crash. Unfortunately, I can't see a way to do this. It seems reasonable to me to expect that a call to _eof or _read on one of those descriptors would return an error status (-1) if the process had died. Unfortunately, that isn't the case. It appears that the descriptors have a life of their own independent of the spawned process. So even though the process on the other end is dead, I get no error status on the file descriptor I'm using to communicate with it. I've got the PID for the nested process (returned from the _spanwnl call) but I don't see anything I can do with that. My code works really well except for one thing. I can't detect whether the spawned process is simply busy computing me an answer or has died. If I can use the information from _pipe and _spawnl to determine if the spawned process is dead, I'll be golden. Suggestions very welcome. Thanks in advance. UPDATE: I found a fairly simple solution and added it as the selected answer.

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• Testing a wide variety of computers with a small company

  - by Tom the Junglist

  Hello everyone, I work for a small dotcom which will soon be launching a reasonably-complicated Windows program. We have uncovered a number of "WTF?" type scenarios that have turned up as the program has been passed around to the various not-technical-types that we've been unable to replicate. One of the biggest problems we're facing is that of testing: there are a total of three programmers -- only one working on this particular project, me -- no testers, and a handful of assorted other staff (sales, etc). We are also geographically isolated. The "testing lab" consists of a handful of VMWare and VPC images running sort-of fresh installs of Windows XP and Vista, which runs on my personal computer. The non-technical types try to be helpful when problems arise, we have trained them on how to most effectively report problems, and the software itself sports a wide array of diagnostic features, but since they aren't computer nerds like us their reporting is only so useful, and arranging remote control sessions to dig into the guts of their computers is time-consuming. I am looking for resources that allow us to amplify our testing abilities without having to put together an actual lab and hire beta testers. My boss mentioned rental VPS services and asked me to look in to them, however they are still largely very much self-service and I was wondering if there were any better ways. How have you, or any other companies in a similar situation handled this sort of thing? EDIT: According to the lingo, our goal here is to expand our systems testing capacity via an elastic computing platform such as Amazon EC2. At this point I am not sure suggestions of beefing up our unit/integration testing are going to help very much as we are consistently hitting walls at the systems testing phase. Has anyone attempted to do this kind of software testing on a cloud-type service like EC2? Tom

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• Problem with JMX query of Coherence node MBeans visible in JConsole

  - by Quinn Taylor

  I'm using JMX to build a custom tool for monitoring remote Coherence clusters at work. I'm able to connect just fine and query MBeans directly, and I've acquired nearly all the information I need. However, I've run into a snag when trying to query MBeans for specific caches within a cluster, which is where I can find stats about total number of gets/puts, average time for each, etc. The MBeans I'm trying to access programatically are visible when I connect to the remote process using JConsole, and have names like this: Coherence:type=Cache,service=SequenceQueue,name=SEQ%GENERATOR,nodeId=1,tier=back It would make it more flexible if I can dynamically grab all type=Cache MBeans for a particular node ID without specifying all the caches. I'm trying to query them like this: QueryExp specifiedNodeId = Query.eq(Query.attr("nodeId"), Query.value(nodeId)); QueryExp typeIsCache = Query.eq(Query.attr("type"), Query.value("Cache")); QueryExp cacheNodes = Query.and(specifiedNodeId, typeIsCache); ObjectName coherence = new ObjectName("Coherence:*"); Set<ObjectName> cacheMBeans = mBeanServer.queryMBeans(coherence, cacheNodes); However, regardless of whether I use queryMBeans() or queryNames(), the query returns a Set containing... ...0 objects if I pass the arguments shown above ...0 objects if I pass null for the first argument ...all MBeans in the Coherence:* domain (112) if I pass null for the second argument ...every single MBean (128) if I pass null for both arguments The first two results are the unexpected ones, and suggest a problem in the QueryExp I'm passing, but I can't figure out what the problem is. I even tried just passing typeIsCache or specifiedNodeId for the second parameter (with either coherence or null as the first parameter) and I always get 0 results. I'm pretty green with JMX — any insight on what the problem is? (FYI, the monitoring tool will be run on Java 5, so things like JMX 2.0 won't help me at this point.)

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• I'v installed NetBeans 6.8 on my MacOS X MacBook and the logs say it cannot be run, any ideas?

  - by codezealot

  I've installed NetBeans 6.8 on my MacBook, and the installation results indicated success. However, every single time I attempt to run the application is shuts down. I monitored the process and noticed the following entries in the console that imply the application cannot be found? 3/19/10 10:20:20 PM [0x0-0x22022].org.netbeans.ide.baseide.200912041610[22168] /Applications/NetBeans/NetBeans 6.8.app/Contents/MacOS/netbeans: line 57: dirname: command not found 3/19/10 10:20:20 PM [0x0-0x22022].org.netbeans.ide.baseide.200912041610[22168] Cannot read cluster file: /../etc/netbeans.clusters 3/19/10 10:20:20 PM com.apple.launchd.peruser.501[77] ([0x0-0x22022].org.netbeans.ide.baseide.200912041610[22168]) Exited with exit code: 1 I started researching how to set the default JDK for use by NetBeans, and found repeated use of the following command line entry; netbeans --jdkhome /System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home -- from http://wiki.netbeans.org/JDKVersionAndMacOS When I attempt the command line above, I receive "netbeans command not found". So do I ... 1.) Need to create a command called "netbeans" that points to my install location for NetBeans 6.8? If so how do I do that? 2.) How do I get to the netbeans.conf file for NetBeans 6.8, does one even exist for it? It gets even more interesting, the above happens with Eclipse as well. Yippie.

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• How to perform spatial partitioning in n-dimensions?

  - by kevin42

  I'm trying to design an implementation of Vector Quantization as a c++ template class that can handle different types and dimensions of vectors (e.g. 16 dimension vectors of bytes, or 4d vectors of doubles, etc). I've been reading up on the algorithms, and I understand most of it: here and here I want to implement the Linde-Buzo-Gray (LBG) Algorithm, but I'm having difficulty figuring out the general algorithm for partitioning the clusters. I think I need to define a plane (hyperplane?) that splits the vectors in a cluster so there is an equal number on each side of the plane. [edit to add more info] This is an iterative process, but I think I start by finding the centroid of all the vectors, then use that centroid to define the splitting plane, get the centroid of each of the sides of the plane, continuing until I have the number of clusters needed for the VQ algorithm (iterating to optimize for less distortion along the way). The animation in the first link above shows it nicely. My questions are: What is an algorithm to find the plane once I have the centroid? How can I test a vector to see if it is on either side of that plane?

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• randomized quicksort: probability of two elements comparison?

  - by bantu

  I am reading "Probability and Computing" by M.Mitzenmacher, E.Upfal and I have problems understanding how the probability of comparison of two elements is calculated. Input: the list (y1,y2,...,YN) of numbers. We are looking for pivot element. Question: what is probability that two elements yi and yj (ji) will be compared? Answer (from book): yi and yj will be compared if either yi or yj will be selected as pivot in first draw from sequence (yi,yi+1,...,yj-1,yj). So the probablity is: 2/(y-i+1). The problem for me is initial claim: for example, picking up yi in the first draw from the whole list will cause the comparison with yj (and vice-versa) and the probability is 2/n. So, rather the "reverse" claim is true -- none of the (yi+1,...,yj-1) elements can be selected beforeyi or yj, but the "pool" size is not fixed (in first draw it is n for sure, but on the second it is smaller). Could someone please explain this, how the authors come up with such simplified conclusion? Thank you in advance

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