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  • approximating log10[x^k0 + k1]

    - by Yale Zhang
    Greetings. I'm trying to approximate the function Log10[x^k0 + k1], where .21 < k0 < 21, 0 < k1 < ~2000, and x is integer < 2^14. k0 & k1 are constant. For practical purposes, you can assume k0 = 2.12, k1 = 2660. The desired accuracy is 5*10^-4 relative error. This function is virtually identical to Log[x], except near 0, where it differs a lot. I already have came up with a SIMD implementation that is ~1.15x faster than a simple lookup table, but would like to improve it if possible, which I think is very hard due to lack of efficient instructions. My SIMD implementation uses 16bit fixed point arithmetic to evaluate a 3rd degree polynomial (I use least squares fit). The polynomial uses different coefficients for different input ranges. There are 8 ranges, and range i spans (64)2^i to (64)2^(i + 1). The rational behind this is the derivatives of Log[x] drop rapidly with x, meaning a polynomial will fit it more accurately since polynomials are an exact fit for functions that have a derivative of 0 beyond a certain order. SIMD table lookups are done very efficiently with a single _mm_shuffle_epi8(). I use SSE's float to int conversion to get the exponent and significand used for the fixed point approximation. I also software pipelined the loop to get ~1.25x speedup, so further code optimizations are probably unlikely. What I'm asking is if there's a more efficient approximation at a higher level? For example: Can this function be decomposed into functions with a limited domain like log2((2^x) * significand) = x + log2(significand) hence eliminating the need to deal with different ranges (table lookups). The main problem I think is adding the k1 term kills all those nice log properties that we know and love, making it not possible. Or is it? Iterative method? don't think so because the Newton method for log[x] is already a complicated expression Exploiting locality of neighboring pixels? - if the range of the 8 inputs fall in the same approximation range, then I can look up a single coefficient, instead of looking up separate coefficients for each element. Thus, I can use this as a fast common case, and use a slower, general code path when it isn't. But for my data, the range needs to be ~2000 before this property hold 70% of the time, which doesn't seem to make this method competitive. Please, give me some opinion, especially if you're an applied mathematician, even if you say it can't be done. Thanks.

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  • Custom DataGridView column sort based on Value not Formatted value

    - by Dan Neely
    I have a custom DGV cell I'm using to display the contents of MyType objects. To control how they're being formatted I'm overriding the GetFormattedValue() and FormattedvalueType methods of DataGridViewTextBoxCell because in this case I don't want to use the default ToString() method. The problem is that when I do this the DGV is sorting the column by the string in FormattedValue instead of by Value. I'm not seeing a method I can override to change the sort behavior of the column. While I know I can, I don't want to have to write custom Sort mthods for the DGVs themselves because I'm using this in multiple DGV's.

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  • Why don't Domain class static methods work from inside a grails "service"?

    - by ?????
    I want a grails service to be able to access Domain static methods, for queries, etc. For example, in a controller, I can call IncomingCall.count() to get the number of records in table "IncomingCall" but if I try to do this from inside a service, I get the error: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'incomingStatusService': Invocation of init method failed; nested exception is groovy.lang.MissingMethodException: No signature of method: static ms.wdw.tropocontrol.IncomingCall.count() is applicable for argument types: () values: [] How do these methods get injected? There's no magic def statement in a controller that appears to do this. Or is the problem that Hibernate isn't available from my Service class?

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  • What's the best way to unit test code that generates random output?

    - by Flynn1179
    Specifically, I've got a method picks n items from a list in such a way that a% of them meet one criterion, and b% meet a second, and so on. A simplified example would be to pick 5 items where 50% have a given property with the value 'true', and 50% 'false'; 50% of the time the method would return 2 true/3 false, and the other 50%, 3 true/2 false. Statistically speaking, this means that over 100 runs, I should get about 250 true/250 false, but because of the randomness, 240/260 is entirely possible. What's the best way to unit test this? I'm assuming that even though technically 300/200 is possible, it should probably fail the test if this happens. Is there a generally accepted tolerance for cases like this, and if so, how do you determine what that is?

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  • Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I'm not seeing what I expect when I use ABCMeta and abstractmethod. This works fine in python3: from abc import ABCMeta, abstractmethod class Super(metaclass=ABCMeta): @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... And in 2.6: class Super(): __metaclass__ = ABCMeta @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... They both also work fine (I get the expected exception) if I derive Super from object, in addition to ABCMeta. They both "fail" (no exception raised) if I derive Super from list. I want an abstract base class to be a list but abstract, and concrete in sub classes. Am I doing it wrong, or should I not want this in python?

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  • What is the difference between the add and offer methods in a queue?

    - by Finbarr
    Take the PriorityQueue for example http://java.sun.com/j2se/1.5.0/docs/api/java/util/PriorityQueue.html#offer(E) According to the Collection API entry http://java.sun.com/j2se/1.5.0/docs/api/java/util/Collection.html the add method will often seek to ensure that an element exists within the Collection rather than adding duplicates. So my question is, what is the difference between the add and offer methods? Is it that the Offer method will add duplicates regardless? (I doubt that it is because if a Collection should only have distinct elements this would circumvent that).

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  • Is there any way to load all UI controls before displaying? C# winform

    - by Nabil
    I have a complicate win form with lots of controls and bulky repaints, controls resizeing and positioning according to user screen, this causes the form to be shown while doing some rendering and repainting. Is there any way to load UI and prepare it before displaying??I mean showing final UI after the whole repainting events done. If using splash screen, before loading the main form, how should I do that?? Thanks

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  • Starting Frame-By-Frame Animation

    - by OceanBlue
    Hi, I have a basic question about starting a frame-by-frame animation. When I call the AnimationDrawable.start() method from my code directly, it doesn't seem to work. public void onCreate(Bundle savedInstanceState) { ... mAnimation.start(); ... } But if I put this line inside the onClick() callback method of a button, pressing the buton starts the animation. Why doesn't this line work in the code? Thanks!

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  • Path Problem in ASP.net

    - by Hany
    Hi I am trying to do the following I am building asp.net website with c# language I want to read a text file from my project(the file is inside the project) I tried to get the file Path by this way : string path=Request.PhysicalApplicationPath+"filename.txt"; but I can't use The "Request" object from separated C# file ?? note: separated C3 file,I mean it's not related with aspx file can you help me with my way or do you have another way ?? thx

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  • What to name 2 methods with same signatures

    - by coffeeaddict
    Initially I had a method in our DL that would take in the object it's updating like so: internal void UpdateCash(Cash Cash) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set captureID = @captureID, ac_code = @acCode, captureDate = @captureDate, errmsg = @errorMessage, isDebit = @isDebit, SourceInfoID = @sourceInfoID, PayPalTransactionInfoID = @payPalTransactionInfoID, CreditCardTransactionInfoID = @CreditCardTransactionInfoID where id = @cashID"; conn.AddParam("@captureID", cash.CaptureID); conn.AddParam("@acCode", cash.ActionCode); conn.AddParam("@captureDate", cash.CaptureDate); conn.AddParam("@errorMessage", cash.ErrorMessage); conn.AddParam("@isDebit", cyberCash.IsDebit); conn.AddParam("@PayPalTransactionInfoID", cash.PayPalTransactionInfoID); conn.AddParam("@CreditCardTransactionInfoID", cash.CreditCardTransactionInfoID); conn.AddParam("@sourceInfoID", cash.SourceInfoID); conn.AddParam("@cashID", cash.Id); conn.ExecuteNonQuery(); } } My boss felt that creating an object every time just to update one or two fields is overkill. But I had a couple places in code using this. He recommended using just UpdateCash and sending in the ID for CAsh and field I want to update. Well the problem is I have 2 places in code using my original method. And those 2 places are updating 2 completely different fields in the Cash table. Before I was just able to get the existing Cash record and shove it into a Cash object, then update the properties I wanted to be updated in the DB, then send back the cash object to my method above. I need some advice on what to do here. I have 2 methods and they have the same signature. I'm not quite sure what to rename these because both are updating 2 completely different fields in the Cash table: internal void UpdateCash(int cashID, int paypalCaptureID) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set CaptureID = @paypalCaptureID where id = @cashID"; conn.AddParam("@captureID", paypalCaptureID); conn.ExecuteNonQuery(); } } internal void UpdateCash(int cashID, int PayPalTransactionInfoID) { using (OurCustomDbConnection conn = CreateConnection("UpdateCash")) { conn.CommandText = @"update Cash set PaymentSourceID = @PayPalTransactionInfoID where id = @cashID"; conn.AddParam("@PayPalTransactionInfoID", PayPalTransactionInfoID); conn.ExecuteNonQuery(); } } So I thought hmm, maybe change the names to these so that they are now unique and somewhat explain what field its updating: UpdateCashOrderID UpdateCashTransactionInfoID ok but that's not really very good names. And I can't go too generic, for example: UpdateCashTransaction(int cashID, paypalTransactionID) What if we have different types of transactionIDs that the cash record holds besides just the paypalTransactionInfoID? such as the creditCardInfoID? Then what? Transaction doesn't tell me what kind. And furthermore what if you're updating 2 fields so you have 2 params next to the cashID param: UpdateCashTransaction(int cashID, paypalTransactionID, someOtherFieldIWantToUpdate) see my frustration? what's the best way to handle this is my boss doesn't like my first route?

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  • Python - werid behavior

    - by orokusaki
    I've done what I shouldn't have done and written 4 modules (6 hours or so) without running any tests along the way. I have a method inside of /mydir/__init__.py called get_hash(), and a class inside of /mydir/utils.py called SpamClass. /mydir/utils.py imports get_hash() from /mydir/__init__. /mydir/__init__.py imports SpamClass from /mydir/utils.py. Both the class and the method work fine on their own but for some reason if I try to import /mydir/, I get an import error saying "Cannot import name get_hash" from /mydir/__init__.py. The only stack trace is the line saying that __init__.py imported SpamClass. The next line is where the error occurs in in SpamClass when trying to import get_hash. Why is this?

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  • Java Box Class: Unsolvable: aligning components to the left or right

    - by user323186
    I have been trying to left align buttons contained in a Box to the left, with no success. They align left alright, but for some reason dont shift all the way left as one would imagine. I attach the code below. Please try compiling it and see for yourself. Seems bizarre to me. Thanks, Eric import java.awt.Dimension; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.JButton; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JMenu; import javax.swing.JMenuBar; import javax.swing.JMenuItem; import javax.swing.JScrollPane; import javax.swing.JTextArea; public class MainGUI extends Box implements ActionListener{ //Create GUI Components Box centerGUI=new Box(BoxLayout.X_AXIS); Box bottomGUI=new Box(BoxLayout.X_AXIS); //centerGUI subcomponents JTextArea left=new JTextArea(), right=new JTextArea(); JScrollPane leftScrollPane = new JScrollPane(left), rightScrollPane = new JScrollPane(right); //bottomGUI subcomponents JButton encrypt=new JButton("Encrypt"), decrypt=new JButton("Decrypt"), close=new JButton("Close"), info=new JButton("Info"); //Create Menubar components JMenuBar menubar=new JMenuBar(); JMenu fileMenu=new JMenu("File"); JMenuItem open=new JMenuItem("Open"), save=new JMenuItem("Save"), exit=new JMenuItem("Exit"); int returnVal =0; public MainGUI(){ super(BoxLayout.Y_AXIS); initCenterGUI(); initBottomGUI(); initFileMenu(); add(centerGUI); add(bottomGUI); addActionListeners(); } private void addActionListeners() { open.addActionListener(this); save.addActionListener(this); exit.addActionListener(this); encrypt.addActionListener(this); decrypt.addActionListener(this); close.addActionListener(this); info.addActionListener(this); } private void initFileMenu() { fileMenu.add(open); fileMenu.add(save); fileMenu.add(exit); menubar.add(fileMenu); } public void initCenterGUI(){ centerGUI.add(leftScrollPane); centerGUI.add(rightScrollPane); } public void initBottomGUI(){ bottomGUI.setAlignmentX(LEFT_ALIGNMENT); //setBorder(BorderFactory.createLineBorder(Color.BLACK)); bottomGUI.add(encrypt); bottomGUI.add(decrypt); bottomGUI.add(close); bottomGUI.add(info); } @Override public void actionPerformed(ActionEvent arg0) { // find source of the action Object source=arg0.getSource(); //if action is of such a type do the corresponding action if(source==close){ kill(); } else if(source==open){ //CHOOSE FILE File file1 =chooseFile(); String input1=readToString(file1); System.out.println(input1); left.setText(input1); } else if(source==decrypt){ //decrypt everything in Right Panel and output in left panel decrypt(); } else if(source==encrypt){ //encrypt everything in left panel and output in right panel encrypt(); } else if(source==info){ //show contents of info file in right panel doInfo(); } else { System.out.println("Error"); //throw new UnimplementedActionException(); } } private void doInfo() { // TODO Auto-generated method stub } private void encrypt() { // TODO Auto-generated method stub } private void decrypt() { // TODO Auto-generated method stub } private String readToString(File file) { FileReader fr = null; try { fr = new FileReader(file); } catch (FileNotFoundException e1) { e1.printStackTrace(); } BufferedReader br=new BufferedReader(fr); String line = null; try { line = br.readLine(); } catch (IOException e) { e.printStackTrace(); } String input=""; while(line!=null){ input=input+"\n"+line; try { line=br.readLine(); } catch (IOException e) { e.printStackTrace(); } } return input; } private File chooseFile() { //Create a file chooser final JFileChooser fc = new JFileChooser(); returnVal = fc.showOpenDialog(fc); return fc.getSelectedFile(); } private void kill() { System.exit(0); } public static void main(String[] args) { // TODO Auto-generated method stub MainGUI test=new MainGUI(); JFrame f=new JFrame("Tester"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setJMenuBar(test.menubar); f.setPreferredSize(new Dimension(600,400)); //f.setUndecorated(true); f.add(test); f.pack(); f.setVisible(true); } }

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  • Saving auto increment in MySQL

    - by oshafran
    Hello, I am trying to sync between 2 tables: I have active table where has auto_increment, and I have archive table with the same values. I would like both ID's to be unique (between the tables as well) - I mean, I would like to save auto incremenet, and if I UNION both table I still have uniqness. How can I do that? Is there a possibility to save auto increment when mysql is off?

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  • SQL Server Merge statement issue

    - by George2
    Hello everyone, I am learning and using SQL Server 2008 new Merge statement, merge statement will compare/operate source table and destination table row by row ("operate" I mean operations performed for when matched or not-matched conditions). My question is whether the whole merge process will be one transaction or each row comparison/operation will be one transaction? Appreciate if any document to prove it. thanks in advance, George

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  • Where do all these messages come from?

    - by stacker
    This configuration works fine, but inbound-channel-adapter which is supposed to poll every 15 secs is running continously. Does anyone have an idea what I'm doning wrong? <si:channel id="msgChannel" /> <si:inbound-channel-adapter ref="jdbcInputAdapter" method="fetchData" channel="msgChannel"> <si:poller> <si:interval-trigger interval="15000" /> </si:poller> </si:inbound-channel-adapter> <si:outbound-channel-adapter ref="shouter" method="shout" channel="msgChannel"/>

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  • How can I debug or set a break statement inside an expression tree?

    - by Abel
    When an external library contains a LINQ provider, and it throws an exception when executing a dynamic expression tree, how can I break when that expression is thrown? For example, I use a third party LINQ2CRM provider, which allows me to call the Max<TSource, TResult>() method of IQueryable, but when it throws an InvalidCastException, I fail to break on the spot when the exception is thrown, making it hard to review the stack-trace because it's already unwinded when the debugger breaks it in my code. I've set "break on throw" for the mentioned exception. My debug settings are: Clarification on where exactly I'd want to break. I do not want to break in side the LINQ Expression, but instead, I want to break when the expression tree is executed, or, put in other words, when the IQueryable extension method Max() calls the override provided by the LINQ provider. The top of the stacktrace looks like this, which is where I would like to break inside (or step through, or whatever): at XrmLinq.QueryProviderBase.Execute[T](Expression expression) at System.Linq.Queryable.Max[TSource,TResult](IQueryable`1 source, Expression`1 selector)

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  • How to get a reference to IDuplexChannel, IDuplexSessionChannel or IOutputChannel in Wcf

    - by wizlb
    I have a duplex Wcf service and I'd like to get a reference to IDuplexChannel, IDuplexSessionChannel or IOutputChannel so that I can use the non-blocking BeginSend method. On my server, inside of the handler for the initiating method I have the following (I have tried every interface that I listed in place of IOutputChannel. None of them seem to exist.) _clientCb = OperationContext.Current.GetCallbackChannel<IDxClientCb>(); _channel = OperationContext.Current.Channel; _duplexChannel = _channel as IOutputChannel; Debug.Print("Service IOutputChannel null: {0}", _duplexChannel == null); Similarly, in the client I have tried to cast the return value of DuplexChannelFactory.CreateChannel() to any of these interfaces and I always get back a null. How do I get a reference to one of these?

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  • Merging code with dependencies? - Javascript

    - by RadiantHex
    Hi folks, this might be quite simple, but I must say I'm a bit confused on this topic. I'm writing code based on two popular libraries: jQuery underscore.js I am just wondering what would be the best way to isolate the code and prevent conflicts and how to merge it with its dependencies. By merging I mean putting them within the same file. :) I hope I'm not asking something which is too basic. ...and a last thing MERRY CHRISTMAS EVERYONE! =D

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  • Mocking methods that call other methods Still hit database.Can I avoid it?

    - by devnet247
    Hi, It has been decided to write some unit tests using moq etc..It's lots of legacy code c# (this is beyond my control so cannot answer the whys of this) Now how do you cope with a scenario when you dont want to hit the database but you indirectly still hit the database? This is something I put together it's not the real code but gives you an idea. How would you deal with this sort of scenario? Basically calling a method on a mocked interface still makes a dal call as inside that method there are other methods not part of that interface?Hope it's clear [TestFixture] public class Can_Test_this_legacy_code { [Test] public void Should_be_able_to_mock_login() { var mock = new Mock<ILoginDal>(); User user; var userName = "Jo"; var password = "password"; mock.Setup(x => x.login(It.IsAny<string>(), It.IsAny<string>(),out user)); var bizLogin = new BizLogin(mock.Object); bizLogin.Login(userName, password, out user); } } public class BizLogin { private readonly ILoginDal _login; public BizLogin(ILoginDal login) { _login = login; } public void Login(string userName, string password, out User user) { //Even if I dont want to this will call the DAL!!!!! var bizPermission = new BizPermission(); var permissionList = bizPermission.GetPermissions(userName); //Method I am actually testing _login.login(userName,password,out user); } } public class BizPermission { public List<Permission>GetPermissions(string userName) { var dal=new PermissionDal(); var permissionlist= dal.GetPermissions(userName); return permissionlist; } } public class PermissionDal { public List<Permission> GetPermissions(string userName) { //I SHOULD NOT BE GETTING HERE!!!!!! return new List<Permission>(); } } public interface ILoginDal { void login(string userName, string password,out User user); } public interface IOtherStuffDal { List<Permission> GetPermissions(); } public class Permission { public int Id { get; set; } public string Name { get; set; } } Any suggestions? Am I missing the obvious? Is this Untestable code? Very very grateful for any suggestions.

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  • How can I get the last-modified time with python3 urllib?

    - by Daenyth
    I'm porting over a program of mine from python2 to python3, and I'm hitting the following error: AttributeError: 'HTTPMessage' object has no attribute 'getdate' Here's the code: conn = urllib.request.urlopen(fileslist, timeout=30) last_modified = conn.info().getdate('last-modified') This section worked under python 2.7, and so far I haven't been able to find out the correct method to get this information in python 3.1. The full context is an update method. It pulls new files from a server down to its local database, but only if the file on the server is newer than the local file. If there's a smarter way to achieve this functionality than just comparing local and remote file timestamps, then I'm open to that as well.

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  • When does a PHP script end?

    - by allyourcode
    In my mind, a web app something that runs continuously; therefore, I'm confused by documentation pages that talk about the "end" of a PHP script (eg this one). Such references seem to refer to the end of each web request, but if the script ends there, doesn't that mean that the OS has to setup a whole new process for each request? That seems unlikely, because spinning up a whole new process is expensive, and be very inefficient for the whole site.

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