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  • Akima interpolation of an array of doubles

    - by David Rutten
    Assuming I have an array of doubles, what's a good algorithm to sample this series using Akima interpolation? I'm too stupid to translate that mathematical description into code. // values is an array of doubles // idx is the index of the left-hand value for the current interpolation // t is the normalized parameter between values[idx] and values[idx+1] // Don't worry about array bounds, I'll handle that separately. public double InterpolateAkima(double[] values, int idx, double t) { ...? }

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  • How can i interpret a time value in ascii into a numerical value?

    - by Bilal
    I have a file which is as follows: 15:03:21 II 0.88 0.64 15:03:31 II 0.88 0.64 15:03:42 II 0.40 0.40 etc. after loading the file in matlab, I want to be able to read the first column (which corresponds to time) and interpret them as numerical values. At the moment, they are interpreted as a string of ascii characters and i can't perform any mathematical operations on them. Does anyone have any suggestions as to how i can read the time as numbers instead of a string of ascii characters?

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  • P-NP-Problem: What are the most promising methods?

    - by phimuemue
    Hello everybody, I know that P=NP has not been solved up to now, but can anybody tell me something about the following: What are currently the most promising mathematical / computer scientific methods that could be helpful to tackle this problem? Or are there even none such methods known to be potentially helpful up to now? Is there any (free) compendium on this topic where I can find all / most of the research done in this area?

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  • cpu floating operations cost

    - by wiso
    I'm interesting in the time cost on a modern desktop cpu of some floating point operations in order to optimize a mathematical evaluation. In particular I'm interested on the comparison between complex operations like exp, log and simple operation like +, *, /. I tried to search for these information, but I can't find a source.

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  • For distributed applications, which to use, ASIO vs. MPI?

    - by Rhubarb
    I am a bit confused about this. If you're building a distributed application, which in some cases may perform parallel operations (although not necessarily mathematical), should you use ASIO or something like MPI? I take it MPI is a higher level than ASIO, but it's not clear where in the stack one would begin.

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  • P=NP?-Problem: What are the most promising methods?

    - by phimuemue
    Hello everybody, I know that P=NP has not been solved up to now, but can anybody tell me something about the following: What are currently the most promising mathematical / computer scientific methods that could be helpful to tackle this problem? Or are there even none such methods known to be potentially helpful up to now? Is there any (free) compendium on this topic where I can find all / most of the research done in this area?

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  • Why do we have so many programming-languages?

    - by ntsbjctve
    Most people would probably answer with "You won't build a house using only a hammer", but my argument against this is: There is also only one real mathematical language used for everything from chemical to architectural calculations, and as programming-languages are in many ways similar to maths, why should it be so different with them?

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  • Get more than 7 dimensions in google analytics

    - by Paritosh Singh
    I am fetching my data from google analytics core api. I came to know that we can fetch only 7 dimensions using api, But here I need to fetch more than 7 dimensions with correct metrics. Is there anyway (other than using paid google analytics) to fetch more than 7 dmensions with correct metrics from google analytics. If not, then is there any mathematical formula through which we can find intersection of dimensions fetched using 2 different dimensions having one dimension in common. Thanks

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  • deteminant of matrix

    - by davit-datuashvili
    suppose there is given two dimensional array int a[][]=new int[4][4]; i am trying to find determinant of matrices please help i know how find it mathematical but i am trying to find it in programaticaly

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  • Simple way to print value of a register in x86 assembly.

    - by Bob
    I need to write a program in 8086 Assembly that receives data from the user, does some mathematical calculations and prints the answer on the screen, I have written all parts of the program and all work fine but I don't know how to print the number to the screen. At the end of all my calculation the answer is AX and it is treated as an unsigned 16 bit integer. How do I print the decimal (unsigned) value of the AX register?

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  • Possible to distribute or parallel process a sequential program?

    - by damigu
    In C++, I've written a mathematical program (for diffusion limited aggregation) where each new point calculated is dependent on all of the preceding points. Is it possible to have such a program work in a parallel or distributed manner to increase computing speed? If so, what type of modifications to the code would I need to look into?

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  • Should I use "User Defined Functions" in SQL server, or C#?

    - by sanity
    I have a fairly complicated mathematical function that I've been advised should be implemented as a User Defined Function in SQL Server so that it can be used efficiently from within a SQL query. The problem is that it must be very efficient as it may be executed thousands of times per second, and I subsequently heard that UDFs are very inefficient. Someone suggested that I could implement the function in C# instead, and that this would be much more efficient. What should I do?

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  • How do call this symbolic code transformation ?

    - by erric
    Hi, I often cross this kind of code transformation (or even mathematical transformation) (python example, but applies to any language) I've go a function def f(x): return x I use it into another one. def g(x): return f(x)*f(x) print g(2) leads to 4 But I want to remove the functional dependency, and I change the function g into def g(f): return f*f print g( f(2) ) leads to 4 too How do you call this kind of transformation, locally turning a function into a scalar ?

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  • handling large number

    - by klw
    Hello, this is actually an problem question from project euler site http://projecteuler.net/index.php?section=problems&id=3 Anyway I'm not out after the solution, but I probably guess you will know what my approach is. To my question now, how do I handle numbers exceeding unsigned int? Is there a mathematical approach for this, if so where can I read about it?

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  • Extending Programming Languages

    - by chpwn
    (Since I just posted this in another question, but my browser had to be annoying and submit it without content first, here it is again:) I'm a fan of clean code. I like my languages to be able to express what I'm trying to do, but I like the syntax to mirror that too. For example, I work on a lot of programs in Objective-C for jailbroken iPhones, which patch other code using the method_setImplementation() function of the runtime. Or, in pyobjc, I have to use the syntax UIView.initWithFrame_(), which is also pretty awful and unreadable with the way the method names are structured. In both cases, the language does not support this in syntax. I've found three basic ways that this is done: Insane macros. Take a look at this "CaptainHook", it does what I'm looking for in a usable way, but it isn't quite clean and is a major hack. There's also "Logos", which implements a very nice syntax, but is written in Perl parsing my code with a ton of regular expressions. This scares me. I like the idea of adding a %hook ClassName, but not by using regular expressions to parse C or Objective-C. Finally, there is Cycript. This is an extension to JavaScript which interfaces with the Objective-C runtime and allows you to use Objective-C style code in your JavaScript, and inject that into other processes. This is likely the cleanest as it actually uses a parser for the JavaScript, but I'm not a huge fan of that language in general. Basically, this is a two part question. Should, and how should, I create an extension to Python and Objective-C to allow me to do this? Is it worth writing a parser for my language to transform the syntax into something nicer, if it is only in a very specialized niche like this? Should I just live with the horrible syntax of the default Objective-C hooking or pyobjc?

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  • Extract known pattern substring from NSString (without regex)

    - by d11wtq
    I'm really tempted to drop RegexKit (or my own libpcre wrapper) into my project in order to do this, but before I do that I want to know how Cocoa developers manage to do half of this basic stuff without really convoluted code or without linking with RegexKit or another regular expression library. I find it gobsmacking that Cocoa does not include any regular expression matching features. I've so accustomed to using regular expressions for all kinds of things that I'm lost without them. I can do what I need without them, but the code would be rather convoluted. So, Cocoa devs, I ask you, what's the "Cocoa way" to do this... The problem is an everyday problem in programming as far as I'm concerned. Cocoa must have ways of doing this with the built-in features. Note that the position of the elements I want to match changes, and sometimes "quotes" are present. Whitespace is variable. Take the following strings: Content-Type: application/xml; charset=utf-8 Content-Type: text/html; charset="iso-8859-1" Content-Type: text/plain; charset=us-ascii Content-Type: text/plain; name="example.txt"; charset=utf-8 From all of these strings, how would you go about determining the mime type (e.g. text/plain) and the charset (e.g. utf-8) using just the built-in Cocoa classes? I'd end up performing a series of -rangeOfString: and substring calls, with conditional checks to deal with the optional quotes etc. Is there a way to do this with NSScanner? The NSScanner class seems to have a pretty naive API to me. Something like C's sscanf() that works for NSString objects would be an ideal fit. Most of my string parsing needs are simple such as this example so maybe regular expressions, while I'm accustomed to them, are overkill?

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  • Extending Python and Objective-C

    - by chpwn
    I'm a fan of clean code. I like my languages to be able to express what I'm trying to do, but I like the syntax to mirror that too. For example, I work on a lot of programs in Objective-C for jailbroken iPhones, which patch other code using the method_setImplementation() function of the runtime. Or, in PyObjC, I have to use the syntax UIView.initWithFrame_(), which is also pretty awful and unreadable with the way the method names are structured. In both cases, the language does not support this in syntax. I've found three basic ways that this is done: Insane macros. Take a look at this "CaptainHook", it does what I'm looking for in a usable way, but it isn't quite clean and is a major hack. There's also "Logos", which implements a very nice syntax, but is written in Perl parsing my code with a ton of regular expressions. This scares me. I like the idea of adding a %hook ClassName, but not by using regular expressions to parse C or Objective-C. Finally, there is Cycript. This is an extension to JavaScript which interfaces with the Objective-C runtime and allows you to use Objective-C style code in your JavaScript, and inject that into other processes. This is likely the cleanest as it actually uses a parser for the JavaScript, but I'm not a huge fan of that language in general. Should, and how should, I create an extension to Python and Objective-C to allow me to do this? Is it worth writing a parser for my language to transform the syntax into something nicer, if it is only in a very specialized niche like this? Should I just live with the horrible syntax of the default Objective-C hooking or PyObjC?

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  • LinqKit System.InvalidCastException When Invoking method-provided expression on member property.

    - by mdworkin
    Given a simple parent/child class structure. I want to use linqkit to apply a child lambda expression on the parent. I also want the Lambda expression to be provided by a utility method. public class Foo { public Bar Bar { get; set; } } public class Bar { public string Value { get; set; } public static Expression<Func<Bar, bool>> GetLambdaX() { return c => c.Value == "A"; } } ... Expression<Func<Foo, bool>> lx = c => Bar.GetLambdaX().Invoke(c.Bar); Console.WriteLine(lx.Expand()); The above code throws System.InvalidCastException: Unable to cast object of type 'System.Linq.Expressions.MethodCallExpression' to type 'System.Linq.Expressions.LambdaExpression'. at LinqKit.ExpressionExpander.VisitMethodCall(MethodCallExpression m) at LinqKit.ExpressionVisitor.Visit(Expression exp) at LinqKit.ExpressionVisitor.VisitLambda(LambdaExpression lambda) at LinqKit.ExpressionVisitor.Visit(Expression exp) at LinqKit.Extensions.Expand<TDelegate>(Expression`1 expr) .... Please help!

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  • Having problems with sqlDataReader

    - by Anthony
    I am using a sqlDataReader to get data and set it to session variables. The problem is it doesn't want to work with expressions. I can reference any other column in the table, but not the expressions. The SQL does work. The code is below. Thanks in advance, Anthony Using myConnectionCheck As New SqlConnection(myConnectionString) Dim myCommandCheck As New SqlCommand() myCommandCheck.Connection = myConnectionCheck myCommandCheck.CommandText = "SELECT Projects.Pro_Ver, Projects.Pro_Name, Projects.TL_Num, Projects.LP_Num, Projects.Dev_Num, Projects.Val_Num, Projects.Completed, Flow.Initiate_Date, Flow.Requirements, Flow.Req_Date, Flow.Dev_Review, Flow.Dev_Review_Date, Flow.Interface, Flow.Interface_Date, Flow.Approval, Flow.Approval_Date, Flow.Test_Plan, Flow.Test_Plan_Date, Flow.Dev_Start, Flow.Dev_Start_Date, Flow.Val_Start, Flow.Val_Start_Date, Flow.Val_Complete, Flow.Val_Complete_Date, Flow.Stage_Production, Flow.Stage_Production_Date, Flow.MKS, Flow.MKS_Date, Flow.DIET, Flow.DIET_Date, Flow.Closed, Flow.Closed_Date, Flow.Dev_End, Flow.Dev_End_Date, Users_1.Email AS Expr1, Users_2.Email AS Expr2, Users_3.Email AS Expr3, Users_4.Email AS Expr4, Users_4.FNAME, Users_3.FNAME AS Expr5, Users_2.FNAME AS Expr6, Users_1.FNAME AS Expr7 FROM Projects INNER JOIN Users AS Users_1 ON Projects.TL_Num = Users_1.PIN INNER JOIN Users AS Users_2 ON Projects.LP_Num = Users_2.PIN INNER JOIN Users AS Users_3 ON Projects.Dev_Num = Users_3.PIN INNER JOIN Users AS Users_4 ON Projects.Val_Num = Users_4.PIN INNER JOIN Flow ON Projects.id = Flow.Flow_Pro_Num WHERE id = " myCommandCheck.CommandText += QSid myConnectionCheck.Open() myCommandCheck.ExecuteNonQuery() Dim count As Int16 = myCommandCheck.ExecuteScalar If count = 1 Then Dim myDataReader As SqlDataReader myDataReader = myCommandCheck.ExecuteReader() While myDataReader.Read() Session("TL_email") = myDataReader("Expr1").ToString() Session("PE_email") = myDataReader("Expr2").ToString() Session("DEV_email") = myDataReader("Expr3").ToString() Session("VAL_email") = myDataReader("Expr4").ToString() Session("Project_Name") = myDataReader("Pro_Name").ToString() End While myDataReader.Close() End If End Using

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