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  • performance of large number calculations in python (python 2.7.3 and .net 4.0)

    - by g36
    There is a lot of general questions about python performance in comparison to other languages. I've got more specific example: There are two simple functions wrote in python an c#, both checking if int number is prime. python: import time def is_prime(n): num =n/2 while num >1: if n % num ==0: return 0 num-=1 return 1 start = time.clock() probably_prime = is_prime(2147483629) elapsed = (time.clock() - start) print 'time : '+str(elapsed) and C#: using System.Diagnostics; public static bool IsPrime(int n) { int num = n/2; while(num >1) { if(n%num ==0) { return false; } num-=1; } return true; } Stopwatch sw = new Stopwatch(); sw.Start(); bool result = Functions.IsPrime(2147483629); sw.Stop(); Console.WriteLine("time: {0}", sw.Elapsed); And times ( which are surprise for me as a begginer in python:)): Python: 121s; c#: 6s Could You explain where does this big diffrence come from ?

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  • Setting Connection Parameters via ADO for MSSQL

    - by taspeotis
    Is it possible to set a connection parameter on a connection to SQL Server and have that variable persist throughout the life of the connection? The parameter must be usable by subsequent queries. We have some old Access reports that use a handful of VBScript functions in the SQL queries (let's call them GetStartDate and GetEndDate) that return global variables. Our application would set these before invoking the query and then the queries can return information between date ranges specified in our application. We are looking at changing to a ReportViewer control running in local mode, but I don't see any convenient way to use these custom functions in straight T-SQL. I have two concept solutions (not tested yet), but I would like to know if there is a better way. Below is some psuedo code. Set all variables before running Recordset.OpenForward Connection->Execute("SET @GetStartDate = ..."); Connection->Execute("SET @GetEndDate = ..."); // Repeat for all parameters Will these variables persist to later calls of Recordset->OpenForward? Can anything reset the variables aside from another SET/SELECT @variable statement? Create an ADOCommand "factory" that automatically adds parameters to each ADOCommand object I will use to execute SQL // Command has been previously been created ADOParameter *Parameter1 = Command->CreateParameter("GetStartDate"); ADOParameter *Parameter2 = Command->CreateParameter("GetEndDate"); // Set values and attach etc... What I would like to know if there is something like: Connection->SetParameter("GetStartDate", "20090101"); Connection->SetParameter("GetEndDate", 20100101"); And these will persist for the lifetime of the connection, and the SQL can do something like @GetStartDate to access them. This may be exactly solution #1, if the variables persist throughout the lifetime of the connection.

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  • Generating lognormally distributed random number from mean, coeff of variation

    - by Richie Cotton
    Most functions for generating lognormally distributed random numbers take the mean and standard deviation of the associated normal distribution as parameters. My problem is that I only know the mean and the coefficient of variation of the lognormal distribution. It is reasonably straight forward to derive the parameters I need for the standard functions from what I have: If mu and sigma are the mean and standard deviation of the associated normal distribution, we know that coeffOfVar^2 = variance / mean^2 = (exp(sigma^2) - 1) * exp(2*mu + sigma^2) / exp(mu + sigma^2/2)^2 = exp(sigma^2) - 1 We can rearrange this to sigma = sqrt(log(coeffOfVar^2 + 1)) We also know that mean = exp(mu + sigma^2/2) This rearranges to mu = log(mean) - sigma^2/2 Here's my R implementation rlnorm0 <- function(mean, coeffOfVar, n = 1e6) { sigma <- sqrt(log(coeffOfVar^2 + 1)) mu <- log(mean) - sigma^2 / 2 rlnorm(n, mu, sigma) } It works okay for small coefficients of variation r1 <- rlnorm0(2, 0.5) mean(r1) # 2.000095 sd(r1) / mean(r1) # 0.4998437 But not for larger values r2 <- rlnorm0(2, 50) mean(r2) # 2.048509 sd(r2) / mean(r2) # 68.55871 To check that it wasn't an R-specific issue, I reimplemented it in MATLAB. (Uses stats toolbox.) function y = lognrnd0(mean, coeffOfVar, sizeOut) if nargin < 3 || isempty(sizeOut) sizeOut = [1e6 1]; end sigma = sqrt(log(coeffOfVar.^2 + 1)); mu = log(mean) - sigma.^2 ./ 2; y = lognrnd(mu, sigma, sizeOut); end r1 = lognrnd0(2, 0.5); mean(r1) % 2.0013 std(r1) ./ mean(r1) % 0.5008 r2 = lognrnd0(2, 50); mean(r2) % 1.9611 std(r2) ./ mean(r2) % 22.61 Same problem. The question is, why is this happening? Is it just that the standard deviation is not robust when the variation is that wide? Or have a screwed up somewhere?

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  • Multiplication of 2 positive numbers giving a negative result

    - by krandiash
    My program is an implementation of a bloom filter. However, when I'm storing my hash function results in the bit array, the function (of the form f(i) = (a*i + b) % m where a,b,i,m are all positive integers) is giving me a negative result. The problem seems to be in the calculation of a*i which is coming out to be negative. Ignore the print statements in the code; those were for debugging. Basically, the value of temp in this block of code is coming out to be negative and so I'm getting an ArrayOutOfBoundsException. m is the bit array length, z is the number of hash functions being used, S is the set of values which are members of this bloom filter and H stores the values of a and b for the hash functions f1, f2, ..., fz. public static int[] makeBitArray(int m, int z, ArrayList<Integer> S, int[] H) { int[] C = new int[m]; for (int i = 0; i < z; i++) { for (int q = 0; q < S.size() ; q++) { System.out.println(H[2*i]); int temp = S.get(q)*(H[2*i]); System.out.println(temp); System.out.println(S.get(q)); System.out.println(H[2*i + 1]); System.out.println(m); int t = ((H[2*i]*S.get(q)) + H[2*i + 1])%m; System.out.println(t); C[t] = 1; } } return C; } Any help is appreciated.

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  • How would I send a POST Request via Ajax?

    - by Gotactics
    I have a php page, Post.php it recieves the POST's Action, and that has two functions. Insert, and Update.Now how would I go about posting INSERT with this Ajax code. The code posts update fine but is doesnt post insert at all. $(document).ready(function(){ //global vars var inputUser = $("#nick"); var inputMessage = $("#message"); var loading = $("#loading"); var messageList = $(".content ul"); //functions function updateShoutbox(){ //just for the fade effect messageList.hide(); loading.fadeIn(); //send the post to shoutbox.php $.ajax({ type: "POST", url: "Shoutbox.php", data: "action=update", complete: function(data){ loading.fadeOut(); messageList.html(data.responseText); messageList.fadeIn(2000); } }); } //check if all fields are filled function checkForm(){ if(inputUser.attr("value") && inputMessage.attr("value")) return true; else return false; } //Load for the first time the shoutbox data updateShoutbox(); //on submit event $("#form").submit(function(){ if(checkForm()){ var nick = inputUser.attr("value"); var message = inputMessage.attr("value"); //we deactivate submit button while sending $("#send").attr({ disabled:true, value:"Sending..." }); $("#send").blur(); //send the post to shoutbox.php $.ajax({ type: "GET", url: "Shoutbox.php", data: "action=insert&nick=" + nick + "&message=" + message, complete: function(data){ messageList.html(data.responseText); updateShoutbox(); //reactivate the send button $("#send").attr({ disabled:false, value:"Shout it!" }); } }); } else alert("Please fill all fields!"); //we prevent the refresh of the page after submitting the form return false; }); });emphasized text

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  • Excel Automation Addin UDFs not accesible

    - by Eric
    I created the following automation addin: namespace AutomationAddin { [Guid("6652EC43-B48C-428a-A32A-5F2E89B9F305")] [ClassInterface(ClassInterfaceType.AutoDual)] [ComVisible(true)] public class MyFunctions { public MyFunctions() { } #region UDFs public string ToUpperCase(string input) { return input.ToUpper(); } #endregion [ComRegisterFunctionAttribute] public static void RegisterFunction(Type type) { Registry.ClassesRoot.CreateSubKey( GetSubKeyName(type, "Programmable")); RegistryKey key = Registry.ClassesRoot.OpenSubKey( GetSubKeyName(type, "InprocServer32"), true); key.SetValue("", System.Environment.SystemDirectory + @"\mscoree.dll", RegistryValueKind.String); } [ComUnregisterFunctionAttribute] public static void UnregisterFunction(Type type) { Registry.ClassesRoot.DeleteSubKey( GetSubKeyName(type, "Programmable"), false); } private static string GetSubKeyName(Type type, string subKeyName) { System.Text.StringBuilder s = new System.Text.StringBuilder(); s.Append(@"CLSID\{"); s.Append(type.GUID.ToString().ToUpper()); s.Append(@"}\"); s.Append(subKeyName); return s.ToString(); } } } I build it and it registers just fine. I open excel 2003, go to tools-Add-ins, click on the automation button and the addin appears in the list. I add it and it shows up in the addins list. but, the functions themselves don't appear. If I type it in it doesn't work and if I look in the function wizard, my addin doesn't show up as a category and the functions are not in the list. I am using excel 2003 on windows 7 x86. I built the project with visual studio 2010. This addin worked fine on windows xp built with visual studio 2008.

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  • Calculating confidence intervals for a non-normal distribution

    - by Josiah
    Hi all, First, I should specify that my knowledge of statistics is fairly limited, so please forgive me if my question seems trivial or perhaps doesn't even make sense. I have data that doesn't appear to be normally distributed. Typically, when I plot confidence intervals, I would use the mean +- 2 standard deviations, but I don't think that is acceptible for a non-uniform distribution. My sample size is currently set to 1000 samples, which would seem like enough to determine if it was a normal distribution or not. I use Matlab for all my processing, so are there any functions in Matlab that would make it easy to calculate the confidence intervals (say 95%)? I know there are the 'quantile' and 'prctile' functions, but I'm not sure if that's what I need to use. The function 'mle' also returns confidence intervals for normally distributed data, although you can also supply your own pdf. Could I use ksdensity to create a pdf for my data, then feed that pdf into the mle function to give me confidence intervals? Also, how would I go about determining if my data is normally distributed. I mean I can currently tell just by looking at the histogram or pdf from ksdensity, but is there a way to quantitatively measure it? Thanks!

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  • Common lisp, CFFI, and instantiating c structs

    - by andrew
    Hi, I've been on google for about, oh, 3 hours looking for a solution to this "problem." I'm trying to figure out how to instantiate a C structure in lisp using CFFI. I have a struct in c: struct cpVect{cpFloat x,y;} Simple right? I have auto-generated CFFI bindings (swig, I think) to this struct: (cffi:defcstruct #.(chipmunk-lispify "cpVect" 'classname) (#.(chipmunk-lispify "x" 'slotname) :double) (#.(chipmunk-lispify "y" 'slotname) :double)) This generates a struct "VECT" with slots :X and :Y, which foreign-slot-names confirms (please note that I neither generated the bindings or programmed the C library (chipmunk physics), but the actual functions are being called from lisp just fine). I've searched far and wide, and maybe I've seen it 100 times and glossed over it, but I cannot figure out how to create a instance of cpVect in lisp to use in other functions. Note the function: cpShape *cpPolyShapeNew(cpBody *body, int numVerts, cpVect *verts, cpVect offset) Takes not only a cpVect, but also a pointer to a set of cpVects, which brings me to my second question: how do I create a pointer to a set of structs? I've been to http://common-lisp.net/project/cffi/manual/html_node/defcstruct.html and tried the code, but get "Error: Unbound variable: PTR" (I'm in Clozure CL), not to mention that looks to only return a pointer, not an instance. I'm new to lisp, been going pretty strong so far, but this is the first real problem I've hit that I can't figure out. Thanks!

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  • Setting Connection Parameters via ADO for SQL Server

    - by taspeotis
    Is it possible to set a connection parameter on a connection to SQL Server and have that variable persist throughout the life of the connection? The parameter must be usable by subsequent queries. We have some old Access reports that use a handful of VBScript functions in the SQL queries (let's call them GetStartDate and GetEndDate) that return global variables. Our application would set these before invoking the query and then the queries can return information between date ranges specified in our application. We are looking at changing to a ReportViewer control running in local mode, but I don't see any convenient way to use these custom functions in straight T-SQL. I have two concept solutions (not tested yet), but I would like to know if there is a better way. Below is some pseudo code. Set all variables before running Recordset.OpenForward Connection->Execute("SET @GetStartDate = ..."); Connection->Execute("SET @GetEndDate = ..."); // Repeat for all parameters Will these variables persist to later calls of Recordset->OpenForward? Can anything reset the variables aside from another SET/SELECT @variable statement? Create an ADOCommand "factory" that automatically adds parameters to each ADOCommand object I will use to execute SQL // Command has been previously been created ADOParameter *Parameter1 = Command->CreateParameter("GetStartDate"); ADOParameter *Parameter2 = Command->CreateParameter("GetEndDate"); // Set values and attach etc... What I would like to know if there is something like: Connection->SetParameter("GetStartDate", "20090101"); Connection->SetParameter("GetEndDate", 20100101"); And these will persist for the lifetime of the connection, and the SQL can do something like @GetStartDate to access them. This may be exactly solution #1, if the variables persist throughout the lifetime of the connection.

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  • Efficient Clojure workflow?

    - by Alex B
    I am developing a pet project with Clojure, but wonder if I can speed up my workflow a bit. My current workflow (with Compojure) is: Start Swank with lein swank. Go to Emacs, connect with M-x slime-connect. Load all existing source files one by one. This also starts a Jetty server and an application. Write some code in REPL. When satisfied with experiments, write a full version of a construct I had in mind. Eval (C-c C-c) it. Switch REPL to namespace where this construct resides and test it. Switch to browser and reload browser tab with the affected page. Tweak the code, eval it, check in the browser. Repeat any of the above. There are a number of annoyances with it: I have to switch between Emacs and the browser (or browsers if I am testing things like templating with multiple browsers) all the time. Is there a common idiom to automate this? I used to have a JavaScript bit that reloads the page continuously, but it's of limited utility, obviously, when I have to interact with the page for more than a few seconds. My JVM instance becomes "dirty" when I experiment and write test functions. Basically namespaces become polluted, especially if I'm refactoring and moving the functions between namespaces. This can lead to symbol collisions and I need to restart Swank. Can I undef a symbol? I load all source files one by one (C-c C-k) upon restarting Swank. I suspect I'm doing it all wrong. Switching between the REPL and the file editor can be a bit irritating, especially when I have a lot of Emacs tabs open, alongside the browser(s). I'm looking for ways to improve the above points and the entire workflow in general, so I'd appreciate if you'd share yours. P. S. I have also used Vimclojure before, so Vimclojure-based workflows are welcome too.

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  • Php index page utitlizing an idea for a superswitch...

    - by Matt
    I dont know if this is a great idea...or a crap one. But I was thinking I may use one page to display all my pages using includes. Here is what my index.php would look like...on the functions include there is a function called "superSwitch" which will determine what requested page will be included....for instance if I do a get ?a=a it will goto the function superSwitch(a) superSwitch will take it and associate it with (login.php) then respond with such... here is the code for the index.php...please let me know if this makes sense and might work, or should I just stick to long blocks of code (which is why I am trying this because I hate long pages full of code...) of course as you can tell it is not actually including anything yet...the print is for debugging purposes. :) Thanks, Matt <?php //includes Functions include_once('inc/func.inc.php'); //set superget variable $superget = @$_GET['a']; //check if superget is set or null if (!$superget) { echo "Nothing Requested :)"; } else { //sanitizes the superget request $supergetr = supergetSanitize($superget) //uses the result "good" or "nogood" to determine what happens if ( $supergetr == "good" ) { //pulls superSwitch value of the request $ssresult = superSwitch($superget); print_r ($ssresult); } //if the sanitize is nogood else { //the superSwitch is instructed to respond with a 404 page $superget = "404" $ssresult = superSwitch($superget); print_r ($ssresult); } } ?>

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  • SQL Server database change workflow best practices

    - by kubi
    The Background My group has 4 SQL Server Databases: Production UAT Test Dev I work in the Dev environment. When the time comes to promote the objects I've been working on (tables, views, functions, stored procs) I make a request of my manager, who promotes to Test. After testing, she submits a request to an Admin who promotes to UAT. After successful user testing, the same Admin promotes to Production. The Problem The entire process is awkward for a few reasons. Each person must manually track their changes. If I update, add, remove any objects I need to track them so that my promotion request contains everything I've done. In theory, if I miss something testing or UAT should catch it, but this isn't certain and it's a waste of the tester's time, anyway. Lots of changes I make are iterative and done in a GUI, which means there's no record of what changes I made, only the end result (at least as far as I know). We're in the fairly early stages of building out a data mart, so the majority of the changes made, at least count-wise, are minor things: changing the data type for a column, altering the names of tables as we crystallize what they'll be used for, tweaking functions and stored procs, etc. The Question People have been doing this kind of work for decades, so I imagine there have got to be a much better way to manage the process. What I would love is if I could run a diff between two databases to see how the structure was different, use that diff to generate a change script, use that change script as my promotion request. Is this possible? If not, are there any other ways to organize this process? For the record, we're a 100% Microsoft shop, just now updating everything to SQL Server 2008, so any tools available in that package would be fair game.

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  • Handling missing/incomplete data in R--is there function to mask but not remove NAs?

    - by doug
    As you would expect from a DSL aimed at data analysis, R handles missing/incomplete data very well, for instance: Many R functions have an 'na.rm' flag that you can set to 'T' to remove the NAs: mean( c(5,6,12,87,9,NA,43,67), na.rm=T) But if you want to deal with NAs before the function call, you need to do something like this: to remove each 'NA' from a vector: vx = vx[!is.na(a)] to remove each 'NA' from a vector and replace it w/ a '0': ifelse(is.na(vx), 0, vx) to remove entire each row that contains 'NA' from a data frame: dfx = dfx[complete.cases(dfx),] All of these functions permanently remove 'NA' or rows with an 'NA' in them. Sometimes this isn't quite what you want though--making an 'NA'-excised copy of the data frame might be necessary for the next step in the workflow but in subsequent steps you often want those rows back (e.g., to calculate a column-wise statistic for a column that has missing rows caused by a prior call to 'complete cases' yet that column has no 'NA' values in it). to be as clear as possible about what i'm looking for: python/numpy has a class, 'masked array', with a 'mask' method, which lets you conceal--but not remove--NAs during a function call. Is there an analogous function in R?

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  • Adding XOR function to bigint library

    - by Jason Gooner
    Hi, I'm using this Big Integer library for Javascript: http://www.leemon.com/crypto/BigInt.js and I need to be able to XOR two bigInts together and sadly the library doesn't include such a function. The library is relatively simple so I don't think it's a huge task, just confusing. I've been trying to hack one together but not having much luck, would be very grateful if someone could lend me a hand. This is what I've attempted (might be wrong). But im guessing the structure is going to be quite similar to some of the other functions in there. function xor(x, y) { var c, k, i; var result = new Array(0); // big int for result k=x.length>y.length ? x.length : y.length; // array length of the larger num // Make sure result is the correct array size? maybe: result = expand(result, k); // ? for (c=0, i=0; i < k; i++) { // Do some xor here } // return the bigint xor result return result; } What confuses me is I don't really understand how it stores numbers in the array blocks for the bigInt. I don't think it's a case of simply bigintC[i] = bigintA[i] ^ bigintB[i], then most other functions have some masking operation at the end that I don't understand. I would really appreciate any help getting this working. Thanks

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  • Using unset member variables within a class or struct

    - by Doug Kavendek
    It's pretty nice to catch some really obvious errors when using unset local variables or when accessing a class or struct's members directly prior to initializing them. In visual studio 2008 you get an "uninitialized local variable used" warning at compile-time and get a run-time check failure at the point of access when debugging. However, if you access an uninitialized struct's member variable through one of its functions, you don't get any warnings or assertions. Obviously the easiest solution is don't do that, but nobody's perfect. For example: struct Test { float GetMember() const { return member; } float member; }; Test test; float f1 = test.member; // Raises warning, asserts in VS debugger at runtime float f2 = test.GetMember(); // No problem, just keeps on going This surprised me, but it makes some sense -- the compiler can't assume calling a function on an unused struct is an error, or how else would you initialize or construct it? And anything fancier just quickly brings up so many other complications that it makes sense that it wouldn't bother classifying which functions are ok to call and when, especially just as a debugging help. I know I can set up my own assertions or error checking within the class itself, but that can complicate some simpler structs. Still, it would seem like within the context of the function call, wouldn't it know insides GetMember() that member wasn't initialized yet? I'm assuming it's not only relying on static compile-time deduction, given the Run-Time Check Failure #3 it raises during execution, so based on my current understanding of it it would seem reasonable for the same checks to apply. Is this just a limitation of this specific compiler/debugger (Visual Studio 2008), or more tied to how C++ works?

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  • Moving inserted container element if possible

    - by doublep
    I'm trying to achieve the following optimization in my container library: when inserting an lvalue-referenced element, copy it to internal storage; but when inserting rvalue-referenced element, move it if supported. The optimization is supposed to be useful e.g. if contained element type is something like std::vector, where moving if possible would give substantial speedup. However, so far I was unable to devise any working scheme for this. My container is quite complicated, so I can't just duplicate insert() code several times: it is large. I want to keep all "real" code in some inner helper, say do_insert() (may be templated) and various insert()-like functions would just call that with different arguments. My best bet code for this (a prototype, of course, without doing anything real): #include <iostream> #include <utility> struct element { element () { }; element (element&&) { std::cerr << "moving\n"; } }; struct container { void insert (const element& value) { do_insert (value); } void insert (element&& value) { do_insert (std::move (value)); } private: template <typename Arg> void do_insert (Arg arg) { element x (arg); } }; int main () { { // Shouldn't move. container c; element x; c.insert (x); } { // Should move. container c; c.insert (element ()); } } However, this doesn't work at least with GCC 4.4 and 4.5: it never prints "moving" on stderr. Or is what I want impossible to achieve and that's why emplace()-like functions exist in the first place?

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  • contenteditable selected text save and restore

    - by alex
    I came across this post that shows 2 functions on how to save and restore selected text from a contenteditable div. I have the below div set as contenteditable and the 2 function from the other post. How to i use these functions to save and restore selected text. <div style="width:300px;padding:10px;" contenteditable="true">test test test test</div> <script> function saveSelection() { if (window.getSelection) { sel = window.getSelection(); if (sel.getRangeAt && sel.rangeCount) { return sel.getRangeAt(0); } } else if (document.selection && document.selection.createRange) { return document.selection.createRange(); } return null; } function restoreSelection(range) { if (range) { if (window.getSelection) { sel = window.getSelection(); sel.removeAllRanges(); sel.addRange(range); } else if (document.selection && range.select) { range.select(); } } } </script>

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  • Is extending a base class with non-virtual destructor dangerous in C++

    - by Akusete
    Take the following code class A { }; class B : public A { }; class C : public A { int x; }; int main (int argc, char** argv) { A* b = new B(); A* c = new C(); //in both cases, only ~A() is called, not ~B() or ~C() delete b; //is this ok? delete c; //does this line leak memory? return 0; } when calling delete on a class with a non-virtual destructor with member functions (like class C), can the memory allocator tell what the proper size of the object is? If not, is memory leaked? Secondly, if the class has no member functions, and no explicit destructor behaviour (like class B), is everything ok? I ask this because I wanted to create a class to extend std::string, (which I know is not recommended, but for the sake of the discussion just bear with it), and overload the +=,+ operator. -Weffc++ gives me a warning because std::string has a non virtual destructor, but does it matter if the sub-class has no members and does not need to do anything in its destructor? -- FYI the += overload was to do proper file path formatting, so the path class could be used like class path : public std::string { //... overload, +=, + //... add last_path_component, remove_path_component, ext, etc... }; path foo = "/some/file/path"; foo = foo + "filename.txt"; //and so on... I just wanted to make sure someone doing this path* foo = new path(); std::string* bar = foo; delete bar; would not cause any problems with memory allocation

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  • Scheme: what are the benefits of letrec?

    - by Ixmatus
    While reading "The Seasoned Schemer" I've begun to learn about letrec. I understand what it does (can be duplicated with a Y-Combinator) but the book is using it in lieu of recurring on the already defined function operating on arguments that remain static. An example of an old function using the defined function recurring on itself (nothing special): (define (substitute new old lat) (cond ((null? l) '()) ((eq? (car l) old) (cons new (substitute new old (cdr l)))) (else (cons (car l) (substitute new old (cdr l)))))) Now for an example of that same function but using letrec: (define (substitute new old lat) (letrec ((replace (lambda (l) (cond ((null? l) '()) ((eq? (car l) old) (cons new (replace (cdr l)))) (else (cons (car l) (replace (cdr l)))))))) (replace lat))) Aside from being slightly longer and more difficult to read I don't know why they are rewriting functions in the book to use letrec. Is there a speed enhancement when recurring over a static variable this way because you don't keep passing it?? Is this standard practice for functions with arguments that remain static but one argument that is reduced (such as recurring down the elements of a list)? Some input from more experienced Schemers/LISPers would help!

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  • Why is my PHP string being converted to 1?

    - by animuson
    Ok, so here's the quick rundown. I have a function to generate the page numbers. This: <?php die($ani->e->tmpl->pages("/archive", 1, 15, 1, true)); ?> will output Single Page like expected. But this: <?php $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ?> <?= $page_numbers ?> will output a simple 1 to the page. Why is it getting converted to a 1? I would expect it to store the 'Single Page' string to the page_numbers variable and then output it (like an echo) exactly the same. EDIT: Running a var_dump($page_numbers) returns int(1)... Here is the entire function in context: <?php // other functions... function show_list() { global $ani; $page_numbers = $ani->e->tmpl->pages("/archive", 1, 15, 1, true); ob_start(); ?> <!-- content:start --> <?php $archive_result = $ani->e->db->build(array("select" => "*", "from" => "animuson_archive", "orderby" => "0-time", "limit" => 15)); while ($archive = $ani->e->db->fetch($archive_result)) { ?> <h2><a href="/archive/article/<?= $archive['aid'] ?>/<?= $archive['title_nice'] ?>"><?= $archive['title'] ?></a></h2> <!-- breaker --> <?php } ?> <?= var_dump($page_numbers) ?> <!-- content:stop --> <?php $ani->e->tmpl->process("box", ob_get_clean()); } // other functions... ?>

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  • Database Functional Programming in Clojure

    - by Ralph
    "It is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail." - Abraham Maslow I need to write a tool to dump a large hierarchical (SQL) database to XML. The hierarchy consists of a Person table with subsidiary Address, Phone, etc. tables. I have to dump thousands of rows, so I would like to do so incrementally and not keep the whole XML file in memory. I would like to isolate non-pure function code to a small portion of the application. I am thinking that this might be a good opportunity to explore FP and concurrency in Clojure. I can also show the benefits of immutable data and multi-core utilization to my skeptical co-workers. I'm not sure how the overall architecture of the application should be. I am thinking that I can use an impure function to retrieve the database rows and return a lazy sequence that can then be processed by a pure function that returns an XML fragment. For each Person row, I can create a Future and have several processed in parallel (the output order does not matter). As each Person is processed, the task will retrieve the appropriate rows from the Address, Phone, etc. tables and generate the nested XML. I can use a a generic function to process most of the tables, relying on database meta-data to get the column information, with special functions for the few tables that need custom processing. These functions could be listed in a map(table name -> function). Am I going about this in the right way? I can easily fall back to doing it in OO using Java, but that would be no fun. BTW, are there any good books on FP patterns or architecture? I have several good books on Clojure, Scala, and F#, but although each covers the language well, none look at the "big picture" of function programming design.

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  • Should I go for Arrays or Objects in PHP in a CouchDB/Ajax app?

    - by karlthorwald
    I find myself converting between array and object all the time in PHP application that uses couchDB and Ajax. Of course I am also converting objects to JSON and back (for sometimes couchdb but mostly Ajax), but this is not so much disturbing my workflow. At the present I have php objects that are returned by the CouchDB modules I use and on the other hand I have the old habbit to return arrays like array("error"="not found","data"=$dataObj) from my functions. This leads to a mixed occurence of real php objects and nested arrays and I cast with (object) or (array) if necessary. The worst thing is that I know more or less by heart what a function returns, but not what type (array or object), so I often run into type errors. My plan is now to always cast arrays to objects before returning from a function. Of course this implies a lot of refactoring. Is this the right way to go? What about the conversion overhead? Other ideas or tips? Edit: Kenaniah's answer suggests I should go the other way, this would mean I'd cast everything to arrays. And for all the Ajax / JSON stuff and also for CouchDB I would use $myarray = json_decode($json_data,$assoc = true); //EDIT: changed to true, whcih is what I really meant Even more work to change all the CouchDB and Ajax functions but in the end I have better code.

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  • How to define a "complicated" ComputedColumn in SQL Server?

    - by Slauma
    SQL Server Beginner question: I'm trying to introduce a computed column in SQL Server (2008). In the table designer of SQL Server Management Studio I can do this, but the designer only offers me one single edit cell to define the expression for this column. Since my computed column will be rather complicated (depending on several database fields and with some case differentiations) I'd like to have a more comfortable and maintainable way to enter the column definition (including line breaks for formatting and so on). I've seen there is an option to define functions in SQL Server (scalar value or table value functions). Is it perhaps better to define such a function and use this function as the column specification? And what kind of function (scalar value, table value)? To make a simplified example: I have two database columns: DateTime1 (smalldatetime, NULL) DateTime2 (smalldatetime, NULL) Now I want to define a computed column "Status" which can have four possible values. In Dummy language: if (DateTime1 IS NULL and DateTime2 IS NULL) set Status = 0 else if (DateTime1 IS NULL and DateTime2 IS NOT NULL) set Status = 1 else if (DateTime1 IS NOT NULL and DateTime2 IS NULL) set Status = 2 else set Status = 3 Ideally I would like to have a function GetStatus() which can access the different column values of the table row which I want to compute the value of "Status" for, and then only define the computed column specification as GetStatus() without parameters. Is that possible at all? Or what is the best way to work with "complicated" computed column definitions? Thank you for tips in advance!

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  • Slow Python HTTP server on localhost

    - by Abiel
    I am experiencing some performance problems when creating a very simple Python HTTP server. The key issue is that performance is varying depending on which client I use to access it, where the server and all clients are being run on the local machine. For instance, a GET request issued from a Python script (urllib2.urlopen('http://localhost/').read()) takes just over a second to complete, which seems slow considering that the server is under no load. Running the GET request from Excel using MSXML2.ServerXMLHTTP also feels slow. However, requesting the data Google Chrome or from RCurl, the curl add-in for R, yields an essentially instantaneous response, which is what I would expect. Adding further to my confusion is that I do not experience any performance problems for any client when I am on my computer at work (the performance problems are on my home computer). Both systems run Python 2.6, although the work computer runs Windows XP instead of 7. Below is my very simple server example, which simply returns 'Hello world' for any get request. from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer class MyHandler(BaseHTTPRequestHandler): def do_GET(self): print("Just received a GET request") self.send_response(200) self.send_header("Content-type", "text/html") self.end_headers() self.wfile.write('Hello world') return def log_request(self, code=None, size=None): print('Request') def log_message(self, format, *args): print('Message') if __name__ == "__main__": try: server = HTTPServer(('localhost', 80), MyHandler) print('Started http server') server.serve_forever() except KeyboardInterrupt: print('^C received, shutting down server') server.socket.close() Note that in MyHandler I override the log_request() and log_message() functions. The reason is that I read that a fully-qualified domain name lookup performed by one of these functions might be a reason for a slow server. Unfortunately setting them to just print a static message did not solve my problem. Also, notice that I have put in a print() statement as the first line of the do_GET() routine in MyHandler. The slowness occurs prior to this message being printed, meaning that none of the stuff that comes after it is causing a delay.

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  • Javascript Confirm Delete in One PHP File (on href)

    - by gamerzfuse
    <p><span class="linky"><a href="deletephone.php?id=' . $row['id'] . '">Delete Phone</a></span></p><br /> I have the above code that I am using to link to a delete script. I want to somehow incorporate Javascript with a simple onclick confirmation. This way if they choose OK, I can run the code to delete the item from the database, but if they choose Cancel then I can cancel the operation and do nothing. I have tried a whole variety of functions with changing the window.location to the delete file, and trying to cancel the href= if they choose Cancel, but it always goes to the link regardless of what the user clicks. I would like to be able to keep the delete functions inside the same PHP file if possible, but this is not necessary at all. Thanks in advance! ASIDE: If there is a simple PHP way to check IF the alert was confirmed or denied, that could work also. Any way to check what the user chooses and then run my simple delete PHP command.

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