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• Writing fortran robust and "modern" code

  - by Blklight

  In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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• Objects in JavaScript defined and undefined at the same time (in a FireFox extension)

  - by Alexey Romanov

  I am chasing down a bug in a FireFox extension. I've finally managed to see it for myself (I've only had reports before) and I can't understand how what I saw is possible. One error message from my extension in the Error Console is "gBrowser is not defined". This by itself would be surprising enough, since the overlay is over browser.xul and navigator.xul, and I expect gBrowser to be available from both. Even worse is the actual place where it happens: line 101 of nextplease.js. That is, inside the function isTopLevelDocument, which is only called from onContentLoaded, which is only called from onLoad here: gBrowser.addEventListener(this.loadType, function (event) { nextplease.loadListener.onContentLoaded(event); }, true); So gBrowser is defined in onLoad, but somehow undefined in isTopLevelDocument. When I tried to actually use the extension, I got another error: "nextplease is not defined". The interesting thing is that it happened on lines 853 and 857. That is, inside the functions nextplease.getNextLink = function () { nextplease.getLink(window.content, nextplease.NextPhrasesMap, nextplease.NextImagesMap, nextplease.isNextRegExp, nextplease.NEXT_SEARCH_TYPE); } nextplease.getPrevLink = function () { nextplease.getLink(window.content, nextplease.PrevPhrasesMap, nextplease.PrevImagesMap, nextplease.isPrevRegExp, nextplease.PREV_SEARCH_TYPE); } So nextplease is somehow defined enough to call these functions, but isn't defined inside them. Finally, executing typeof(nextplease) in Execute JS returns "object". Same for gBrowser. How can this happen? Any ideas?

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• C# COM Cross Thread problem

  - by user364676

  Hi, we're developing a software to control a scientific measuring device. it provides a COM-Interface defines serveral functions to set measurement parameters and fires an event when it measured data. in order to test our software, i'm implementing a simulation of that device. the com-object runs a loop which periodically fires the event. another loop in the client app should now setup up the com-simulator using the given functions. i created a class for measuring parameters which will be instanciated when setting up a new measurement. // COM-Object public class MeasurementParams { public double Param1; public double Param2; } public class COM_Sim : ICOMDevice { public MeasurementParams newMeasurement; IClient client; public int NewMeasurement() { newMeasurment = new MeasurementParam(); } public int SetParam1(double val) { // why is newMeasurement null when method is called from client loop newMeasurement.Param1 = val; } void loop() { while(true) { // fire event client.HandleEvent; } } } public class Client : IClient { ICOMDevice server; public int HandleEvent() { // handle this event server.NewMeasurement(); server.SetParam1(0.0); } void loop() { while(true) { // do some stuff... server.NewMeasurement(); server.SetParam1(0.0); } } } both of the loops run in independent threads. when server.NewMeasurement() is called, the object on the server is set to a new instance. but in the next function, the object is null again. do the same when handling the server-event, it works perfectly, because the method runs in the servers thread. how to make it work from client-thread as well. as the client is meant to be working with the real device, i cannot modify the interfaces given by the manufactor. also i need to setup measurements independent from the event-handler, which will be fired not regulary. i assume this problem related to multithreaded-COM behavior but i found nothing on this topic.

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• What's the best way to transition to MVC coding?

  - by ggfan

  It's been around 5 months since I picked up a PHP book and started coding in PHP. At first, I created all my sites without any organizational plan or MVC. I soon found out that was a pain.. Then I started to read on stackoverflow on how to separate php and html and that's what I have been doing ever since. Ex: profile.php <--this file is HTML,css. I just echo the functions here. profile_functions.php <--this file is mostly PHP. has the functions. This is how I have been separating all my coding so far and now I feel I should move on and start MVC. But the problem is, I never used classes before and suck with them. And since MVC (such as cakephp and codeigniter) is all classes, that can't be good. My question: Is there any good books/sites/articles that teaches you how to code in MVC? I am looking for beginner beginner books :) I just started reading the codeigniter manuel and I think I am going to use that. When I looked at the example MVC, they use different PHP coding. When I start coding in MVC, would I have to learn a "new" way to code? Because right now I am coding in pure basic PHP.

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• Should I go vor 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 = false) Even more work to change all the CouchDB and Ajax functions but in the end I have better code.

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• What is the rationale to non allow overloading of C++ conversions operator with non-member functio

  - by Vicente Botet Escriba

  C++0x has added explicit conversion operators, but they must always be defined as members of the Source class. The same applies to the assignment operator, it must be defined on the Target class. When the Source and Target classes of the needed conversion are independent of each other, neither the Source can define a conversion operator, neither the Target can define a constructor from a Source. Usually we get it by defining a specific function such as Target ConvertToTarget(Source& v); If C++0x allowed to overload conversion operator by non member functions we could for example define the conversion implicitly or explicitly between unrelated types. template < typename To, typename From operator To(const From& val); For example we could specialize the conversion from chrono::time_point to posix_time::ptime as follows template < class Clock, class Duration operator boost::posix_time::ptime( const boost::chrono::time_point& from) { using namespace boost; typedef chrono::time_point time_point_t; typedef chrono::nanoseconds duration_t; typedef duration_t::rep rep_t; rep_t d = chrono::duration_cast( from.time_since_epoch()).count(); rep_t sec = d/1000000000; rep_t nsec = d%1000000000; return posix_time::from_time_t(0)+ posix_time::seconds(static_cast(sec))+ posix_time::nanoseconds(nsec); } And use the conversion as any other conversion. So the question is: What is the rationale to non allow overloading of C++ conversions operator with non-member functions?

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• Haskell math performance

  - by Travis Brown

  I'm in the middle of porting David Blei's original C implementation of Latent Dirichlet Allocation to Haskell, and I'm trying to decide whether to leave some of the low-level stuff in C. The following function is one example—it's an approximation of the second derivative of lgamma: double trigamma(double x) { double p; int i; x=x+6; p=1/(x*x); p=(((((0.075757575757576*p-0.033333333333333)*p+0.0238095238095238) *p-0.033333333333333)*p+0.166666666666667)*p+1)/x+0.5*p; for (i=0; i<6 ;i++) { x=x-1; p=1/(x*x)+p; } return(p); } I've translated this into more or less idiomatic Haskell as follows: trigamma :: Double -> Double trigamma x = snd $ last $ take 7 $ iterate next (x' - 1, p') where x' = x + 6 p = 1 / x' ^ 2 p' = p / 2 + c / x' c = foldr1 (\a b -> (a + b * p)) [1, 1/6, -1/30, 1/42, -1/30, 5/66] next (x, p) = (x - 1, 1 / x ^ 2 + p) The problem is that when I run both through Criterion, my Haskell version is six or seven times slower (I'm compiling with -O2 on GHC 6.12.1). Some similar functions are even worse. I know practically nothing about Haskell performance, and I'm not terribly interested in digging through Core or anything like that, since I can always just call the handful of math-intensive C functions through FFI. But I'm curious about whether there's low-hanging fruit that I'm missing—some kind of extension or library or annotation that I could use to speed up this numeric stuff without making it too ugly.

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• Complex derived attributes in Django models

  - by rabidpebble

  What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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• setInterval works only the first time

  - by Neil

  Hi, I am trying to use setTimer to animate a slide show using straightforward jQuery. I provide the user with a button (in the form of a "DIV" with a button background image) that he clicks to start the show and which then turns into a pause button. The slides are supposed to change every 3 seconds. Here is the relevant code: playLink = $('<div id="lbPlayLink" />').click(function(){ $(playLink).hide(); $(pauseLink).show(); slideInterval = setInterval(function(){next()}, 3000) })[0]; pauseLink = $('<div id="lbPauseLink" />').click(function(){ $(playLink).show(); $(pauseLink).hide(); clearInterval(slideInterval); }).hide()[0]; The next() function call does the work of replacing the slide with the next one. I have checked out this function and it works perfectly if I call it directly (synchronously), however, when it gets called asonchronously by the "setInterval", it works fine the first time (3 seconds after I click on the button), but is never called again, even though it should be called 3 seconds later. I know it's never called as I put an "alert" call at the beginning and end of the function. If I replace the "next()" call in the "setInterval" by "alert('test')" then I can see the setInterval is doing what it is supposed to. I can't for the life of me see why "alert()" is OK but "next()" isn't, unless it has something to do with "scope" of functions, but in that case why does it work the first time? I've tried debugging the code with firebug, but it can't really help with timeout functions like this. Neither Firefox nor IE8 show any error messages. I've looked through the various posts here and elsewhere on setInterval, but can't see anything relevant that I haven't tried already. I've been experimenting now for about 3 hours and it's doing my head in. Can anyone suggest what I can try next? Thanks in advance Neil

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• Python3 and ftplib uploading files

  - by Teifion

  My python2 script uploads files nicely using this method but python3 is presenting problems and I'm stuck as to where to go next (googling hasn't helped). from ftplib import FTP ftp = FTP(ftp_host, ftp_user, ftp_pass) ftp.storbinary('STOR myfile.txt', open('myfile.txt')) The error I get is Traceback (most recent call last): File "/Library/WebServer/CGI-Executables/rob3/functions/cli_f.py", line 12, in upload ftp.storlines('STOR myfile.txt', open('myfile.txt')) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 454, in storbinary conn.sendall(buf) TypeError: must be bytes or buffer, not str I tried altering the code to from ftplib import FTP ftp = FTP(ftp_host, ftp_user, ftp_pass) ftp.storbinary('STOR myfile.txt'.encode('utf-8'), open('myfile.txt')) But instead I got this Traceback (most recent call last): File "/Library/WebServer/CGI-Executables/rob3/functions/cli_f.py", line 12, in upload ftp.storbinary('STOR myfile.txt'.encode('utf-8'), open('myfile.txt')) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 450, in storbinary conn = self.transfercmd(cmd) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 358, in transfercmd return self.ntransfercmd(cmd, rest)[0] File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 329, in ntransfercmd resp = self.sendcmd(cmd) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 244, in sendcmd self.putcmd(cmd) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 179, in putcmd self.putline(line) File "/Library/Frameworks/Python.framework/Versions/3.1/lib/python3.1/ftplib.py", line 172, in putline line = line + CRLF TypeError: can't concat bytes to str Can anybody point me in the right direction

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• Multiple WCF calls for a single ASP.NET page load

  - by Rodney Burton

  I have an existing asp.net web application I am redesigning to use a service architecture. I have the beginnings of an WCF service which I am able to call and perform functions with no problems. As far as updating data, it all makes sense. For example, I have a button that says Submit Order, it sends the data to the service, which does the processing. Here's my concern: If I have an ASP.NET page that shows me a list of orders (View Orders page), and at the top I have a bunch of drop down lists for order types, and other search criteria which is populated by querying different tables from the database (lookup tables, etc). I am hoping to eventually completely decouple the web application from the DB, and use data contracts to pass information between the BLL, the SOA, and the web app. With that said, how can I reduce the # of WCF calls needed to load my "View Orders" page? I would need to make 1 call get the list of orders, and 1 call for each drop down list, etc because those are populated by individual functions in my BLL. Is it good architecture to create a web service method that returns back a specialized data contract that consists of everything you would need to display a View Orders page, in 1 shot? Something like this pseudocode: public class ViewOrderPageDTO { public OrderDTO[] Orders { get; set; } public OrderTypesDTO[] OrderTypes { get; set; } public OrderStatusesDTO[] OrderStatuses { get; set; } public CustomerListDTO[] CustomerList { get; set; } } Or is it better practice in the page_load event to make 5 or 6 or even 15 individual calls to the SOA to get the data needed to load the page? Therefore, bypassing the need for specialized wcf methods or DTO's that conglomerate other DTO? Thanks for your input and suggestions.

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• subtotals in columns usind reshape2 in R

  - by user1043144

  I have spent some time now learning RESHAPE2 and plyr but I still do not get it. This time I have a problem with (a) subtotals and (b) passing different aggregate functions . Here an example using data from the excellent tutorial on the blog of mrdwab http://news.mrdwab.com/ # libraries library(plyr) library(reshape2) # get data and add few more variables book.sales = read.csv("http://news.mrdwab.com/data-booksales") book.sales$Stock = book.sales$Quantity + 10 book.sales$SubjCat[(book.sales$Subject == 'Economics') | (book.sales$Subject == 'Management') ] <- '1_EconSciences' book.sales$SubjCat[book.sales$Subject %in% c('Anthropology', 'Politics', 'Sociology') ] <- '2_SocSciences' book.sales$SubjCat[book.sales$Subject %in% c('Communication', 'Fiction', 'History', 'Research', 'Statistics') ] <- '3_other' # to get to my starting dataframe (close to the project I am working on) book.sales1 <- ddply(book.sales, c('Region', 'Representative', 'SubjCat', 'Subject', 'Publisher'), summarize, Stock = sum(Stock), Sold = sum(Quantity), Ratio = round((100 * sum(Quantity)/ sum(Stock)), digits = 1)) #melt it m.book.sales = melt(data = book.sales1, id.vars = c('Region', 'Representative', 'SubjCat', 'Subject', 'Publisher'), measured.vars = c('Stock', 'Sold', 'Ratio')) # cast it Tab1 <- dcast(data = m.book.sales, formula = Region + Representative ~ Publisher + variable, fun.aggregate = sum, margins = c('Region', 'Representative')) Now my questions : I have been able to add the subtotals in rows. But is it possible also to add margins in the columns. Say for example, Totals of Stock for one Publisher ? Sorry I meant to say example total sold for all publishers There is a problem with the columns with “ratio”. How can I get “mean” instead of “sum” for this variable ? P.S: I have seen some examples using reshape. Will you recommend to use it instead of reshape2 (which seems not to include the functionalities of two functions).

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• jquery validate not submitting after modal close bootstrap

  - by Mariana Hernandez

  I have a modal where i insert some data, but when i open the modal, close it, and the click the modal show button again, it doesnt submit of course because the validate is "acting" in the modal, but i closed it so its not showing... how can i prevent this? thanks it is similar to this jquery functions within modal only work on first open, after close and re-open they stop working but my functions are <script> $(document).ready(function() { $("#myModal").modal('show'); }); </script> and the validation one <script> $(document).ready(function(){ $('#form1').validate( { ignore: "", rules: { usu_login: { required: true }, usu_password: { required: true }, usu_email: { required: true }, usu_nombre1: { required: true }, usu_apellido1: { required: true }, usu_fecha_nac: { required: true }, usu_cedula: { required: true }, usu_telefono1: { required: true }, rol_id: { required: true }, dependencia_id: { required: true }, }, highlight: function(element) { $(element).closest('.grupo').addClass('has-error'); if($(".tab-content").find("div.tab-pane.active:has(div.has-error)").length == 0) { $(".tab-content").find("div.tab-pane:hidden:has(div.has-error)").each(function(index, tab) { var id = $(tab).attr("id"); $('a[href="#' + id + '"]').tab('show'); }); } }, unhighlight: function(element) { $(element).closest('.grupo').removeClass('has-error'); } }); }); </script> So i dont know how to apply the answer of the above =(

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• Nusphere PHPEd: PHP Function Hints Lost Arguments?

  - by Eli

  Hi All, My PHPEd suddenly stopped showing arguments and arg order in the hints, and now just shows a basic description of the function. Before I go digging around in the config files, has anyone else had this problem? Thanks! Edit: Sorry, I may not have been entirely clear on this. There is no problem with my own classes, only with the actual php functions. Example: How it used to work: I type a PHP function, say strpos. As soon as I type the '(' at the end of it, I get the little yellow box, showing something like this: int strpos ( string $haystack , mixed $needle [, int $offset=0 ] ) with the first argument bold. If I type it, and then a comma, it bolds the second arg, and so on. This is really nice, since PHP functions are a bit scrambled as far as argument order, and I don't have to look them up every time. How it works now: I type a php function, say strpos. As soon as I type the '(' at the end of it, I get the little yellow box. It says something like "strpos - Returns the numeric position of the first occurrence of needle in the haystack string." There are no arguments shown, which makes the little box basically worthless - I know what strpos does, I just want a reminder of the argument order. I think this may be a problem with the included PHPDoc, which I never use, but may be the source of the data for the hint box. I did recently upgrade to 5.6, but ended up removing it and restoring 5.2. I installed to a different folder, and uninstalled from there, but it may have overwritten something in the original folder? I'm using v5.2 (5220). Thanks!

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• What am i doing wrong

  - by Erik Sapir

  I have the following code. I need B class to have a min priority queue of AToTime objects. AToTime have operator, and yet i receive error telling me than there is no operator matching the operands... #include <queue> #include <functional> using namespace std; class B{ //public functions public: B(); virtual ~B(); //private members private: log4cxx::LoggerPtr m_logger; class AToTime { //public functions public: AToTime(const ACE_Time_Value& time, const APtr a) : m_time(time), m_a(a){} bool operator >(const AToTime& other) { return m_time > other.m_time; } //public members - no point using any private members here public: ACE_Time_Value m_time; APtr m_a; }; priority_queue<AToTime, vector<AToTime>, greater<AToTime> > m_myMinHeap; };

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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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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