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• ILNumerics multiply complex with matrix<double>

  - by nik

  I m looking at ILNumerics to translate some matlab code into c#. How would I multiply a complex and a double? Simplified description: In Matlab: A=[1 2 3] i*A*A' Returns a complex number. How would I do the same in ILNumerics: ILArray<double> A = ILMath.array(1.0, 2.0, 3.0); complex B = complex.i * ILMath.multiply(A,A.T); Throws the error: Operator '*' cannot be applied to operands of type 'ILNumerics.complex' and 'ILNumerics.ILRetArray<double>' Update This works: double C = 14.0; complex D = complex.i * C; But shouldnt: ILMath.multiply(A,A.T) also return 14.0?

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• Simple prime number program - Weird issue with threads C#

  - by Para

  Hi! This is my code: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; namespace FirePrime { class Program { static bool[] ThreadsFinished; static bool[] nums; static bool AllThreadsFinished() { bool allThreadsFinished = false; foreach (var threadFinished in ThreadsFinished) { allThreadsFinished &= threadFinished; } return allThreadsFinished; } static bool isPrime(int n) { if (n < 2) { return false; } if (n == 2) { return true; } if (n % 2 == 0) { return false; } int d = 3; while (d * d <= n) { if (n % d == 0) { return false; } d += 2; } return true; } static void MarkPrimes(int startNumber,int stopNumber,int ThreadNr) { for (int j = startNumber; j < stopNumber; j++) nums[j] = isPrime(j); lock (typeof(Program)) { ThreadsFinished[ThreadNr] = true; } } static void Main(string[] args) { int nrNums = 100; int nrThreads = 10; //var threadStartNums = new List<int>(); ThreadsFinished = new bool[nrThreads]; nums = new bool[nrNums]; //var nums = new List<bool>(); nums[0] = false; nums[1] = false; for(int i=2;i<nrNums;i++) nums[i] = true; int interval = (int)(nrNums / nrThreads); //threadStartNums.Add(2); //int aux = firstStartNum; //int i = 2; //while (aux < interval) //{ // aux = interval*i; // i=i+1; // threadStartNums.Add(aux); //} int startNum = 0; for (int i = 0; i < nrThreads; i++) { var _thread = new System.Threading.Thread(() => MarkPrimes(startNum, Math.Min(startNum + interval, nrNums), i)); startNum = startNum + interval; //set the thread to run in the background _thread.IsBackground = true; //start our thread _thread.Start(); } while (!AllThreadsFinished()) { Thread.Sleep(1); } for (int i = 0; i < nrNums; i++) if(nums[i]) Console.WriteLine(i); } } } This should be a pretty simple program that is supposed to find and output the first nrNums prime numbers using nrThreads threads working in parallel. So, I just split nrNums into nrThreads equal chunks (well, the last one won't be equal; if nrThreads doesn't divide by nrNums, it will also contain the remainder, of course). I start nrThreads threads. They all test each number in their respective chunk and see if it is prime or not; they mark everything out in a bool array that keeps a tab on all the primes. The threads all turn a specific element in another boolean array ThreadsFinished to true when they finish. Now the weird part begins: The threads never all end. If I debug, I find that ThreadNr is not what I assign to it in the loop but another value. I guess this is normal since the threads execute afterwards and the counter (the variable i) is already increased by then but I cannot understand how to make the code be right. Can anyone help? Thank you in advance. P.S.: I know the algorithm is not very efficient; I am aiming at a solution using the sieve of Eratosthenes also with x given threads. But for now I can't even get this one to work and I haven't found any examples of any implementations of that algorithm anywhere in a language that I can understand.

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• Using Where method in Linq 2 Entities with OR clause.

  - by Dani

  I want to use Where method in Linq 2 entities that will be equal to this userRepository.Users.Where(u=>u.RoleID == 1 || u=>u.RoldID == 2).Select(o => new SelectListItem { Text = o.Role.RoleName, Value = o.RoleID.ToString() }).ToList(); The problem of course is in Where(u=u.RoleID == 1 || u=u.RoldID == 2) The problem is that I don't know how to use WHERE method with OR inside the WHERE clause. any ideas (the code above will not compile of-course b/c of the lambda expression. userRepository.Users returns an list of Users entities. I guess that and can be done using concatenation of .Where().Where() but I need an OR.

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• PHP - Using strcpsn() to protect against SQL injection?

  - by MichaelMitchell

  I am making a sort of form validation system and I need to check the SQL database to see if the username is already there. So, my question, is it effective to use a little if statement like this to protect against an attack? if (strcspn($string, "/\?!@#$%^&*()[]{}|:;<>,.\"\'-+=" == strlen($string)){ return true; } So essentially, if the string contains any of these characters, "/\?!@#$%^&*()[]{}|:;<>,.\"\'-+=", then the length will not equal that of the original $string. I am just wondering if this is sufficient to protect, or if there is more that I must do. Thanks.

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• array loop not working correctly? c++

  - by igor

  Trying to count how many elements within the array are not equal to 0, is something set up wrong? I'd like to check all values in the array (it's a sudoku board) and then when all elements are "full" I need to return true. Is something off? bool boardFull(const Square board[BOARD_SIZE][BOARD_SIZE]) { int totalCount=0; for (int index1 = 0; index1 < BOARD_SIZE; index1++) for (int index2 = 0; index2 < BOARD_SIZE; index2++){ if(board[index1][index2].number!=0) totalCount++; } if(totalCount=81) return true; else return false;

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• Extended maxima transform in Matlab

  - by garvin

  I use imtophat to apply a filter to an m x n array. I then find the local max using imextendedmax(). I get mostly 0's everywhere except for 1's in the general areas where I am expecting a local max. The weird thing is, though, that I don't get just one local max. Instead in these places I get MANY elements with 1's such as 00011100000 00111111000 00000110000 yet the values there are close but NOT equal so I would expect that there would be one that is higher than all of the rest. So I'm wondering a) if this is a bug and how I might fix it and b) how you would choose choose the element of these 1's with the highest value.

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• Facebook FB.api post how to specify a target

  - by Laurent Luce

  I am using FB.api OpenGraph to post a message on the user's wall. I would like the link target to be equal to '_blank' so it opens in a new tab. Is it possible ? The Facebook documentation doesn't give much details. var params = {}; params['message'] = 'message'; params['name'] = 'name'; params['link'] = 'http://link'; params['picture'] = 'http://picture'; params['description'] = 'description'; FB.api('/me/feed', 'post', params, function(response) { if (!response || response.error) { alert('Error occured'); } else { alert('Post ID: ' + response); } });

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• How to show a page after a specific time period?

  - by Mahfuz

  I want to build an online quiz test site. Suppose, exam will start at 10:00 am and a student login to give exam at 9:45 am. Whenever the student clicks 'Take Exam' button, he/she cannot not get access to the question paper because the exam time is 10:00 am and there are still 15 minutes before the exam start. Now I want to put some Javascript or PHP code that will prohibit the students to give exam earlier and if a students come early, it will show a stopwatch which display the remaining time before exam time and when the current time is equal to exam time then he/she will be directly redirected to the question paper page.

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• JQuery multiple-choice quiz script: how to ensure the correct answer is available?

  - by DavidR

  I have a function. I pass to it an object with a list of questions and answers. I generate a random number from a range equal to the number of questions in the object. The script check to see if that question has been asked, and if not, it asks it, the correct answer is then passed to a variable correct. I want to give 4 possible answers, each one randomly selected from the list of possible answers. I have this. I just want to know what is the best way to ensure that the correct answer is placed in the list. So far, this is what I have: it puts four answers into four targeted boxes. I want to ensure that the correct answer is in a randomly selected box. function getRandom(limit) { return Math.floor(Math.random() * limit ) } $("#answers > .answer").each(function(i){ r = getRandom(total_questions); $(this).text(answers[r]) });

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• hierarchical data from self referencing table in tree form

  - by Beta033

  It looks like this has been asked and answered in all the simple cases, excluding the one that I'm having trouble with. I've tried using a recursive CTE to generate this; however maybe a cursor would be better? Or maybe a set of recursive functions will do the trick? Can this be done in a cte? consider the following table PrimaryKey ParentKey 1 NULL 2 1 3 6 4 7 5 2 6 1 7 NULL should yield PK 1 -2 --5 -6 --3 7 -4 where the number of - marks equal the depth, my primary difficulty is the ordering.

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• Force an object to be allocated on the heap

  - by Warren Seine

  A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

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• Mixing LINQ to SQL with properties of objects in a generic list

  - by BPotocki

  I am trying to accomplish something like this query: var query = from a in DatabaseTable where listOfObjects.Any(x => x.Id == a.Id) select a; Basically, I want to filter the results where a.Id equals a property of one of the objects in the generic list "listOfObjects". I'm getting the error "Local sequence cannot be used in LINQ to SQL implementation of query operators except the Contains() operator." Any ideas on how to filter this in an easily readable way using "contains" or another method? Thanks in advance.

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• Purpose of IF, ELSE, FOR macros ?

  - by psihodelia

  I have a source code of a library which has a lot of strange IF, ELSE, FOR, etc. macros for all common C-keywords instead of using just usual if,else,for,while keywords. These macros are defined like this: #define IF( a) if( increment_if(), a) where increment_if() function is defined so: static __inline void increment_if( void) { // If the "IF" operator comes just after an "ELSE", its counter // must not be incremented. ... //implementation } I don't really understand, what is the purpose of such macros? This library is for a real-time application and I suppose that using such macros must slow-down an application.

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• creating a table based on fields from three different tables

  - by ozlem

  Hi, I am using MS-Access 2003. I have three tables containing values of w,Q and L. In the Q table I have three fields: country_name, ISIC_code, and Q value. In the L table, there are three fields, country_name, ISIC_code, and L value. And in the w table there are two fields; country_name and w value. Country_names, and ISIC_code might be different for each table. What I want to do is create a new table with the values b(j)=w(i)L(ij)/Q(ij), where i is the country and j is the ISIC_code. So first I will check if the country name and ISIC_code are the same in L and Q tables. If they are equal I will calculate L/Q and then multiply this with w value of the same country if it exists. I appreciate any help.

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• How to retrieve large data from oracle database using vbscript

  - by allenzzzxd

  Hi guys, I'm now working on vbscript to do some test. Actuelly, I want to retrieve a large amount of data from an oracle database, so I write the code like this: sql = "Select * from CORE_DB where MC = '" & mstr & "' " Set myrs = db_execute_query(curConnection, sql) Then I count the rows in myrs,there are 248 rows. So then I do a For loop to retrieve some fields of each row. For k = 0 To db_get_rows_count(myrs) But then I found that the content of the row k when k 133 was always equal to k = 133. So this makes an error. As I think, there may be a limit size of mrys ? Could anyone light me about this? Thanks a lot in advance

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• Direct3D Rotation Matrix from Vector and vice-versa

  - by Beta Carotin

  I need to compute a rotation matrix from a direction vector, and a direction vector from a rotation matrix. The up direction should correspond to the z-axis, forward is y and right is x; D3DXMATRIX m; // the rotation matrix D3DXVECTOR3 v; // this is the direction vector wich is given D3DXVECTOR3 r; // resulting direction vector float len = D3DXVec3Length(&v); // length of the initial direction vector // compute matrix D3DXMatrixLookAtLH(&m, &v, &D3DXVECTOR3(0,0,0), &D3DXVECTOR3(0,0,1)); // use the matrix on a vector { 0, len, 0 } D3DXVec3TransformCoord(&r, &D3DXVECTOR3(0,len,0), &m); Now, the vector r should be equal to v, but it isnt. What exactly do I have to do to get the results I need?

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• VBA for filtering columns

  - by Ampi Severe

  I have a big database-like sheet, first row contains headers. I would like a subset of rows of this table based on column values. Two issues: 1) VBA-wise I would like to loop through the columns, when the values for all necessary columns all match, copy the entire row into a new sheet. 2) The subset of rows is based on a list. This should be the first column to be looped through. For example I want all rows where the value in column A is equal to one of the values in my list. Is there any possibility to autofilter strings based on a list (column) of strings? EDIT Thanks to @Doug Glancy the autofiltering works now, so I've removed my (horrible) code and issue 1 is solved.

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• How to check if string contains a string in string array

  - by Abu Hamzah

  edit: the order might change as you can see in the below example, both string have same name but different order.... How would you go after checking to see if the both string array match? the below code returns true but in a reality its should return false since I have extra string array in the _check what i am trying to achieve is to check to see if both string array have same number of strings. string _exists = "Adults,Men,Women,Boys"; string _check = "Men,Women,Boys,Adults,fail"; if (_exists.All(s => _check.Contains(s))) //tried Equal { return true; } else { return false; }

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• WPF/XAML - compare the "SelectedIndex" of two comboboxes (DataTrigger?)

  - by Luaca

  hello, i've got two comboboxes with the same content. the user should not be allowed to choose the same item twice. therefore the comboboxes' contents (= selectedindex?) should never be equal. my first attempt was to comapare the selectedindex with a datatrigger to show/hide a button: <DataTrigger Binding="{Binding ElementName=comboBox1, Path=SelectedIndex}" Value="{Binding ElementName=comboBox2, Path=SelectedIndex}"> <Setter Property="Visibility" Value="Hidden" /> </DataTrigger> it seems that it is not possible to use Value={Binding}. is there any other way (if possible without using a converter)? thanks in advance!

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• Best way to validate currency input?

  - by Abe Miessler

  I have created the TextBox and CompareValidator below which I thought would allow input in the following forms: 5 5.00 $5.00 Unfortunately it's not allowing the version with the dollar sign in it. What is the point of doing a type check against currency if you don't allow the dollar sign? Is there a way to allow this symbol? <asp:TextBox ID="tb_CostShare" runat="server" Text='<%# Eval("CostShare", "{0:$0.00}")%>' CausesValidation="true" /> <asp:CompareValidator ID="vld_CostShare" runat="server" ControlToValidate="tb_CostShare" Operator="DataTypeCheck" Type="Currency" ValidationGroup="vld" ErrorMessage="You must enter a dollar amount for 'Cost Share'." />

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• How to create and Expression tree to do the same as "StartsWith"

  - by Jonathan

  Hi to all. Currently, I have this method to compare two numbers Private Function ETForGreaterThan(ByVal query As IQueryable(Of T), ByVal propertyValue As Object, ByVal propertyInfo As PropertyInfo) As IQueryable(Of T) Dim e As ParameterExpression = Expression.Parameter(GetType(T), "e") Dim m As MemberExpression = Expression.MakeMemberAccess(e, propertyInfo) Dim c As ConstantExpression = Expression.Constant(propertyValue, propertyValue.GetType()) Dim b As BinaryExpression = Expression.GreaterThan(m, c) Dim lambda As Expression(Of Func(Of T, Boolean)) = Expression.Lambda(Of Func(Of T, Boolean))(b, e) Return query.Where(lambda) End Function It works fine and is consumed in this way query = ETForGreaterThan(query, Value, propertyInfo) As you can see, I give it an IQueryable collection and it add a where clause to it, base on a property and a value. Y can construct Lessthan, LessOrEqualThan etc equivalents as Expression has this operators predefined. ¿How can I transform this code to do the same with strings? Expression don't give me a predefined operator like "contains" or "startwith" and I'm really noob with Expression trees. Thanks, and please Post your answer in C#/VB. Choose the one that make you feel more confortable.

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• C++ and preprocessor macro gotcha

  - by aaa

  hello. Appologies for yet another gotcha question. Can you figure out what is wrong with the statement below? gcc error states: "type name declared as function returning array". #define MACRO(a) (a)[1] class index { typedef int index_type[2]; index_type& operator[](int i); }; int k = 0; int i = MACRO(index()[k]); ps: is such questions are deemed too annoying, I am going to stop.

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• Is call to function object inlined?

  - by dehmann

  In the following code, Foo::add calls a function via a function object: struct Plus { inline int operator()(int x, int y) const { return x + y; } }; template<class Fct> struct Foo { Fct fct; Foo(Fct f) : fct(f) {} inline int add(int x, int y) { return fct(x,y); // same efficiency adding directly? } }; Is this the same efficiency as calling x+y directly in Foo::add? In other words, does the compiler typically directly replace fct(x,y) with the actual call, inlining the code, when compiling with optimizations enabled?

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• What is the best solution to replace a new memory allocator in an existing code?

  - by O. Askari

  During the last few days I've gained some information about memory allocators other than the standard malloc(). There are some implementations that seem to be much better than malloc() for applications with many threads. For example it seems that tcmalloc and ptmalloc have better performance. I have a C++ application that uses both malloc and new operators in many places. I thought replacing them with something like ptmalloc may improve its performance. But I wonder how does the new operator act when used in C++ application that runs on Linux? Does it use the standard behavior of malloc or something else? What is the best way to replace the new memory allocator with the old one in the code? Is there any way to override the behavior or new and malloc or do I need to replace all the calls to them one by one?

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• Twitter oauth php problems

  - by Patrick Gates

  I'm writing some backend script for a twitter app and heres how it's going On the app you click a button that sends you to login.php on my server which logs into my database connects to twitter with my consumer key and secret: $to = new TwitterOAuth($consumer_key, $consumer_secret); $tok = $to->getRequestToken(); $request_link = $to->getAuthorizeURL($tok); and then writes the token and secret to the database, sets a session equal to the id in the database of the token and secret and then redirects to the "$request_link" You then go through the process of logging in and such on twitter and it redirects you to callback.php on my server Callback.php consists of logging into the database again, getting the new token and secret, and then writing the new token and secret to the database and then prompts you to go back to the app Then on the app, all I'm trying to do is access the basic credentials$to->get('account/verify_credentials') and it keeps coming back "could not authenticate you" What am I doing wrong?? Thank you for all the help :)

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