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  • Turing Machine & Modern Computer

    - by smwikipedia
    I heard a lot that modern computers are based on Turing machine. I'd like to share my understanding and hear your comments. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine. The above is my naive understanding about the working paradigm of modern computer. I couln't wait to hear your comments. Thanks very much.

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  • Cannot modify header information - headers already sent by

    - by bhaskaragr29
    <?php //require_once 'wordwrap.php'; //$text="Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum Lorem Ipsum"; $im=imagecreatefrompng('testing.png'); //$arr=word($text); $white = imagecolorallocate($im,255,255,255); $font='arial.ttf'; $m=121; for($i=0;$i<sizeof($arr);$i++) { imagettftext($im,25,11,124,'Hello world!', $white); } header('Content-type: image/png'); imagepng($im); imagedestroy($im); ?> I am getting error..please help me on this.

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  • Access modifiers in Object-Oriented Programming

    - by Imran
    I don't understand Access Modifiers in OOP. Why do we make for example in Java instance variables private and then use public getter and setter methods to access them? I mean what's the reasoning/logic behind this? You still get to the instance variable but why use setter and getter methods when you can just make your variables public? please excuse my ignorance as I am simply trying to understand why? Thank you in advance. ;-)

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  • Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

    - by Thor Thurn
    I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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  • Dynamic programming solution to the subset-sum decision problem

    - by Gail
    How can a dynamic programming solution for the unbounded knapsack decision problem be used to come up with a dynamic programming solution to the subset-sum decision problem? This limitation seems to render the unbounded knapsack problem useless. In the unbounded knapsack, we simply store true or false for if some subset of integers sum up to our target value. However, if we have a limit on the frequency of the use of these integers, the optimal substructure at least appears to fail. How can this be done?

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  • VB.net Regex Get Information

    - by xzerox
    Well I am currently trying to get the word/text in between these 2 things : and ! I tried this Dim nick As String = String.Empty Dim p = ":(?<ircnick>.*?)!" Dim Matches = Regex.Matches(mail, p, RegexOptions.IgnoreCase Or RegexOptions.Singleline) If Matches IsNot Nothing AndAlso Matches.Count > 0 Then For Each Match As Match In Matches If Match.Groups("info").Success Then nick = (Match.Groups("ircnick").Value) End If Next End If It doesn't display anything. If you guys can fix this code for me I would be happy :D.

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  • How to share information across controllers?

    - by Steffen
    Hi everybody, I recently started programming my first Cocoa app. I have ran into a problem i hope you can help me with. I have a MainController who controls the user browsing his computer and sets some textfield = the chosen folder. I need to retrieve that chosen folder in my AnalyzeController in order to do some work. How do i pass the textfield objectValue from the MainController to the AnalyzeController? Thanks

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  • Which operating systems book should I go for?

    - by pecker
    Hi, I'm in a confusion. For our course (1 year ago) I used Stallings. I read it. It was fine. But I don't own any operating system's book. I want to buy a book on operating systems. I'm confused!! which one to pick? Modern Operating Systems (3rd Edition) ~ Andrew S. Tanenbaum (Author) Operating System Concepts ~ Abraham Silberschatz , Peter B. Galvin, Greg Gagne Operating Systems: Internals and Design Principles (6th Edition) ~ William Stallings I've plans of getting into development of realworld operating systems : Linux, Unix & Windows Driver Development. I know that for each of these there are specific books available. But I feel one should have a basic book on the shelf. So, which one to go for?

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  • Context-sensitive grammar for specific language

    - by superagio
    How can I construct a grammar that generates this language? Construct a grammar that generates L: L = {a^n b^m c^k|k>n, k>m} I believe my productions should go along this lines: S-> ABCC A-> a|aBC|BC B-> b|bBC C-> c|Cc CB->BC The idea is to start with 2 c and keep always one more c, and then with C-c|Cc ad as much c as i want. How can my production for C remember the numbers of m and n.

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  • Proving that the distance values extracted in Dijkstra's algorithm is non-decreasing?

    - by Gail
    I'm reviewing my old algorithms notes and have come across this proof. It was from an assignment I had and I got it correct, but I feel that the proof certainly lacks. The question is to prove that the distance values taken from the priority queue in Dijkstra's algorithm is a non-decreasing sequence. My proof goes as follows: Proof by contradiction. Fist, assume that we pull a vertex from Q with d-value 'i'. Next time, we pull a vertex with d-value 'j'. When we pulled i, we have finalised our d-value and computed the shortest-path from the start vertex, s, to i. Since we have positive edge weights, it is impossible for our d-values to shrink as we add vertices to our path. If after pulling i from Q, we pull j with a smaller d-value, we may not have a shortest path to i, since we may be able to reach i through j. However, we have already computed the shortest path to i. We did not check a possible path. We no longer have a guaranteed path. Contradiction.

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  • Generating All Permutations of Character Combinations when # of arrays and length of each array are

    - by Jay
    Hi everyone, I'm not sure how to ask my question in a succinct way, so I'll start with examples and expand from there. I am working with VBA, but I think this problem is non language specific and would only require a bright mind that can provide a pseudo code framework. Thanks in advance for the help! Example: I have 3 Character Arrays Like So: Arr_1 = [X,Y,Z] Arr_2 = [A,B] Arr_3 = [1,2,3,4] I would like to generate ALL possible permutations of the character arrays like so: XA1 XA2 XA3 XA4 XB1 XB2 XB3 XB4 YA1 YA2 . . . ZB3 ZB4 This can be easily solved using 3 while loops or for loops. My question is how do I solve for this if the # of arrays is unknown and the length of each array is unknown? So as an example with 4 character arrays: Arr_1 = [X,Y,Z] Arr_2 = [A,B] Arr_3 = [1,2,3,4] Arr_4 = [a,b] I would need to generate: XA1a XA1b XA2a XA2b XA3a XA3b XA4a XA4b . . . ZB4a ZB4b So the Generalized Example would be: Arr_1 = [...] Arr_2 = [...] Arr_3 = [...] . . . Arr_x = [...] Is there a way to structure a function that will generate an unknown number of loops and loop through the length of each array to generate the permutations? Or maybe there's a better way to think about the problem? Thanks Everyone!

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  • initializing structs using user-input information

    - by johnny boy
    I am trying to make a program that works with poker (texas holdem) starting hands; each hand has a value from 1 to 169, and i want to be able to input each card and whether they are suited or not, and have those values correspond to a series of structs. Here is the code so far, i cant seem to get it to work (im a beginning programmer). oh and im using visual studio 2005 by the way #include "stdafx.h" #include <iostream> int main() { using namespace std; struct FirstCard { struct SecondCard { int s; //suited int n; //non-suited }; SecondCard s14; SecondCard s13; SecondCard s12; SecondCard s11; SecondCard s10; SecondCard s9; SecondCard s8; SecondCard s7; SecondCard s6; SecondCard s5; SecondCard s4; SecondCard s3; SecondCard s2; }; FirstCard s14; //ace FirstCard s13; //king FirstCard s12; //queen FirstCard s11; //jack FirstCard s10; FirstCard s9; FirstCard s8; FirstCard s7; FirstCard s6; FirstCard s5; FirstCard s4; FirstCard s3; FirstCard s2; s14.s14.n = 169; // these are the values that each combination s13.s13.n = 168; // will evaluate to, would eventually have s12.s12.n = 167; // hand combinations all the way down to 1 s11.s11.n = 166; s14.s13.s = 165; s14.s13.s = 164; s10.s10.n = 163; //10, 10, nonsuited s14.s13.n = 162; s14.s11.s = 161; s13.s12.s = 160;// king, queen, suited s9.s9.n = 159; s14.s10.s = 158; s14.s12.n = 157; s13.s11.s = 156; s8.s8.n = 155; s12.s11.s = 154; s13.s10.s = 153; s14.s9.s = 152; s14.s11.n = 151; cout << "enter first card: " << endl; cin >> somthing?//no idea what to put here, but this would somehow //read out the user input (a number from 2 to 14) //and assign it to the corresponding struct cout << firstcard.secondcard.suited_or_not << endl; //this would change depending //on what the user inputs system("Pause"); }

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  • Finding the nth number of primes

    - by Braxton Smith
    I can not figure out why this won't work. Please help me from math import sqrt pN = 0 numPrimes = 0 num = 1 def checkPrime(x): '''Check\'s whether a number is a prime or not''' prime = True if(x==2): prime = True elif(x%2==0): prime=False else: root=int(sqrt(x)) for i in range(3,root,2): if(x%i==0): prime=False break return prime n = int(input("Find n number of primes. N being:")) while( numPrimes != n ): if( checkPrime( num ) == True ): numPrimes += 1 pN = num print("{0}: {1}".format(numPrimes,pN)) num += 1 print("Prime {0} is: {1}".format(n,pN))

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  • asp.net mvc making delete usercontrol information passing on and off

    - by mazhar kaunain baig
    i am creating a generalize deleteusercontrol , my aim is that on the listing page where all the records are listed when the delete is pressed i want to display the acknowledgment on the same page up the list. I had little idea to do that q1) first of all where will i place my deleteusercontrol(in the shared folder?). q2) on and off the deleteusercontrol as the acknowledgment will not be there all the time how would i be doing that on delete press. i don't want to pass any data in the querystring. q3)how would i be passing the records list id and listname to the general deleteusercontrol as it would be same for all the listing

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  • Examples of monoids/semigroups in programming

    - by jkff
    It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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  • How to scan an array for certain information

    - by Andrew Martin
    I've been doing an MSc Software Development conversion course, the main language of which is Java, since the end of September. We have our first assessed practical coming and I was hoping for some guidance. We have to create an array that will store 100 integers (all of which are between 1 and 10), which are generated by a random number generator, and then print out ten numbers of this array per line. For the second part, we need to scan these integers, count up how often each number appears and store the results in a second array. I've done the first bit okay, but I'm confused about how to do the second. I have been looking through the scanner class to see if it has any methods which I could use, but I don't see any. Could anyone point me in the right direction - not the answer, but perhaps which library it comes from? Code so far: import java.util.Random; public class Practical4_Assessed { public static void main(String[] args) { Random numberGenerator = new Random (); int[] arrayOfGenerator = new int[100]; for (int countOfGenerator = 0; countOfGenerator < 100; countOfGenerator++) arrayOfGenerator[countOfGenerator] = numberGenerator.nextInt(10); int countOfNumbersOnLine = 0; for (int countOfOutput = 0; countOfOutput < 100; countOfOutput++) { if (countOfNumbersOnLine == 10) { System.out.println(""); countOfNumbersOnLine = 0; countOfOutput--; } else { System.out.print(arrayOfGenerator[countOfOutput] + " "); countOfNumbersOnLine++; } } } } Thanks, Andrew

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  • Can I read AssemblyFile information in Inno Setup

    - by Nifle
    I would like to read these three values from my application.exe in my Inno Setup script. [assembly: AssemblyCompany("My Company")] [assembly: AssemblyProduct("My Great Application")] [assembly: AssemblyFileVersion("9.3.2")] Does anyone know how this might be accomplished? I know I can get the last one using GetFileVersion("path/to/greatapp.exe") is there something similar for the first two?

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  • Cropping image with ImageScience

    - by fl00r
    ImageScience is cool and light. I am using it in my sinatra app. But I can't understand how can I crop image with not square form and how can I make thumbnail with two dimensions. As I found on ImageScience site: ImageScience.with_image(file) do |img| img.cropped_thumbnail(100) do |thumb| thumb.save "#{file}_cropped.png" end img.thumbnail(100) do |thumb| thumb.save "#{file}_thumb.png" end img.resize(100, 150) do |img2| img2.save "#{file}_resize.png" end end I can crop thumb and resize thumb only with ONE dimension but I want to use two, as in RMagick. For example I want to crop 100x200px box from image, or I want to make thumbnail with width or height not bigger then 300 (width) or 500 (height) pixels.

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  • Proper way to store user information

    - by Darthg8r
    The standard Joomla registration forms has a limited set of fields available. What's the "correct" method for adding the user's first name, last name, and phone number to the registration project? I can certainly modify the Joomla core, but that's less than ideal. A nickel for your thoughts.

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  • Best way to store sales tax information

    - by Seph
    When designing a stock management database system (sales / purchases) what would be the best way to store the various taxes and other such amounts? A few of the fields that could be saved are: Unit price excluding tax Unit price including tax Tax per item Total excluding tax (rounded to 2 decimals) Total including tax (rounded to 2 decimals) Total tax (rounded to 2 decimals) Currently the most reasonable solution so far is storing down (roughly) item, quantity, total excluding tax (rounded) and the total tax (rounded). Can anyone suggest some better way of storing this details for a generic system? Also, given the system needs to be robust, what should be done if there were multiple tax values (eg: state and city) which might need to be separated, in this case a separate table would be in order, but would it be considered excessive to just have a rowID and some taxID mapping to a totalTax column?

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