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  • How to bind to another event after ajax call in jquery

    - by robert
    Hi, I'm creating a graph using flot javascript library. I have enabled clickable event and the div is binded to plotclick event. So, when a datapoint is clicked, an ajax call is made and the result is used to replace the current div. After this i need to bind the div to a new event. I tried to call bind, but it is still bound to old callback. When i call unbind and bind, the new callback is not called. var handleTeacherClick = function( event, pos, item ) { if( typeof item != "undefined" && item ) { var user_id = jQuery( 'input[name="id' + item.datapoint[0] + '"]' ).val(); jQuery.ajax({ type: 'POST', url: BASEPATH + 'index.php/ajax/home/latest', data: { "user_id": user_id }, dataType: 'json', success: function ( result ) { jQuery.plot(jQuery('#stats_prog'), result.progress_data, result.progress_options); jQuery.plot(jQuery('#stats_perf'), result.performance_data, result.performance_options); jQuery('.stats_title'). html('<span class="stats_title">'+ ' >> Chapter '+Math.ceil(item.datapoint[0])+'</span>'); jQuery('#stats_prog')./*unbind("plotclick").*/ bind('plotclick', statClickHandler ); jQuery('#stats_perf')./*unbind("plotclick"). */ bind( 'plotclick', statClickHandler ); }, }); } }

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  • Dynamic loading of shared objects using dlopen()

    - by Andy
    Hi, I'm working on a plain X11 app. By default, my app only requires libX11.so and the standard gcc C and math libs. My app has also support for extensions like Xfixes and Xrender and the ALSA sound system. But this feature shall be made optional, i.e. if Xfixes/Xrender/ALSA is installed on the host system, my app will offer extended functionality. If Xfixes or Xrender or ALSA is not there, my app will still run but some functionality will not be available. To achieve this behaviour, I'm not linking dynamically against -lXfixes, -lXrender and -lasound. Instead, I'm opening these libraries manually using dlopen(). By doing it this way, I can be sure that my app won't fail in case one of these optional components is not present. Now to my question: What library names should I use when calling dlopen()? I've seen that these differ from distro to distro. For example, on openSUSE 11, they're named the following: libXfixes.so libXrender.so libasound.so On Ubuntu, however, the names have a version number attached, like this: libXfixes.so.3 libXrender.so.1 libasound.so.2 So trying to open "libXfixes.so" would fail on Ubuntu, although the lib is obviously there. It just has a version number attached. So how should my app handle this? Should I let my app scan /usr/lib/ first manually to see which libs we have and then choose an appropriate one? Or does anyone have a better idea? Thanks guys, Andy

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  • Translation of a RoR view to Java

    - by mnml
    Hi, for some reasons I am trying to translate the following RoR view code to a GSP view: List<Object> objectscontains the data I want to display in 3 columns <% modulo_objects = @objects.length % 3 base = @objects.length / 3 base = base.ceil case modulo_objects when 0 cols = [base, base, base] when 1 cols = [base, base + 1, base] when 2 cols = [base + 1, base, base + 1] end counter = 0 %> <% 3.times do |i| %> <td width="220" align="center" style="padding-right: 15px;"> <% cols[i].times do %> <h1><a href="/objects/show/<%= @objects[counter].urlname %>" ><%= @objects[counter].name %></a></h1> <% counter = counter + 1 %> <% end %> </td> <% end %> This is what I got so far: #{extends 'main.html' /} %{ modulo_objects = objects.size() % 3 base = objects.size() / 3 base = Math.ceil(base) if(modulo_objects == 0) cols = [base, base, base] else if(modulo_objects == 1) cols = [base, base + 1, base] else if(modulo_objects == 2) cols = [base + 1, base, base + 1] endif counter = 0 }% #{list items:1..3, as:'i'} <td width="220" align="center" style="padding-right: 15px;"> #{list items:cols[i]} <a href="@{Objects.show(objects.get(counter).name.replaceAll(" ", "-"))}" >${objects.get(counter).name}</a> %{ counter = counter + 1 }% #{/list} </td> #{/list} The idea is to keep the items organised in 3 columns like 1|0|1 4|5|4 or 5|4|5 for example, I don't really understand if #{list items:cols[i]} will reproduce ruby's cols[i].times do. So far the Java view is does not display more than two elements.

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  • jquery.append() - only the last element of my list is appended, previous ones are erased

    - by jaes
    Hi, I have a page like this : <div id="daysTable"> <div id="day0" class="day"></div> <div id="day1" class="day"></div> <div id="day2" class="day"></div> <div id="day3" class="day"></div> <div id="day4" class="day"></div> <div id="day5" class="day"></div> <div id="day6" class="day"></div> </div> and some javascript to fill my calendar like this function getWeek(){ $.getJSON("/getWeek",function(events){ var eventHeight = $("#hoursTable > div").height(); var eventWidth = $("#daysTable > div").width(); var startWeek = events[0]// timestamp of the start of the week for(var i = 1; i < events.length; i ++){ $(".day").empty(); var startHour = (events[i].startDate - startWeek)/3600 var duration = (events[i].stopDate - startWeek)/3600 - startHour var dayStart = Math.floor(startHour/24); var startHour = startHour - dayStart * 24 divEvent = $('<div id="event'+events[i].idEvent+'"/>') .width(eventWidth-2) .height(duration*eventHeight) .css("border","1px solid black") .css("margin-top",startHour*eventHeight) .html(events[i].name); divEvent.appendTo("#day"+dayStart); console.log(divEvent); } }); } my problem being : events contain 3 element I'd like to display but only the last is displayed. If I stop my "for" at the first iteration I can see the first div appended, but it seems that if my loop goes for three iteration the two previous are deleted. The console.log() display some "not-anymore" existing element. Any idea ?

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  • Project Euler, Problem 10 java solution not working

    - by Dennis S
    Hi, I'm trying to find the sum of the prime numbers < 2'000'000. This is my solution in java but I can't seem get the correct answer. Please give some input on what could be wrong and general advice on the code is appreciated. Printing 'sum' gives: 1308111344, which is incorrect. /* The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below two million. */ class Helper{ public void run(){ Integer sum = 0; for(int i = 2; i < 2000000; i++){ if(isPrime(i)) sum += i; } System.out.println(sum); } private boolean isPrime(int nr){ if(nr == 2) return true; else if(nr == 1) return false; if(nr % 2 == 0) return false; for(int i = 3; i < Math.sqrt(nr); i += 2){ if(nr % i == 0) return false; } return true; } } class Problem{ public static void main(String[] args){ Helper p = new Helper(); p.run(); } }

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  • Problems sorting by date

    - by Nathan
    I'm attempting to only display data added to my database 24 hours ago or less. However, for some reason, the code I've written isn't working, and both entries in my database, one from 1 hour ago, one from 2 days ago, show up. Is there something wrong with my equation? Thanks! public void UpdateValues() { double TotalCost = 0; double TotalEarned = 0; double TotalProfit = 0; double TotalHST = 0; for (int i = 0; i <= Program.TransactionList.Count - 1; i++) { DateTime Today = DateTime.Now; DateTime Jan2013 = DateTime.Parse("01-01-2013"); //Hours since Jan12013 int TodayHoursSince2013 = Convert.ToInt32(Math.Round(Today.Subtract(Jan2013).TotalHours)); //7 int ItemHoursSince2013 = Program.TransactionList[i].HoursSince2013; //Equals 7176, and 7130 if (ItemHoursSince2013 - TodayHoursSince2013 <= 24) { TotalCost += Program.TransactionList[i].TotalCost; TotalEarned += Program.TransactionList[i].TotalEarned; TotalProfit += Program.TransactionList[i].TotalEarned - Program.TransactionList[i].TotalCost; TotalHST += Program.TransactionList[i].TotalHST; } } label6.Text = "$" + String.Format("{0:0.00}", TotalCost); label7.Text = "$" + String.Format("{0:0.00}", TotalEarned); label8.Text = "$" + String.Format("{0:0.00}", TotalProfit); label10.Text = "$" + String.Format("{0:0.00}", TotalHST); }

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  • Do variable references (alias) incure runtime costs in c++?

    - by cheshirekow
    Maybe this is a compiler specific thing. If so, how about for gcc (g++)? If you use a variable reference/alias like this: int x = 5; int& y = x; y += 10; Does it actually require more cycles than if we didn't use the reference. int x = 5; x += 10; In other words, does the machine code change, or does the "alias" happen only at the compiler level? This may seem like a dumb question, but I am curious. Especially in the case where maybe it would be convenient to temporarily rename some member variables just so that the math code is a little easier to read. Sure, we're not exactly talking about a bottleneck here... but it's something that I'm doing and so I'm just wondering if there is any 'actual' difference... or if it's only cosmetic.

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  • What makes deployment successful for some users and unsuccessful for others?

    - by Julien
    I am trying to deploy a Visual C++ application (developed with Microsoft Visual Studio 2008) using a Setup and Deployment Project. After installation, users on some target computers get the following error message after launching the application executable: “This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix the problem.” Another user after installation could run the application properly. I cannot find the root cause of this problem, despite spending several hours on the Visual Studio help files and online forums (most postings date back to 2006). Does anyone at Stack Overflow have a suggestion? Thanks in advance. Additional details appear below. The application uses FLTK 1.1.9 for a GUI library, as well as some Boost 1.39 libraries (regex, lexical_cast, date_time, math). I made sure I am trying to deploy the release version (not the debug version) of the application. The Runtime library in the Code Generation settings is Multi-threaded DLL (/MD). The dependency walker of myapp.exe lists the following DLLs: wsock32.dll, comctl32.dll, kernel32.dll, user32.dll, gdi32.dll, shell32.dll, ole32.dll, mvcp90.dll, msvcr90.dll. In the Setup and Deployment Project, I add the following DLLs to the File System on Target Machine: fltkdlld.dll, and a folder named Microsoft.VC90.CRT with msvcm90.dll, msvcp90.dll, mcvcr90.dll and Microsoft.VC90.CRT.manifest. The installation process on the target computers getting the error message requires having the .Net Framework 3.5 installed first. Any suggestion? Thanks in advance!

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  • incremental way of counting quantiles for large set of data

    - by Gacek
    I need to count the quantiles for a large set of data. Let's assume we can get the data only through some portions (i.e. one row of a large matrix). To count the Q3 quantile one need to get all the portions of the data and store it somewhere, then sort it and count the quantile: List<double> allData = new List<double>(); foreach(var row in matrix) // this is only example. In fact the portions of data are not rows of some matrix { allData.AddRange(row); } allData.Sort(); double p = 0.75*allData.Count; int idQ3 = (int)Math.Ceiling(p) - 1; double Q3 = allData[idQ3]; Now, I would like to find a way of counting this without storing the data in some separate variable. The best solution would be to count some parameters od mid-results for first row and then adjust it step by step for next rows. Note: These datasets are really big (ca 5000 elements in each row) The Q3 can be estimated, it doesn't have to be an exact value. I call the portions of data "rows", but they can have different leghts! Usually it varies not so much (+/- few hundred samples) but it varies! This question is similar to this one: http://stackoverflow.com/questions/1058813/on-line-iterator-algorithms-for-estimating-statistical-median-mode-skewness But I need to count quantiles. ALso there are few articles in this topic, i.e.: http://web.cs.wpi.edu/~hofri/medsel.pdf http://portal.acm.org/citation.cfm?id=347195&dl But before I would try to implement these, I wanted to ask you if there are maybe any other, qucker ways of counting the 0.25/0.75 quantiles?

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  • algorithim for simple colision detection in Java

    - by Bob Twinkles
    I'm not very experienced with Java, just started a couple weeks ago, but I have a simple applet that has two user controlled balls, drawn through java.awt and I need a way to detect a collision with between them. I have an algorithm for detecting collision with the walls: while (true){ if (xPositon > (300 - radius)){ xSpeed = -xSpeed; } else if (xPositon < radius){ xSpeed = -xSpeed; } else if (yPositon > (300 - radius)) { ySpeed = -ySpeed; } else if (yPositon < radius){ ySpeed = -ySpeed; } xPositon += xSpeed; yPositon += ySpeed; and for the second ball if (xPositon2 > (300 - radius)){ xSpeed2 = -xSpeed2; } else if (xPositon2 < radius){ xSpeed2 = -xSpeed2; } else if (yPositon2 > (300 - radius)) { ySpeed2 = -ySpeed2; } else if (yPositon2 < radius){ ySpeed2 = -ySpeed2; } xPositon2 += xSpeed2; yPositon2 += ySpeed2; the applet is 300 pixels by 300 pixels radius stores the radius of the circles xPositon and xPositon2 store the x cordanents for the two balls yPositon and yPositon store the y cordanents for the two balls xSpeed and xSpeed2 store the x velocities for the two balls ySpeed and ySpeed2 store the y velocities for the two balls I've only taken algebra 1 so please no advanced math or physics.

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  • Normals per index?

    - by WarrenFaith
    I have a pyramid which has 5 vertex and 18 indices. As I want to add normals to each face I just found solution for normals for each vertex. That means I can't use indices to define my pyramid I need to have 18 vertex (and 3 times the same vertex for the same point in space). There must be a solution to use normals not on vertex base but on index base. Some code (javascript): var vertices = [ -half, -half, half, // 0 front left half, -half, half, // 1 front right half, -half, -half, // 2 back right -half, -half, -half, // 3 back left 0.0, Math.sqrt((size * size) - (2 * (half * half))) - half, 0.0 // 4 top ]; var vertexNormals = [ // front face normaleFront[0], normaleFront[1], normaleFront[2], normaleFront[0], normaleFront[1], normaleFront[2], normaleFront[0], normaleFront[1], normaleFront[2], // back face normaleBack[0], normaleBack[1], normaleBack[2], normaleBack[0], normaleBack[1], normaleBack[2], normaleBack[0], normaleBack[1], normaleBack[2], // left face normaleLeft[0], normaleLeft[1], normaleLeft[2], normaleLeft[0], normaleLeft[1], normaleLeft[2], normaleLeft[0], normaleLeft[1], normaleLeft[2], // right face normaleRight[0], normaleRight[1], normaleRight[2], normaleRight[0], normaleRight[1], normaleRight[2], normaleRight[0], normaleRight[1], normaleRight[2], // bottom face 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, 0.0, -1.0, 0.0, ]; var pyramidVertexIndices = [ 0, 1, 4, // Front face 2, 3, 4, // Back face 3, 0, 4, // Left face 1, 2, 4, // Right face 0, 1, 2, 2, 3, 0, // Bottom face ];

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  • why is a minus sign prepended to my biginteger?

    - by kyrogue
    package ewa; import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.logging.Level; import java.util.logging.Logger; import java.math.BigInteger; /** * * @author Lotus */ public class md5Hash { public static void main(String[] args) throws NoSuchAlgorithmException { String test = "abc"; MessageDigest md = MessageDigest.getInstance("MD5"); try { md.update(test.getBytes("UTF-8")); byte[] result = md.digest(); BigInteger bi = new BigInteger(result); String hex = bi.toString(16); System.out.println("Pringting result"); System.out.println(hex); } catch (UnsupportedEncodingException ex) { Logger.getLogger(md5Hash.class.getName()).log(Level.SEVERE, null, ex); } } } i am testing conversion of byte to hex and when done, the end result has a minus sign on the beginning of the string, why does this happen? i have read the docs and it says it will add a minus sign, however i do not understand it. And will the minus sign affect the hash result? because i am going to implement it to hash password stored on my database

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  • gluLookAt vectors and FPS-style camera

    - by Kevin Pamplona
    I am attempting to implemented an FPS-style camera by updating three vectors: EYE, DIR, UP. These vectors are the same that are used by gluLookAt (since gluLookAt is specified by the position of the camera, the direction it is looking at, and an up vector). I have already implemented the left-right and up-down strafing movements, but I'm having a lot of trouble understanding the math behind making the camera look-around while remaining stationary. In this case, the EYE vector remains the same, while I must update DIR and UP. Below is the code I tried, but it doesn't seem to work properly. Any suggestions? Thanks. void Transform::left(float degrees, vec3& dir, vec3& up) { vec3 axis; axis = glm::normalize(up); mat3 R = rotate(-degrees, axis); dir = R*dir; dir = R*up; }; void Transform::up(float degrees, vec3& dir, vec3& up) { vec3 axis; axis=glm::normalize(glm::cross(dir,up)); mat3 R = rotate(-degrees, axis); dir = R*dir-; up = R*up; };

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  • C ] How can I handle weird errors from calculating acos / sin / atan2?

    - by Phrixus
    Has anyone seen this weird value while handling sin / cos/ tan / acos.. math stuff? ===THE WEIRD VALUE=== -1.#IND00 ===================== void inverse_pos(double x, double y, double& theta_one, double& theta_two) { // Assume that L1 = 350 and L2 = 250 double B = sqrt(x*x + y*y); double angle_beta = atan2(y, x); double angle_alpha = acos((L2*L2 - B*B - L1*L1) / (-2*B*L1)); theta_one = angle_beta + angle_alpha; theta_two = atan2((y-L1*sin(theta_one)), (x-L1*cos(theta_one))); } This is the code I was working on. In a particular condition - like when x & y are 10 & 10, this code stores -1.#IND00 into theta_one & theta_two. It doesn't look like either characters or numbers :( Without a doubt, atan2 / acos / stuff are the problems. But the problem is, try and catch doesn't work either cuz those double variables have successfully stored some values in them. Moreover, the following calculations never complain about it and never break the program! I'm thinking of forcing to use this value somehow and make the entire program crash... So that I can catch this error.. Except for that idea, I have no idea how I should check whether these theta_one and theta_two variables have stored this crazy values. Any good ideas? Thank you in advance..

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  • How can someone with no experience learn how to program?

    - by Mugatu
    A friend and I have been coming up with website ideas for a couple years, mostly just jotting them down whenever we come up with a good, useful idea when browsing the web. For the past 6 months we've hired a couple different programmers to make a couple of the sites for us, but have been disappointed with how it's gone. Been too slow and too many miscommunications for our liking. So like the saying goes if you want something done right do it yourself, we're going to do it ourselves. I know nothing about programming, I've never written a line of code in my life. I consider myself very good with math and about as logical as you can get, but I have zero real-life programming knowledge. The sites we want to make are all pretty 'Web 2.0'ish', meaning user-generated content, commenting on posts, pages that change on the fly, etc. So here are some of my questions for anyone who's been there before: Is there a language you'd recommend learning first? Something that is a good indicator how most other languages work? What web programming languages do you recommend learning first based on popularity both now and the future. I don't want to learn a language that's going to be outdated by the time I'm an expert at it. Any specific books you'd recommend? Any general advice you'd give to someone literally starting at square zero for coding who plans on being in it for the long haul?

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  • Reversible numerical calculations in Prolog

    - by user8472
    While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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  • SetInterval missing property in js class

    - by sebastian
    I wrote simple class in JS witch works, but i had problem when i try use setInterval with it. Ex. if i do something like that ball = new ball(5,10,0, '#canvas'); ball.draw(); ball.draw(); ball.draw(); ball.draw(); It works. But this: ball = new ball(5,10,0, '#canvas'); setInterval(ball.draw, 100); Not work. I get error that values are undefined. function ball (x,y,z,holdingEl) { this.r = 5; //zmienna przechowujaca promien pilki this.size = this.r *2; // zmienna przechowujaca rozmiar this.ballSpeed = 100; // predkosc pilki this.ballWeight = 0.45; // masa pilki this.maxFootContactTime = 0.2; // maksymalny czas kontaktu pilki z noga - stala this.ctx = jQuery(holdingEl)[0].getContext("2d"); // obiekt pilki this.intVal = 100 // predkosc odswiezania this.currentPos = { // wspolrzedne pozycji x: x, y: y, z: z } this.interactionPos = { // wspolrzedne pozycji ostatniej interakcji x: -1, y: -1, z: -1 } this.direct = { // kierunek w kazdej plaszczyznie x : 1, y : 0, z : 0 } this.draw = function (){ this.ctx.clearRect(0,0,1100,800); this.ctx.beginPath(); this.ctx.arc(this.currentPos.x, this.currentPos.y, this.r, 0, Math.PI*2, true); this.ctx.closePath(); this.ctx.fill(); } }

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  • calculate camera up vector after glulookat()?

    - by carrots
    I'm just starting out teaching myself openGL and now adding openAL to the mix. I have some planets scattered around in 3D space and when I touch the screen, I'm assigning a sound to a random planet and then slowly and smoothly flying the "camera" over to look at it and listen to it. The animation/tweening part is working perfectly, but the openAL piece isn't quiet right. I move the camera around by doing a tiny translate() and gluLookAt() for every frame to keep things smooth (tweening the camera position and lookAt coords). The trouble seems to be with the stereo image I'm getting out of the headphones.. it seems like the left/right/up/down is mixed up sometimes after the camera rolls or spins. I am pretty sure the trouble is here: ALfloat listenerPos[]={camera->currentX,camera->currentY,camera->currentZ}; ALfloat listenerOri[]={camera->currentLookX, camera->currentLookY, camera->currentLookZ, 0.0,//Camera Up X <--- here 0.1,//Camera Up Y <--- here 0.0}//Camera Up Z <--- and here alListenerfv(AL_POSITION,listenerPos); alListenerfv(AL_ORIENTATION,listenerOri); I'm thinking I need to recompute the UP vector for the camera after each gluLookAt() to straighten out the audio positioning problem.. but after hours of googling and experimenting I'm stuck in math that suddenly got way over my head. 1) Am I right that I need to recalculate the up vector after each gluLookAt() i do? 2) If so, can someone please walk me though figuring out how to do that?

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  • Shuffling words in a sentence in javascript (coding horror - How to improve?)

    - by Bill Zimmerman
    Hi, I'm trying to do something that is fairly simple, but my code looks terrible and I am certain there is a better way to do things in javascript. I am new to javascript, and am trying to improve my coding. This just feels very messy. All I want to do is to randomly change the order some words on a web page. In python, the code would look something like this: s = 'THis is a sentence' shuffledSentence = random.shuffle(s.split(' ')).join(' ') However, this is the monstrosity I've managed to produce in javascript //need custom sorting function because javascript doesn't have shuffle? function mySort(a,b) { return a.sortValue - b.sortValue; } function scrambleWords() { var content = $.trim($(this).contents().text()); splitContent = content.split(' '); //need to create a temporary array of objects to make sorting easier var tempArray = new Array(splitContent.length); for (var i = 0; i < splitContent.length; i++) { //create an object that can be assigned a random number for sorting var tmpObj = new Object(); tmpObj.sortValue = Math.random(); tmpObj.string = splitContent[i]; tempArray[i] = tmpObj; } tempArray.sort(mySort); //copy the strings back to the original array for (i = 0; i < splitContent.length; i++) { splitContent[i] = tempArray[i].string; } content = splitContent.join(' '); //the result $(this).text(content); } Can you help me to simplify things?

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  • Generate random number from an arbitrary weighted list

    - by Fernando
    Here's what I need to do, I'll be doing this both in PHP and JavaScript. I have a list of numbers that will range from 1 to 300-500 (I haven't set the limit yet). I will be running a drawing were 10 numbers will be picked at random from the given range. Here's the tricky part: I want some numbers to be less likely to be drawn up. A small set of those 300-500 will be flagged as "lucky numbers". For example, out of 100 drawings, most numbers have equal chances of being drawn, except for a few, that will only be picked once every 30-50 drawings. Basically I need to artificially set the probability of certain numbers to be picked while maintaining an even distribution with the rest of the numbers. The only similar thing I've found so far is this question: Generate A Weighted Random Number, the problem being that my spec has considerably more numbers (up to 500) so the weights would get very small and supposedly this could be a problem with that solution (Rejection Sampling). I'm still trying it, though, but I wonder if there other solutions. Math is not my thing so I appreciate any input. Thanks.

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  • Referencing not-yet-defined variables - Java

    - by user2537337
    Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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  • How Would a Newborn Baby Learn Web Programming?

    - by Mugatu
    Hello all, I chose that title because I equate my knowledge of web programming and web development with that of a newborn. Here's the shortest version of my story and what I'm looking to do: A friend and I have been coming up with website ideas for a couple years, mostly just jotting them down whenever we come up with a good, useful idea when browsing the web. For the past 6 months we've hired a couple different programmers to make a couple of the sites for us, but have been disappointed with how it's gone. Been too slow and too many miscommunications for our liking. So like the saying goes if you want something done right do it yourself, we're going to do it ourselves. I know nothing about programming, I've never written a line of code in my life. I consider myself very good with math and about as logical as you can get, but I have zero real-life programming knowledge. The sites we want to make are all pretty 'Web 2.0'ish', meaning user-generated content, commenting on posts, pages that change on the fly, etc. So here are some of my questions for anyone who's been there before: Is there a language you'd recommend learning first? Something that is a good indicator how most other languages work? What web programming languages do you recommend learning first based on popularity both now and the future. I don't want to learn a language that's going to be outdated by the time I'm an expert at it. Any specific books you'd recommend? Any general advice you'd give to someone literally starting at square zero for coding who plans on being in it for the long haul? Thanks in advance for the help

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  • How to Make a Game like Space Invaders - Ray Wenderlich (why do my space invaders scroll off screen)

    - by Erv Noel
    I'm following this tutorial(http://www.raywenderlich.com/51068/how-to-make-a-game-like-space-invaders-with-sprite-kit-tutorial-part-1) and I've run into a problem right after the part where I add [self determineInvaderMovementDirection]; to my GameScene.m file (specifically to my moveInvadersForUpdate method) The tutorial states that the space invaders should be moving accordingly after adding this piece of code but when I run they move to the left and they do not come back. I'm not sure what I am doing wrong as I have followed this tutorial very carefully. Any help or clarification would be greatly appreciated. Thanks in advance ! Here is the full GameScene.m #import "GameScene.h" #import <CoreMotion/CoreMotion.h> #pragma mark - Custom Type Definitions /* The type definition and constant definitions 1,2,3 take care of the following tasks: 1.Define the possible types of invader enemies. This can be used in switch statements later when things like displaying different sprites images for each enemy type. The typedef makes InvaderType a formal Obj-C type that is type checked for method arguments and variables.This is so that the wrong method argument is not used or assigned to the wrong variable. 2. Define the size of the invaders and that they'll be laid out in a grid of rows and columns on the screen. 3. Define a name that will be used to identify invaders when searching for them. */ //1 typedef enum InvaderType { InvaderTypeA, InvaderTypeB, InvaderTypeC } InvaderType; /* Invaders move in a fixed pattern: right, right, down, left, down, right right. InvaderMovementDirection tracks the invaders' progress through this pattern */ typedef enum InvaderMovementDirection { InvaderMovementDirectionRight, InvaderMovementDirectionLeft, InvaderMovementDirectionDownThenRight, InvaderMovementDirectionDownThenLeft, InvaderMovementDirectionNone } InvaderMovementDirection; //2 #define kInvaderSize CGSizeMake(24,16) #define kInvaderGridSpacing CGSizeMake(12,12) #define kInvaderRowCount 6 #define kInvaderColCount 6 //3 #define kInvaderName @"invader" #define kShipSize CGSizeMake(30, 16) //stores the size of the ship #define kShipName @"ship" // stores the name of the ship stored on the sprite node #define kScoreHudName @"scoreHud" #define kHealthHudName @"healthHud" /* this class extension allows you to add “private” properties to GameScene class, without revealing the properties to other classes or code. You still get the benefit of using Objective-C properties, but your GameScene state is stored internally and can’t be modified by other external classes. As well, it doesn’t clutter the namespace of datatypes that your other classes see. This class extension is used in the method didMoveToView */ #pragma mark - Private GameScene Properties @interface GameScene () @property BOOL contentCreated; @property InvaderMovementDirection invaderMovementDirection; @property NSTimeInterval timeOfLastMove; @property NSTimeInterval timePerMove; @end @implementation GameScene #pragma mark Object Lifecycle Management #pragma mark - Scene Setup and Content Creation /*This method simply invokes createContent using the BOOL property contentCreated to make sure you don’t create your scene’s content more than once. This property is defined in an Objective-C Class Extension found near the top of the file()*/ - (void)didMoveToView:(SKView *)view { if (!self.contentCreated) { [self createContent]; self.contentCreated = YES; } } - (void)createContent { //1 - Invaders begin by moving to the right self.invaderMovementDirection = InvaderMovementDirectionRight; //2 - Invaders take 1 sec for each move. Each step left, right or down // takes 1 second. self.timePerMove = 1.0; //3 - Invaders haven't moved yet, so set the time to zero self.timeOfLastMove = 0.0; [self setupInvaders]; [self setupShip]; [self setupHud]; } /* Creates an invade sprite of a given type 1. Use the invadeType parameterr to determine color of the invader 2. Call spriteNodeWithColor:size: of SKSpriteNode to alloc and init a sprite that renders as a rect of the given color invaderColor with size kInvaderSize */ -(SKNode*)makeInvaderOfType:(InvaderType)invaderType { //1 SKColor* invaderColor; switch (invaderType) { case InvaderTypeA: invaderColor = [SKColor redColor]; break; case InvaderTypeB: invaderColor = [SKColor greenColor]; break; case InvaderTypeC: invaderColor = [SKColor blueColor]; break; } //2 SKSpriteNode* invader = [SKSpriteNode spriteNodeWithColor:invaderColor size:kInvaderSize]; invader.name = kInvaderName; return invader; } -(void)setupInvaders { //1 - loop over the rows CGPoint baseOrigin = CGPointMake(kInvaderSize.width / 2, 180); for (NSUInteger row = 0; row < kInvaderRowCount; ++row) { //2 - Choose a single InvaderType for all invaders // in this row based on the row number InvaderType invaderType; if (row % 3 == 0) invaderType = InvaderTypeA; else if (row % 3 == 1) invaderType = InvaderTypeB; else invaderType = InvaderTypeC; //3 - Does some math to figure out where the first invader // in the row should be positioned CGPoint invaderPosition = CGPointMake(baseOrigin.x, row * (kInvaderGridSpacing.height + kInvaderSize.height) + baseOrigin.y); //4 - Loop over the columns for (NSUInteger col = 0; col < kInvaderColCount; ++col) { //5 - Create an invader for the current row and column and add it // to the scene SKNode* invader = [self makeInvaderOfType:invaderType]; invader.position = invaderPosition; [self addChild:invader]; //6 - update the invaderPosition so that it's correct for the //next invader invaderPosition.x += kInvaderSize.width + kInvaderGridSpacing.width; } } } -(void)setupShip { //1 - creates ship using makeShip. makeShip can easily be used later // to create another ship (ex. to set up more lives) SKNode* ship = [self makeShip]; //2 - Places the ship on the screen. In SpriteKit the origin is at the lower //left corner of the screen. The anchorPoint is based on a unit square with (0, 0) at the lower left of the sprite's area and (1, 1) at its top right. Since SKSpriteNode has a default anchorPoint of (0.5, 0.5), i.e., its center, the ship's position is the position of its center. Positioning the ship at kShipSize.height/2.0f means that half of the ship's height will protrude below its position and half above. If you check the math, you'll see that the ship's bottom aligns exactly with the bottom of the scene. ship.position = CGPointMake(self.size.width / 2.0f, kShipSize.height/2.0f); [self addChild:ship]; } -(SKNode*)makeShip { SKNode* ship = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:kShipSize]; ship.name = kShipName; return ship; } -(void)setupHud { //Sets the score label font to Courier SKLabelNode* scoreLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //1 - Give the score label a name so it becomes easy to find later when // the score needs to be updated. scoreLabel.name = kScoreHudName; scoreLabel.fontSize = 15; //2 - Color the score label green scoreLabel.fontColor = [SKColor greenColor]; scoreLabel.text = [NSString stringWithFormat:@"Score: %04u", 0]; //3 - Positions the score label near the top left corner of the screen scoreLabel.position = CGPointMake(20 + scoreLabel.frame.size.width/2, self.size.height - (20 + scoreLabel.frame.size.height/2)); [self addChild:scoreLabel]; //Applies the font of the health label SKLabelNode* healthLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //4 - Give the health label a name so it can be referenced later when it needs // to be updated to display the health healthLabel.name = kHealthHudName; healthLabel.fontSize = 15; //5 - Colors the health label red healthLabel.fontColor = [SKColor redColor]; healthLabel.text = [NSString stringWithFormat:@"Health: %.1f%%", 100.0f]; //6 - Positions the health Label on the upper right hand side of the screen healthLabel.position = CGPointMake(self.size.width - healthLabel.frame.size.width/2 - 20, self.size.height - (20 + healthLabel.frame.size.height/2)); [self addChild:healthLabel]; } #pragma mark - Scene Update - (void)update:(NSTimeInterval)currentTime { //Makes the invaders move [self moveInvadersForUpdate:currentTime]; } #pragma mark - Scene Update Helpers //This method will get invoked by update -(void)moveInvadersForUpdate:(NSTimeInterval)currentTime { //1 - if it's not yet time to move, exit the method. moveInvadersForUpdate: // is invoked 60 times per second, but you don't want the invaders to move // that often since the movement would be too fast to see if (currentTime - self.timeOfLastMove < self.timePerMove) return; //2 - Recall that the scene holds all the invaders as child nodes; which were // added to the scene using addChild: in setupInvaders identifying each invader // by its name property. Invoking enumerateChildNodesWithName:usingBlock only loops over the invaders because they're named kInvaderType; which makes the loop skip the ship and the HUD. The guts og the block moves the invaders 10 pixels either right, left or down depending on the value of invaderMovementDirection [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionLeft: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionDownThenLeft: case InvaderMovementDirectionDownThenRight: node.position = CGPointMake(node.position.x, node.position.y - 10); break; InvaderMovementDirectionNone: default: break; } }]; //3 - Record that you just moved the invaders, so that the next time this method is invoked (1/60th of a second from when it starts), the invaders won't move again until the set time period of one second has elapsed. self.timeOfLastMove = currentTime; //Makes it so that the invader movement direction changes only when the invaders are actually moving. Invaders only move when the check on self.timeOfLastMove passes (when conditional expression is true) [self determineInvaderMovementDirection]; } #pragma mark - Invader Movement Helpers -(void)determineInvaderMovementDirection { //1 - Since local vars accessed by block are default const(means they cannot be changed), this snippet of code qualifies proposedMovementDirection with __block so that you can modify it in //2 __block InvaderMovementDirection proposedMovementDirection = self.invaderMovementDirection; //2 - Loops over the invaders in the scene and refers to the block with the invader as an argument [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: //3 - If the invader's right edge is within 1pt of the right edge of the scene, it's about to move offscreen. Sets proposedMovementDirection so that the invaders move down then left. You compare the invader's frame(the frame that contains its content in the scene's coordinate system) with the scene width. Since the scene has an anchorPoint of (0,0) by default and is scaled to fill it's parent view, this comparison ensures you're testing against the view's edges. if (CGRectGetMaxX(node.frame) >= node.scene.size.width - 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenLeft; *stop = YES; } break; case InvaderMovementDirectionLeft: //4 - If the invader's left edge is within 1 pt of the left edge of the scene, it's about to move offscreen. Sets the proposedMovementDirection so invaders move down then right if (CGRectGetMinX(node.frame) <= 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenRight; *stop = YES; } break; case InvaderMovementDirectionDownThenLeft: //5 - If invaders are moving down then left, they already moved down at this point, so they should now move left. proposedMovementDirection = InvaderMovementDirectionLeft; *stop = YES; break; case InvaderMovementDirectionDownThenRight: //6 - if the invaders are moving down then right, they already moved down so they should now move right. proposedMovementDirection = InvaderMovementDirectionRight; *stop = YES; break; default: break; } }]; //7 - if the proposed invader movement direction is different than the current invader movement direction, update the current direction to the proposed direction if (proposedMovementDirection != self.invaderMovementDirection) { self.invaderMovementDirection = proposedMovementDirection; } } #pragma mark - Bullet Helpers #pragma mark - User Tap Helpers #pragma mark - HUD Helpers #pragma mark - Physics Contact Helpers #pragma mark - Game End Helpers @end

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  • Numerical calculations in Prolog

    - by user8472
    While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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  • PHP/WordPress Session CountDown

    - by Cameron
    I have the following code to show how long a user has left before their session will expire, I am using WordPress. How can I do this? Thanks <script> var obj_Span; var n_Seconds = 0; var n_Minutes = 0; var n_Hours = 0; function F_ConvertNumberToString ( n_Num ) { var str_Num = String(n_Num); if ( str_Num.length < 2 ) str_Num = "0" + str_Num; return str_Num; } function F_CountDown () { if ( n_Hours == 0 && n_Minutes == 0 && n_Seconds == 0 ) { obj_Span.innerHTML = "(Sorry, your session has expired.)"; } else { if ( n_Seconds >= 0 ) n_Seconds --; if ( n_Seconds < 0 ) { n_Minutes --; n_Seconds = 59; } if ( n_Minutes >= 0 ) { window.setTimeout ( "F_CountDown()", 1000 ); } if ( n_Minutes < 0 ) { n_Hours --; n_Minutes = 59; window.setTimeout ( "F_CountDown()", 1000 ); } F_UpdateDisplay (); } } function F_UpdateDisplay ( ) { if ( document.getElementById ) { if (n_Hours > 0 ) obj_Span.innerHTML = "(Remaining " + F_ConvertNumberToString(n_Hours) + ":" + F_ConvertNumberToString(n_Minutes) + ":" + F_ConvertNumberToString(n_Seconds) + ")"; else obj_Span.innerHTML = "(Remaining " + F_ConvertNumberToString(n_Minutes) + ":" + F_ConvertNumberToString(n_Seconds) + ")"; } } function F_StartCountDown ( n_Session ) { obj_Span = document.getElementById ( "CountDown" ); n_Minutes = n_Session; n_Hours = Math.floor(n_Minutes/60); n_Minutes = n_Minutes - (60*n_Hours); F_CountDown (); } </script> <script> F_StartCountDown ( " code here... " ); </script> <span id="CountDown"></span>

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