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• How do I fix broken installation?

  - by Daniel

  Let me start off by saying I'm dual booting 11.04 and Windows 7 on a Thinkpad T61p. The problem may have arisen when I hit the power button during normal startup. I'm fully aware how stupid this is. I don't know why I did it. I did it. Now, I can't get in to Ubuntu. Windows works fine. But when I try to start Ubuntu normally, it seems to run some checks, and does not start up. Sometimes, I see a black screen, and it tells me that it's running certain checks, and then, [ok]. Like... Battery Check Somethingorother [ok] It'll give me 1-5 of these. And then it just does nothing, and I have to turn it off. When I try to start in safe mode... I tried low graphics mode, and after going through a couple of dialogue boxes, I'm brought right back to the safe mode dialogue box. And if I hit 'resume,' a shell pushes up (still that grey on black "your computer is broken" type shell) and asks me to log in. I do, and try to run unity. It tells me something along the lines of: WARNING no DISPLAY variable set and then sets it to " :0" , which doesn't work. And then I can't do anything, really, and I have to restart. (I don't know how to do this from the command line, so I just hard reset. That command would be helpful). Does anybody have any idea how I can get Ubuntu working right again? FTP is less pleasant in Explorer than it is in Nautilus or w/e it is now.

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• Input of mouseclick not always registered in XNA Update method

  - by LordrAider

  I have a problem that not all inputs of my mouse events seem to be registered. The update logic is checking a 2 dimensional array of 10x10 . It's logic for a jewel matching game. So when i switch my jewel I can't click on another jewel for like half a second. I tested it with a click counter variable and it doesn't hit the debugger when i click the second time after the jewel switch. Only if I do the second click after waiting half a second longer. Could it be that the update logic is too heavy that while he is executing update logic my click is happening and he doesn't register it? What am I not seeing here :)? Or doing wrong. It is my first game. My function of the update methode looks like this. public void UpdateBoard() { MouseState currentMouseState; currentMouseState = Mouse.GetState(); if (currentMouseState.LeftButton == ButtonState.Pressed && prevMouseState.LeftButton != ButtonState.Pressed) { UpdatingLogic = true; // this.CheckDropJewels(currentMouseState); //this.CheckMatches(3); //this.RemoveMatches(); this.CheckForSwitch(currentMouseState); this.MarkJewel(currentMouseState); UpdatingLogic = false; //reIndexMissingJewels = true; reIndexSwitchedJewels = true; } prevMouseState = currentMouseState; this.ReIndex(); this.UpdateJewels(); }

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• What are some techniques I can use to refactor Object Oriented code into Functional code?

  - by tieTYT

  I've spent about 20-40 hours developing part of a game using JavaScript and HTML5 canvas. When I started I had no idea what I was doing. So it started as a proof of concept and is coming along nicely now, but it has no automated tests. The game is starting to become complex enough that it could benefit from some automated testing, but it seems tough to do because the code depends on mutating global state. I'd like to refactor the whole thing using Underscore.js, a functional programming library for JavaScript. Part of me thinks I should just start from scratch using a Functional Programming style and testing. But, I think refactoring the imperative code into declarative code might be a better learning experience and a safer way to get to my current state of functionality. Problem is, I know what I want my code to look like in the end, but I don't know how to turn my current code into it. I'm hoping some people here could give me some tips a la the Refactoring book and Working Effectively With Legacy Code. For example, as a first step I'm thinking about "banning" global state. Take every function that uses a global variable and pass it in as a parameter instead. Next step may be to "ban" mutation, and to always return a new object. Any advice would be appreciated. I've never taken OO code and refactored it into Functional code before.

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• Matrices: Arrays or separate member variables?

  - by bjz

  I'm teaching myself 3D maths and in the process building my own rudimentary engine (of sorts). I was wondering what would be the best way to structure my matrix class. There are a few options: Separate member variables: struct Mat4 { float m11, m12, m13, m14, m21, m22, m23, m24, m31, m32, m33, m34, m41, m42, m43, m44; // methods } A multi-dimensional array: struct Mat4 { float[4][4] m; // methods } An array of vectors struct Mat4 { Vec4[4] m; // methods } I'm guessing there would be positives and negatives to each. From 3D Math Primer for Graphics and Game Development, 2nd Edition p.155: Matrices use 1-based indices, so the first row and column are numbered 1. For example, a12 (read “a one two,” not “a twelve”) is the element in the first row, second column. Notice that this is different from programming languages such as C++ and Java, which use 0-based array indices. A matrix does not have a column 0 or row 0. This difference in indexing can cause some confusion if matrices are stored using an actual array data type. For this reason, it’s common for classes that store small, fixed size matrices of the type used for geometric purposes to give each element its own named member variable, such as float a11, instead of using the language’s native array support with something like float elem[3][3]. So that's one vote for method one. Is this really the accepted way to do things? It seems rather unwieldy if the only benefit would be sticking with the conventional math notation.

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• Totem crashes immediately after startup in 12.10

  - by Sakib Hasan

  I did a fresh install of Ubuntu 12.10 and did sudo apt-get update && sudo apt-get update. Then I installed ubuntu-restricted-extras, audacious and vlc from Software Center. After that I tried launch Totem Movie player but in terminal following error comes up: (totem:9295): Gdk-ERROR **: The program 'totem' received an X Window System error. This probably reflects a bug in the program. The error was 'BadDrawable (invalid Pixmap or Window parameter)'. (Details: serial 1808 error_code 9 request_code 152 minor_code 9) (Note to programmers: normally, X errors are reported asynchronously; that is, you will receive the error a while after causing it. To debug your program, run it with the GDK_SYNCHRONIZE environment variable to change this behavior. You can then get a meaningful backtrace from your debugger if you break on the gdk_x_error() function.) Trace/breakpoint trap (core dumped) I tried purge and again install. But the error remains. What should I do?

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• Where to find common database abbreviations in Spanish

  - by jmh_gr

  I'm doing a little pro bono work for an organization in Central America. I'm ok at Spanish and my contacts are perfectly fluent but are not techincal people. Even if they don't care what I call some fields in a database I still want to make as clean a schema as possible, and I'd like to know what some typical abbreviations are for field / variable names in Spanish. I understand abbreviations and naming conventions are entirely personal. I'm not asking for the "correct" or "best" way to abbreviate database object names. I'm just looking for references to lists of typical abbreviations that would be easily recognizable to a techincally competent native Spanish speaker. I believe I am a decent googler but I've had no luck on this one. For example, in my company (where English is the primary language) 'Date' is always shortened to 'DT', 'Code' to 'CD', 'Item' to 'IT', etc. It's easy for the crowds of IT temp workers who revolve through on various projects to figure out that 'DT' stands for 'Date', 'YR' for 'Year', or 'TN' for 'Transaction' without even having to consult the official abbreviations list.

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• Designing communications for extensibility

  - by Thomas S.

  I am working on the design stages of an application that will a) collect data from various sources (in my case that's scientific data from serial ports), keeping track of the age of the data, b) generate real-time statistics (e.g. running averages) c) display, record, and otherwise handle the data (and statistics). I anticipate that I will be adding both data producers and consumers over time, and would like to design this application abstractly so that I will be able to trivially add functionality with a small amount of interface code. What I'm stumbling on is deciding what communication infrastructure I should use to handle the interfaces. In particular, how should I make the processed data and statistics available to multiple consumers? Some things I've considered: Writing to several named pipes (variable number). Each consumer reads from one of them. Using FUSE to make a userspace filesystem where a read() returns the latest line of data even if another process has already read it. Making a TCP server, and having consumers connect and request data individually. Simply writing the consumers as part of the same program that aggregates the data. So I would like to hear your all's advice on deciding how to interface these functions in the best way to keep them separate and allow room for extenstions.

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• Boundary conditions for testing

  - by Loggie

  Ok so in a programming test I was given the following question. Question 1 (1 mark) Spot the potential bug in this section of code: void Class::Update( float dt ) { totalTime += dt; if( totalTime == 3.0f ) { // Do state change m_State++; } } The multiple choice answers for this question were. a) It has a constant floating point number where it should have a named constant variable b) It may not change state with only an equality test c) You don't know what state you are changing to d) The class is named poorly I wrongly answered this with answer C. I eventually received feedback on the answers and the feedback for this question was Correct answer is a. This is about understanding correct boundary conditions for tests. The other answers are arguably valid points, but do not indicate a potential bug in the code. My question here is, what does this have to do with boundary conditions? My understanding of boundary conditions is checking that a value is within a certain range, which isn't the case here. Upon looking over the question, in my opinion, B should be the correct answer when considering the accuracy issues of using floating point values.

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• Installing Django on Windows

  - by Pranav

  Ever needed to install Django in a Microsoft Windows environment, here is a quick start guide to make that happen: Read through the official Django installation documentation, it might just save you a world of hut down the road. Download Python for your version of Windows. Install Python, my preference here is to put it into the Program Files folder under a folder named Python<Version> Add your chosen Python installation path into your Windows path environment variable. This is an optional step, however it allows you to just type python in the command line and have it fire up the Python interpreter. An easy way of adding it is going into Control Panel, System and into the Environment Variables section. Download Django, you can either download a compressed file or if you’re comfortable with using version control – check it out from the Django Subversion repository. Create a folder named django under your <Python installation directory>\Lib\site-packages\ folder. Using my example above that would have been C:\Program Files\Python25\Lib\site-packages\. If you chose to download the compressed file, open it and extract the contents of the django folder into your newly created folder. If you’d prefer to check it out from Subversion, the normal check out points are http://code.djangoproject.com/svn/django/trunk/ for the latest development copy or a named release which you’ll find under http://code.djangoproject.com/svn/django/tags/releases/. Done, you now have a working Django installation on Windows. At this point, it’d be pertinent to confirm that everything is working properly, which you can do by following the first Django tutorial. The tutorial will make mention of django-admin.py, which is a utility which offers some basic functionality to get you off the ground. The file is located in the bin folder under your Django installation directory. When you need to use it, you can either type in the full path to it or simply add that file path into your environment variables as well. Hope this helps!

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• What’s ‘default’ for?

  - by Strenium

  Sometimes there's a need to communicate explicitly that value variable is yet to be "initialized" or in other words - we’ve never changed it from its' default value. Perhaps "initialized" is not the right word since a value type will always have some sort of value (even a nullable one) but it's just that - how do we tell? Of course an 'int' would be 0, an 'enum' would the first defined value of a given enum and so on – we sure can make this kind of check "by hand" but eventually it would get a bit messy. There's a more elegant way with a use of little-known functionality of: 'default'Let’s just say we have a simple Enum: Simple Enum namespace xxx.Common.Domain{    public enum SimpleEnum    {        White = 1,         Black = 2,         Red = 3    }}   In case below we set the value of the enum to ‘White’ which happens to be a first and therefore default value for the enum. So the snippet below will set value of the ‘isDefault’ Boolean to ‘true’. 'True' Case SimpleEnum simpleEnum = SimpleEnum.White;bool isDefault; /* btw this one is 'false' by default */ isDefault = simpleEnum == default(SimpleEnum) ? true : false; /* default value 'white' */   Here we set the value to ‘Red’ and ‘default’ will tell us whether or not this the default value for this enum type. In this case: ‘false’. 'False' Case simpleEnum = SimpleEnum.Red; /* change from default */isDefault = simpleEnum == default(SimpleEnum) ? true : false; /* value is not default any longer */ Same 'default' functionality can also be applied to DateTimes, value types and other custom types as well. Sweet ‘n Short. Happy Coding!

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• Trying to make a game with C++, using lists to store bullets and enemies, but they are not erased

  - by XD_dued

  I've been trying to make a pretty simple space shooter game with C++, and I have been having a lot of trouble trying to use lists to store enemies and bullets. Basically I followed the post here almost exactly to store my bullets: SDL Bullet Movement I've done something similar to store my enemies. However, when I call bullets.erase(it++), for some reason the bullet is not erased. When the bullet movement is run for the next frame, it tries to re delete the bullet and segfaults the program. When I comment out the erase line, it runs fine, but the bullets are then never erased from the list... Is there any reason why the elements of the list aren't being deleted? I also set it up to print the number of elements in the list for every iteration, and it does not go down after deleting. Thanks! EDIT: Here's the specific code I'm using to store my enemies and having them act: std::list<Grunt*> doGrunts(std::list<Grunt*> grunts) { for(std::list<Grunt*>::iterator it = grunts.begin(); it != grunts.end();) { if((*it)->getHull() == 0) { delete * it; grunts.erase(it++); } else { (**it).doUnit(grunts, it); ++it; } } } Grunt is my enemy class, and the list grunts is a global variable. Is that my problem? When I pass the global into the function it becomes local? I assumed lists would be a reference type so thought this wouldn't be a problem. Sorry if this was a dumb question, I'm very new to C++, this is the first major thing I'm working on.

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• Finite Numbers and ExplorerCanvas

  - by PhubarBaz

  I was working on my online mathematical graphing application, CloudGraph, and trying to make it work in IE. The app uses the HTML5 canvas element to draw graphs. Since IE doesn't support canvas yet I use ExplorerCanvas to provide that support for IE. However, it seems that when using excanvas, if you try to moveTo or drawTo a point that is not finite it loses it's mind and stops drawing anything else after that. I had no such problems in Firefox or Chrome so it took me awhile to figure out what was going on. Next I discovered that I needed a way to check if a variable was NaN or Inifinity or any other non-finite value so I could avoid calling moveTo() in that case. I started writing a long if statement, then I thought there has to be a better way. Sure enough there was. There just happens to be an isFinite() function built into Javascript just for this purpose. Who knew! It works great. Another difference I discovered with excanvas is that you must specify a starting point using a moveTo() when beginning a drawing path. Again, Chrome and Firefox are a lot more forgiving in this area so it took me a while to figure out why my lines weren't drawing. But, all is happy now and I'm a little wiser to the ways of the canvas.

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• why does array initialization in function other than main is temporary? [on hold]

  - by shafeeq

  This is the code in which i initialize array "turn[20]" in main as well as in function "checkCollisionOrFood()",the four values turn[0],turn[1],turn[2],turn[3] are initialized to zero in main function,rest are being intialized in "checkCollisionOrFood()".This is where fault starts.when i initialize turn[4]=0 in "checkCollisionOrFood()" and then access it anywhere,it remains 0 in any function,but! when i initialize next turn[] i.e turn[5],the value of turn[4] gets depleted .i.e turn[4] have garbage value.turn[20] is global variable,its index"head" is also global.I'm stuck.Plz help me get out of it.Ishall be highly obliged for this act of kindness.This is my excerpt of code unsigned short checkCollisionOrFood(){ head=(head+1)%20; if(turn[head-1]==0){ turn[head]=0; /this is where turn[] is iniliazized and if i access turn[head] here i.e just after iniliazition then it gives correct value but if i access its previous value means turn[head-1]then it gives garbage value/ rowHead=(rowHead+1)%8; if(!(address[colHead]&(1<<rowHead)))return 1; else if((address[colHead]&(1<<rowHead))&& (!((colHead==foody)&&(rowHead==foodx))))gameOver(); else return 0; } if(turn[head-1]==1){ turn[head]=1; colHead=(colHead+1)%8; if(!(address[colHead]&(1<<rowHead)))return 1; else if((address[colHead]&(1<<rowHead))&& (!((colHead==foody)&&(rowHead==foodx))))gameOver(); else return 0; } } void main(void) { turn[0]=0;turn[1]=0;turn[2]=0;turn[3]=0; /these values of turn[] are not changed irrespective of where they are accessed./ while (1) { if(checkCollisionOrFood()) { PORTB=(address[colHead] |=1<<rowHead); turnOffTail(); blink(); } else { PORTB=address[colHead]; createFood(); blink(); } } } Plz help me.

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• What is the standard technique for shifting the frames of a sprite according to user input?

  - by virtual__

  From my own experience, I developed two techniques for changing the sprites of a character that's reacting to user input -- this in the context of a classic 2D platformer. The first one is to store all character's pixmaps in a list, putting the index of the currently used pixmap in an ordinary variable. This way, every time the player presses a key -- say the right arrow for moving the character forward -- the graphics engine sees what's the next pixmap to draw, draws it, and increments the index counter. That's a pretty common approach I believe, the problem is that in this case the animation's quality depends not only on the number of sprites available but also on how often your engine listens to user input. The second technique is to actually play an animation every key press event. For this you can use any sort of animation framework you want. It's only necessary to set the timer, the animation steps and to call the animation's play() method on your key press event handler. The problem with that approach is that is lacks responsiveness, since the character won't react to any input while the current animation is still being played. What I want to know is whether you are using one of these techniques -- or something similar -- in your games, or whether there's a standard method for animating sprites out there that's widely known by everybody but me.

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• Booting off a ZFS root in 14.04

  - by RJVB

  I've been running a Debian derivative (LMDE) on a ZFS root for half a year now. It was created by cloning a regular ext4-based install with all the necessary packages onto a ZFS pool, chrooting into that pool and recreating a grub menu and bootloader. The system uses an ext-3 dedicated /boot partition. I would like to do the same with Ubuntu 14.04, but have encountered several obstacles. There is no Trusty zfs-grub package The default grub package doesn't have ZFS support built in. I found a small bug in the build system responsible for that (report with patch created) and built my own grub packages. The built-in ZFS support is dysfunctional, it does not add the proper arguments to the kernel command line I thus installed the ZoL grub package I also use on my LMDE system, which does give me a correct grub.cfg However, even with that correct grub.cfg, the boot process apparently doesn't retrieve the bootfs parameter from the ZFS pool; instead the variable that's supposed to receive the value remains empty. As a result, initrd tries to load the default pool ("rpool"), which fails of course. I can however import the pool by hand, and complete the process by hand. If memory serves me well, I also had to disable apparmor, to avoid the boot process from blocking after importing the pool. Am I overlooking something? Just for comparison, I installed the Ubuntu 3.13 kernel on my LMDE system, and that works just fine (i.e. the identical kernel and grub binaries allow successful booting without glitches on LMDE but not on Ubuntu).

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• CUDA 4.1 Update

  - by N0xus

  I'm currently working on porting a particle system to update on the GPU via the use of CUDA. With CUDA, I've already passed over the required data I need to the GPU and allocated and copied the date via the host. When I build the project, it all runs fine, but when I run it, the project says I need to allocate my h_position pointer. This pointer is my host pointer and is meant to hold the data. I know I need to pass in the current particle position to the required cudaMemcpy call and they are currently stored in a list with a for loop being created and interated for each particle calling the following line of code: m_particleList[i].positionY = m_particleList[i].positionY - (m_particleList[i].velocity * frameTime * 0.001f); My current host side cuda code looks like this: float* h_position; // Your host pointer. This holds the data (I assume it's already filled with the data.) float* d_position; // Your device pointer, we will allocate and fill this float* d_velocity; float* d_time; int threads_per_block = 128; // You should play with this value int blocks = m_maxParticles/threads_per_block + ( (m_maxParticles%threads_per_block)?1:0 ); const int N = 10; size_t size = N * sizeof(float); cudaMalloc( (void**)&d_position, m_maxParticles * sizeof(float) ); cudaMemcpy( d_position, h_position, m_maxParticles * sizeof(float), cudaMemcpyHostToDevice); Both of which were / can be found inside my UpdateParticle() method. I had originally thought it would be a simple case of changing the h_position variable in the cudaMemcpy to m_particleList[i] but then I get the following error: no suitable conversion function from "ParticleSystemClass::ParticleType" to "const void *" exists I've probably messed up somewhere, but could someone please help fix the issues I'm facing. Everything else seems to running fine, it's just when I try to run the program that certain things hit the fan.

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• Proper way to encapsulate a Shader into different modules

  - by y7haar

  I am planning to build a Shader system which can be accessed through different components/modules in C++. Each component has its own functionality like transform-relevated stuff (handle the MVP matrix, ...), texture handler, light calculation, etc... So here's an example: I would like to display an object which has a texture and a toon shading material applied and it should be moveable. So I could write ONE shading program that handles all 3 functionalities and they are accessed through 3 different components (texture-handler, toon-shading, transform). This means I have to take care of feeding a GLSL shader with different uniforms/attributes. This implies to know all necessary uniform locations and attribute locations, that the GLSL shader owns. And it would also necessary to provide different algorithms to calculate the value for each input variable. Similar functions would be grouped together in one component. A possible way would be, to wrap all shaders in a own definition file written in JSON/XML and parse that file in C++ to get all input members and create and compile the resulting GLSL. But maybe there is another way that is not so complex? So I'm searching for a way to build a system like that, but I'm not sure yet which is the best approach.

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• 7 drived classes with one common base class

  - by user144905

  i have written the following code, //main.cpp #include<iostream> #include<string> #include"human.h" #include"computer.h" #include"referee.h" #include"RandomComputer.h" #include"Avalanche.h" #include"Bureaucrat.h" #include"Toolbox.h" #include"Crescendo.h" #include"PaperDoll.h" #include"FistfullODollors.h" using namespace std; int main() { Avalanche pla1; Avalanche pla2; referee f; pla1.disp(); for (int i=0;i<5;i++) { cout<<pla2.mov[i]; } return 0; } in this program all included classes except referee.h and human.h are drived from computer.h. each drived calls has a char array variable which is initialized when a member of a drived class is declared. the problem is that when i declare tow diffrent drived class memebers lets say Avalache and ToolBox. upon printing the char array for one of them using for loop it prints nothing. However if i declare only one of them in main.cpp the it works properly. and the file for computer.h is as such: #ifndef COMPUTER_H #define COMPUTER_H class computer { public: int nump; char mov[]; void disp(); }; #endif ToolBox.h is like this: #ifndef TOOLBOX_H #define TOOLBOX_H #include"computer.h" class Toolbox: public computer { public: Toolbox(); }; #endif finally Avalanche.h is as following: #ifndef AVALANCHE_H #define AVALANCHE_H #include"computer.h" class Avalanche: public computer { public: Avalanche(); }; #endif

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• Google Analytics custom variables and how are they recorded?

  - by mrtsherman

  I have been asked to add GA custom variable tracking to my company's website. The company website uses server side includes, so making modifications to the tracking code happens identically everywhere. Maintenance is therefore a headache. Also, GA takes about twenty-four hours for custom variables to start showing up in reports and that makes troubleshooting a headache. So if you have custom variables // visitor level tracking, id = 12345 _gaq.push(['_setCustomVar', 1, 'id', '12345', 1]); // page level tracking, email = [email protected] _gaq.push(['_setCustomVar', 1, 'email', '[email protected]', 1]); The marketing people want the following out of this: User visits site and we record a unique id for them. Whenever they return this id will be used in GA. User signs up for our newsletter on page X and we record their email address. Whenever they return this email address is used in GA. Now a big problem for me is that I don't use GA and the marketing people don't use custom variables. So we don't actually know how this will work. Do I want Page, Session or Visitor level tracking? What happens because the same GA code is used on every page? If they visit the email sign up form and we record the email address, but then they go somewhere else where email is nonexistent will the value get 'overwritten.' Sorry for the long question, but there are a lot of unknowns for a GA noob.

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• Most efficient way to store this collection of moduli and remainders?

  - by Bryan

  I have a huge collection of different moduli and associated with each modulus a fairly large list of remainders. I want to store these values so that I can efficiently determine whether an integer is equivalent to any one of the remainders with respect to any of the moduli (it doesn't matter which, I just want a true/false return). I thought about storing these values as a linked-list of balanced binary trees, but I was wondering if there is a better way? EDIT Perhaps a little more detail would be helpful. As for the size of this structure, it will be holding about 10s of thousands of (prime-1) moduli and associated to each modulus will be a variable amount of remainders. Most moduli will only have one or two remainders associated to it, but a very rare few will have a couple hundred associated to it. This is part of a larger program which handles numbers with a couple thousand (decimal) digits. This program will benefit more from this table being as large as possible and being able to be searched quickly. Here's a small part of the dataset where the moduli are in parentheses and the remainders are comma separated: (46) k = 20 (58) k = 15, 44 (70) k = 57 (102) k = 36, 87 (106) k = 66 (156) k = 20, 59, 98, 137 (190) k = 11, 30, 68, 87, 125, 144, 182 (430) k = 234 (520) k = 152, 282 (576) k = 2, 11, 20, 29, 38, 47, 56, 65, 74, ...(add 9 each time), 569 I had said that the moduli were prime, but I was wrong they are each one below a prime.

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• Is it reasonable to null guard every single dereferenced pointer?

  - by evadeflow

  At a new job, I've been getting flagged in code reviews for code like this: PowerManager::PowerManager(IMsgSender* msgSender) : msgSender_(msgSender) { } void PowerManager::SignalShutdown() { msgSender_->sendMsg("shutdown()"); } I'm told that last method should read: void PowerManager::SignalShutdown() { if (msgSender_) { msgSender_->sendMsg("shutdown()"); } } i.e., I must put a NULL guard around the msgSender_ variable, even though it is a private data member. It's difficult for me to restrain myself from using expletives to describe how I feel about this piece of 'wisdom'. When I ask for an explanation, I get a litany of horror stories about how some junior programmer, some-year, got confused about how a class was supposed to work and accidentally deleted a member he shouldn't have (and set it to NULL afterwards, apparently), and things blew up in the field right after a product release, and we've "learned the hard way, trust us" that it's better to just NULL check everything. To me, this feels like cargo cult programming, plain and simple. A few well-meaning colleagues are earnestly trying to help me 'get it' and see how this will help me write more robust code, but... I can't help feeling like they're the ones who don't get it. Is it reasonable for a coding standard to require that every single pointer dereferenced in a function be checked for NULL first—even private data members? (Note: To give some context, we make a consumer electronics device, not an air traffic control system or some other 'failure-equals-people-die' product.) EDIT: In the above example, the msgSender_ collaborator isn't optional. If it's ever NULL, it indicates a bug. The only reason it is passed into the constructor is so PowerManager can be tested with a mock IMsgSender subclass.

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• Problem with gluOrtho2D()

  - by Shashwat

  I was trying to understand the gluOrtho2D function. I have drawn 4 lines originating from the center reaching up to 4 corners of the screen. You can follow the below code. osize is a variable which is used to set the parameters of gluOrtho2D. It will create a window of size 2*osize. If works fine when osize is 1. Lines reach the corners. But as I increase the value of osize, the length of the lines decreases (cross becomes smaller and does not cover the whole screen). But I think it should reach the corner. void display() { glClear( GL_COLOR_BUFFER_BIT ); //glViewport(0, 0, 100, 100); glMatrixMode (GL_PROJECTION); float osize = 1.2; //glOrtho(-osize*1.0, osize*1.0, osize*1.0, -osize*1.0, -1.0, 1.0); gluOrtho2D(-osize*1.0, osize*1.0, osize*1.0, -osize*1.0); glMatrixMode (GL_MODELVIEW); glBegin(GL_LINES); glColor3f(0.0, 0.0, 1.0); glVertex2f(0.0, 0.0); glVertex2f(-osize*1.0, -osize*1.0); glVertex2f(0.0, 0.0); glVertex2f(-osize*1.0, osize*1.0); glVertex2f(0.0, 0.0); glVertex2f(osize*1.0, -osize*1.0); glVertex2f(0.0, 0.0); glVertex2f(osize*1.0, osize*1.0); glEnd(); glutSwapBuffers(); //includes glFlush(); } What is the problem?

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• How to input data into user defined variables into MySql query

  - by user292791

  Simple Shell script echo "Enter 1 for month of March" echo "Enter 2 for month of April" echo "Enter 3 for month of May" read Month case "$Month" in 1) echo "enter establishment name" read a; mysql -u root -p $a < "March.sql";; 2) echo "enter establishment name" read b; mysql -u root -p $b < "April.sql";; 3) echo "enter establishment name" read c; mysql -u root -p $c < "May.sql";; esac done In this i have three other query files March.sql, April.sql, May.sql. i'm linking this in shell script . Example of .sql file: SELECT DISTINCT substr( a.case_no, 3, 2 ), b.case_type, b.type_name, a.case_no into outfile '/tmp/April.csv' FIELDS TERMINATED BY ',' ENCLOSED BY '"' LINES TERMINATED BY '\r\n' FROM Civil_t AS a, Case_type_t AS b, disposal_proc AS c WHERE substr( a.case_no, 3, 2 ) = b.case_type AND a.date_of_decision BETWEEN '2014-04-01' AND '2014-04-30' AND a.case_no = c.case_no AND a.court_no =1; I have to alter the .sql script every time. Is there any method to read the variables from shell script and use it in mysql. For example:- echo "enter date" read a #input date Now i have read a "date" and i want to use it in March.sql query in where clause. Is there is any method of using this variable in .sql query.

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• Movement on the X an Z axis are combined?

  - by Magicaxis

  This is probably a stupid question, but I'm trying to simply move a 3D object up, down, left, and right (Not forward or backward). The Y axis works fine, but when I increment the object's X position, the object moves BOTH right and backwards! when I decrement X, left and forwards! setPosition(getPosition().X + 2/*times deltatime*/, getPosition().Y, getPosition().Z); I was astonished that XNA doesnt have its own setPosition function, so I made a parent class for all objects with a setPosition and Draw function. Setposition simply edits a variable "mPosition" and passes it to the common draw function: // Copy any parent transforms. Matrix[] transforms = new Matrix[block.Bones.Count]; block.CopyAbsoluteBoneTransformsTo(transforms); // Draw the model. A model can have multiple meshes, so loop. foreach (ModelMesh mesh in block.Meshes) { // This is where the mesh orientation is set, as well // as our camera and projection. foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(MathHelper.ToRadians(mOrientation.Y)) * Matrix.CreateTranslation(mPosition); effect.View = game1.getView(); effect.Projection = game1.getProjection(); } // Draw the mesh, using the effects set above. mesh.Draw(); } I tried to work it out by attempting to increment and decrement the Z axis, but nothing happens?! So using the X axis changes the objects x and z axis', but changing the Z does nothing. Great. So how do I seperate the X and Z axis movement?

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• Trouble with collision detection in XNA?

  - by Lewis Wilcock

  I'm trying to loop through an list of enemies (enemyList) and then any that have intersected the rectangle belonging to the box object (Which doesn't move), declare there IsAlive bool as false. Then another part of the code removes any enemies that have the IsAlive bool as false. The problem im having is getting access to the variable that holds the Rectangle (named boundingBox) of the enemy. When this is in a foreach loop it works fine, as the enemy class is declared within the foreach. However, there are issues in using the foreach as it removes more than one of the enemies at once (Usually at positions 0 and 2, 1 and 3, etc...). I was wondering the best way to declare the enemy class, without it actually creating new instances of the class? Heres the code I currently have: if (keyboardState.IsKeyDown(Keys.Q) && oldKeyState.IsKeyUp(Keys.Q)) { enemyList.Add(new enemy(textureList.ElementAt(randText), new Vector2(250, 250), graphics)); } //foreach (enemy enemy in enemyList) //{ for (int i = 0; i < enemyList.Count; i++) { if (***enemy.boundingBox***.Intersects(theDefence.boxRectangle)) { enemyList[i].IsDead = true; i++; } } //} for(int j = enemyList.Count - 1; j >= 0; j--) { if(enemyList[j].IsDead) enemyList.RemoveAt(j); } (The enemy.boundingBox is the variables I can't get access too). This is a complete copy of the code (Zipped) If it helps: https://www.dropbox.com/s/ih52k4e21g98j3k/Collision%20tests.rar I managed to find the issue. Changed enemy.boundingBox to enemyList[i].boundingBox. Collision works now! Thanks for any help!

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