Search Results

Search found 29841 results on 1194 pages for 'random number generator'.

Page 21/1194 | < Previous Page | 17 18 19 20 21 22 23 24 25 26 27 28  | Next Page >

• Ubuntu: disable udev's persistent-net-generator.rules

  - by Luke404

  I'm using Ubuntu 12.04 LTS server edition and I am modifying /etc/udev/rules.d/70-persistent-net.rules to define my own mappings of ethernet interfaces to MAC addresses; that file is initially generated by rules in /lib/udev/rules.d/75-persistent-net-generator.rules at system installation time (or at the first boot, I actually don't know and it doesn't matter here). How can I be sure that my edited version will never ever be overwritten by anything? Removing the persistent-net-generator, as suggested on some websites, is not the Right Thing™ to do as told by comments in the file itself: it will be overwritten by any update of the udev package. I'm looking for a more formally correct way to disable it. Is it enough to just make sure that /etc/udev/rules.d/70-persistent-net.rules does exist? Maybe there are other events that could trigger its regeneration? (eg. adding or removing ethernet interfaces to the system?)

  Read the article

• [PHP] md5(uniqid) makes sense for random unique tokens?

  - by Exception e

  I want to create a token generator that generates tokens that cannot be guessed by the user and that are still unique (to be used for password resets and confirmation codes). I often see this code; does it make sense? md5(uniqid(rand(), true)); According to a comment uniqid($prefix, $moreEntopy = true) yields first 8 hex chars = Unixtime, last 5 hex chars = microseconds. I don't know how the $prefix-parameter is handled.. So if you don't set the $moreEntopy flag to true, it gives a predictable outcome. QUESTION: But if we use uniqid with $moreEntopy, what does hashing it with md5 buy us? Is it better than: md5(mt_rand())

  Read the article

• Shuffle tiles position in the beginning of the game XNA Csharp

  - by GalneGunnar

  Im trying to create a puzzlegame where you move tiles to certain positions to make a whole image. I need help with randomizing the tiles startposition so that they don't create the whole image at the beginning. There is also something wrong with my offset, that's why it's set to (0,0). I know my code is not good, but Im just starting to learn :] Thanks in advance My Game1 class: { public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D PictureTexture; Texture2D FrameTexture; // Offset för bildgraff Vector2 Offset = new Vector2(0,0); //skapar en array som ska hålla delar av den stora bilden Square[,] squareArray = new Square[4, 4]; // Random randomeraBilder = new Random(); //Width och Height för bilden int pictureHeight = 95; int pictureWidth = 144; Random randomera = new Random(); int index = 0; MouseState oldMouseState; int WindowHeight; int WindowWidth; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; //scalar Window till 800x 600y graphics.PreferredBackBufferWidth = 800; graphics.PreferredBackBufferHeight = 600; graphics.ApplyChanges(); } protected override void Initialize() { IsMouseVisible = true; base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); PictureTexture = Content.Load<Texture2D>(@"Images/bildgraff"); FrameTexture = Content.Load<Texture2D>(@"Images/framer"); //Laddar in varje liten bild av den stora bilden i en array for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { Vector2 position = new Vector2(x * pictureWidth, y * pictureHeight); position = position + Offset; Rectangle square = new Rectangle(x * pictureWidth, y * pictureHeight, pictureWidth, pictureHeight); Square frame = new Square(position, PictureTexture, square, Offset, index); squareArray[x, y] = frame; index++; } } } protected override void UnloadContent() { } protected override void Update(GameTime gameTime) { if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); MouseState ms = Mouse.GetState(); if (oldMouseState.LeftButton == ButtonState.Pressed && ms.LeftButton == ButtonState.Released) { // ta reda på vilken position vi har tryckt på int col = ms.X / pictureWidth; int row = ms.Y / pictureHeight; for (int x = 0; x < squareArray.GetLength(0); x++) { for (int y = 0; y < squareArray.GetLength(1); y++) { // kollar om rutan är tom och så att indexet inte går utanför för "col" och "row" if (squareArray[x, y].index == 0 && col >= 0 && row >= 0 && col <= 3 && row <= 3) { if (squareArray[x, y].index == 0 * col) { //kollar om rutan brevid mouseclick är tom if (col > 0 && squareArray[col - 1, row].index == 0 || row > 0 && squareArray[col, row - 1].index == 0 || col < 3 && squareArray[col + 1, row].index == 0 || row < 3 && squareArray[col, row + 1].index == 0) { Square sqaure = squareArray[col, row]; Square hal = squareArray[x, y]; squareArray[x, y] = sqaure; squareArray[col, row] = hal; for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { Vector2 goalPosition = new Vector2(x * pictureWidth, y * pictureHeight); squareArray[x, y].Swap(goalPosition); } } } } } } } } //if (oldMouseState.RightButton == ButtonState.Pressed && ms.RightButton == ButtonState.Released) //{ // for (int x = 0; x < 4; x++) // { // for (int y = 0; y < 4; y++) // { // } // } //} oldMouseState = ms; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); WindowHeight = Window.ClientBounds.Height; WindowWidth = Window.ClientBounds.Width; Rectangle screenPosition = new Rectangle(0,0, WindowWidth, WindowHeight); spriteBatch.Begin(); spriteBatch.Draw(FrameTexture, screenPosition, Color.White); //Ritar ut alla brickorna förutom den som har index 0 for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { if (squareArray[x, y].index != 0) { squareArray[x, y].Draw(spriteBatch); } } } spriteBatch.End(); base.Draw(gameTime); } } } My square class: class Square { public Vector2 position; public Texture2D grafTexture; public Rectangle square; public Vector2 offset; public int index; public Square(Vector2 position, Texture2D grafTexture, Rectangle square, Vector2 offset, int index) { this.position = position; this.grafTexture = grafTexture; this.square = square; this.offset = offset; this.index = index; } public void Draw(SpriteBatch spritebatch) { spritebatch.Draw(grafTexture, position, square, Color.White); } public void RandomPosition() { } public void Swap(Vector2 Goal ) { if (Goal.X > position.X) { position.X = position.X + 144; } else if (Goal.X < position.X) { position.X = position.X - 144; } else if (Goal.Y < position.Y) { position.Y = position.Y - 95; } else if (Goal.Y > position.Y) { position.Y = position.Y + 95; } } } }

  Read the article

• Replacing “if”s with your own number system

  - by Michael Williamson

  During our second code retreat at Red Gate, the restriction for one of the sessions was disallowing the use of if statements. That includes other constructs that have the same effect, such as switch statements or loops that will only be executed zero or one times. The idea is to encourage use of polymorphism instead, and see just how far it can be used to get rid of “if”s. The main place where people struggled to get rid of numbers from their implementation of Conway’s Game of Life was the piece of code that decides whether a cell is live or dead in the next generation. For instance, for a cell that’s currently live, the code might look something like this: if (numberOfNeighbours == 2 || numberOfNeighbours == 3) { return CellState.LIVE; } else { return CellState.DEAD; } The problem is that we need to change behaviour depending on the number of neighbours each cell has, but polymorphism only allows us to switch behaviour based on the type of a value. It follows that the solution is to make different numbers have different types: public interface IConwayNumber { IConwayNumber Increment(); CellState LiveCellNextGeneration(); } public class Zero : IConwayNumber { public IConwayNumber Increment() { return new One(); } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } public class One : IConwayNumber { public IConwayNumber Increment() { return new Two(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class Two : IConwayNumber { public IConwayNumber Increment() { return new ThreeOrMore(); } public CellState LiveCellNextGeneration() { return CellState.LIVE; } } public class ThreeOrMore : IConwayNumber { public IConwayNumber Increment() { return this; } public CellState LiveCellNextGeneration() { return CellState.DEAD; } } In the code that counts the number of neighbours, we use our new number system by starting with Zero and incrementing when we find a neighbour. To choose the next state of the cell, rather than inspecting the number of neighbours, we ask the number of neighbours for the next state directly: return numberOfNeighbours.LiveCellNextGeneration(); And now we have no “if”s! If C# had double-dispatch, or if we used the visitor pattern, we could move the logic for choosing the next cell out of the number classes, which might feel a bit more natural. I suspect that reimplementing the natural numbers is still going to feel about the same amount of crazy though.

  Read the article

• How to interpret number of URL errors in Google webmaster tools

  - by user359650

  Recently Google has made some changes to Webmaster tools which are explained below: http://googlewebmastercentral.blogspot.com/2012/03/crawl-errors-next-generation.html One thing I could not find out is how to interpret the number of errors over time. At the end of February we've recently migrated our website and didn't implement redirect rules for some pages (quite a few actually). Here is what we're getting from the Crawl errors: What I don't know is if the number of errors is cumulative over time or not (i.e. if Google bots crawl your website on 2 different days and find 1 separate issue on each day, whether they will report 1 error for each day, or 1 for the 1st, and 2 for the 2nd). Based on the Crawl stats we can see that the number of requests made by Google bots doesn't increase: Therefore I believe the number of errors reported is cumulative and that an error detected on 1 day is taken into account and reported on the subsequent days until the underlying problem is fixed and the page it's crawled again (or if you manually Mark as fixed the error) because if you don't make more requests to a website, there is no way you can check new pages and old pages at the same time. Q: Am I interpreting the number of errors correctly?

  Read the article

• Connecting to named Instances Using Port Number

  - by blakmk

  I came across an interesting situation where a developer was trying to connect to a named instance using a DNS alias without specifying the instance name. Coincidently though he remembered to include the port number and miraculously it worked. So it appears that sql server accepts connections to a specific instance based on its port number. While it may not seem to particularly useful, I can imagine it could be used in the following situations: To mirror to a server with a different instance name (but same port number) To hide the complexity of instance names from end users and just rely on port number (and optionally dns alias)

  Read the article

• Linking application build number to svn revision

  - by ahenderson

  I am looking for a strategy to version an application with the following requirements. My requirements are given an exe with version number (major.minor.build-number) 1) I want to map the version to a svn source revision that made the exe 2) With the source and exe I should be able to attach and debug in vs2010 with no issue. 3) Once I check-out the source code for the exe I should be able to build the exe again with the version number without having to make any changes to a file.

  Read the article

• Phone number mask in a DataView WebPart (DVWP)

  - by PeterBrunone

  This came up today on the [sharepointdiscussions] list.  A user needed to display a read-only field in a phone number format; it's pretty simple, but it may be just what you need.Assuming your list item contains a field called "Phone Number" (with a space), the following XPath will give you a number in the classic US telephone format: <xsl:value-of select="concat('(',substring(@Phone_x0020_Number,1,3),')',substring(@Phone_x0020_Number,4,3),'-',substring(@Phone_x0020_Number,7,4))" /> If you need to mask an input, try this jQuery solution.

  Read the article

• CCTV Automatic number plate recognition and integration of data,software?.

  - by abmv

  Hi, I have a client who is looking for a solution to integrate cctv with a (any) ANPR solution that can,I assume recognize the number plate of cars and store in a database and has the ability to post this data to other backoffice applications, crm, marketing app. etc. Is there any ready software to do this ? Or your recommendations ?

  Read the article

• Libnoise producing completely random noise

  - by Doodlemeat

  I am using libnoise in C++ taken and I have some problems with getting coherent noise. I mean, the noise produced now are completely random and it doesn't look like a noise. Here's a to the image produced by my game. I am diving the map into several chunks, but I can't seem to find any problem doing that since libnoise supports tileable noise. The code can be found below. Every chunk is 8x8 tiles large. Every tile is 64x64 pixels. I am also providing a link to download the entire project. It was made in Visual Studio 2013. Download link This is the code for generating a chunk Chunk *World::loadChunk(sf::Vector2i pPosition) { sf::Vector2i chunkPos = pPosition; pPosition.x *= mChunkTileSize.x; pPosition.y *= mChunkTileSize.y; sf::FloatRect bounds(static_cast<sf::Vector2f>(pPosition), sf::Vector2f(static_cast<float>(mChunkTileSize.x), static_cast<float>(mChunkTileSize.y))); utils::NoiseMap heightMap; utils::NoiseMapBuilderPlane heightMapBuilder; heightMapBuilder.SetSourceModule(mNoiseModule); heightMapBuilder.SetDestNoiseMap(heightMap); heightMapBuilder.SetDestSize(mChunkTileSize.x, mChunkTileSize.y); heightMapBuilder.SetBounds(bounds.left, bounds.left + bounds.width - 1, bounds.top, bounds.top + bounds.height - 1); heightMapBuilder.Build(); Chunk *chunk = new Chunk(this); chunk->setPosition(chunkPos); chunk->buildChunk(&heightMap); chunk->setTexture(&mTileset); mChunks.push_back(chunk); return chunk; } This is the code for building the chunk void Chunk::buildChunk(utils::NoiseMap *pHeightMap) { // Resize the tiles space mTiles.resize(pHeightMap->GetWidth()); for (int x = 0; x < mTiles.size(); x++) { mTiles[x].resize(pHeightMap->GetHeight()); } // Set vertices type and size mVertices.setPrimitiveType(sf::Quads); mVertices.resize(pHeightMap->GetWidth() * pHeightMap->GetWidth() * 4); // Get the offset position of all tiles position sf::Vector2i tileSize = mWorld->getTileSize(); sf::Vector2i chunkSize = mWorld->getChunkSize(); sf::Vector2f offsetPositon = sf::Vector2f(mPosition); offsetPositon.x *= chunkSize.x; offsetPositon.y *= chunkSize.y; // Build tiles for (int x = 0; x < mTiles.size(); x++) { for (int y = 0; y < mTiles[x].size(); y++) { // Sometimes libnoise can return a value over 1.0, better be sure to cap the top and bottom.. float heightValue = pHeightMap->GetValue(x, y); if (heightValue > 1.f) heightValue = 1.f; if (heightValue < -1.f) heightValue = -1.f; // Instantiate a new Tile object with the noise value, this doesn't do anything yet.. mTiles[x][y] = new Tile(this, pHeightMap->GetValue(x, y)); // Get a pointer to the current tile's quad sf::Vertex *quad = &mVertices[(y + x * pHeightMap->GetWidth()) * 4]; quad[0].position = sf::Vector2f(offsetPositon.x + x * tileSize.x, offsetPositon.y + y * tileSize.y); quad[1].position = sf::Vector2f(offsetPositon.x + (x + 1) * tileSize.x, offsetPositon.y + y * tileSize.y); quad[2].position = sf::Vector2f(offsetPositon.x + (x + 1) * tileSize.x, offsetPositon.y + (y + 1) * tileSize.y); quad[3].position = sf::Vector2f(offsetPositon.x + x * tileSize.x, offsetPositon.y + (y + 1) * tileSize.y); // find out which type of tile to render, atm only air or stone TileStop *tilestop = mWorld->getTileStopAt(heightValue); sf::Vector2i texturePos = tilestop->getTexturePosition(); // define its 4 texture coordinates quad[0].texCoords = sf::Vector2f(texturePos.x, texturePos.y); quad[1].texCoords = sf::Vector2f(texturePos.x + 64, texturePos.y); quad[2].texCoords = sf::Vector2f(texturePos.x + 64, texturePos.y + 64); quad[3].texCoords = sf::Vector2f(texturePos.x, texturePos.y + 64); } } } All the code that uses libnoise in some way are World.cpp, World.h and Chunk.cpp, Chunk.h in the project.

  Read the article

• What is going on with the "return fibonacci( number-1 ) + fibonacci( number-2 )"?

  - by user1478598

  I have problem understanding what the return fibonacci( number-1 ) + fibonacci( number-2 ) does in the following program: import sys def fibonacci( number ): if( number <= 2 ): return 1 else: return fibonacci( number-1 ) + fibonacci( number-2 ) The problem is that I can't imagine how this line works: return fibonacci( number-1 ) + fibonacci( number-2 ) Does the both of the "fibonacci( number-1 )" and "fibonacci( number-2 )" being processed at the same time? or the "fibonacci( number-1 )" is the first to be processed and then the second one? I only see that processing both of them would eventually return '1' so the last result I expect to see it is a '1 + 1' = '2' I would appreciate a lot, If someone can elaborately explain the process of its calculation. I think this is a very newb question but I can't really get a picture of its process.

  Read the article

• Looking for a clear and concise web page explaining why lower bits of random numbers are usually not

  - by Hamish Grubijan

  I am putting together an internal "every developer should know" wiki page. I saw many discussions regarding rand() % N, but not a single web page that explains it all. For instance, I am curious if this problem is only C- and Linux-specific, or if it also applies to Windows, C++,. Java, .Net, Python, Perl. Please help me get to the bottom of this. Also, just how non-random do the numbers get? Thank you!

  Read the article

• MySQL Query to receive random combinations from two tables.

  - by Michael

  Alright, here is my issue, I have two tables, one named firstnames and the other named lastnames. What I am trying to do here is to find 100 of the possible combinations from these names for test data. The firstnames table has 5494 entries in a single column, and the lastnames table has 88799 entries in a single column. The only query that I have been able to come up with that has some results is: select * from (select * from firstnames order by rand()) f LEFT JOIN (select * from lastnames order by rand()) l on 1=1 limit 10; The problem with this code is that it selects 1 firstname and gives every lastname that could go with it. While this is plausible, I will have to set the limit to 500000000 in order to get all the combinations possible without having only 20 first names(and I'd rather not kill my server). However, I only need 100 random generations of entries for test data, and I will not be able to get that with this code. Can anyone please give me any advice?

  Read the article

• Determining cause of random latency and loading issues

  - by Sherwin Flight

  I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of CSS and JS files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well.

  Read the article

• Determining cause of random latency/loading issues

  - by Sherwin Flight

  I'm not sure exactly what details to post in regards to my issue, because I'm not sure what is relevant. Prior to the end of September my websites all loaded quickly, in almost all cases. Loading time wasn't usually more than a few seconds. However, since the end of September I noticed a big increase in page loading times. In some cases pages were taking 30 seconds or more to load. I do have a remote monitoring service monitoring some of the sites as well, and the image below shows the response times over the past month. The response times shown at the beginning of this graph were what the usual response times were prior to this issue occurring. You can see that there has been a significant increase in response times from the beginning to the end of this graph. The thing is, the problem is not happening 100% of the time. If I click through the site, or even just keep refreshing the page, about 25% of the time the pages load quickly, the remaining 75% of the time they load slowly. Sometimes the pages take so long to load that they time out, and don't load at all. I have contacted my hosting provider, and they said things at their end was fine. I don't believe the problem is my home internet provider, because all other websites load without a problem. The server is located in Texas, USA. This also raises another interesting point. My remote monitor checks my site from two locations, California, USA, and London, England. As you can see in the chart below the response time is actually shorter when checked from London, which doesn't seem to make sense, since the server is physically closer to the California monitoring location. I would have expected the London monitoring location to have higher response times since they are physically farther away. I should also point out that in some traceroute test I've done it seem like the first connection to the server seems to take the longest, then after that the rest of the page loads quickly. Below is a little chart showing the times for the first connection to the server. So, what could be causing this problem, and what steps can I take to resolve it or at least narrow down the problem? Sending the request to the server was very quick, and receiving the reply back seems pretty quick, but the WAIT time is really long. So it connects, sends the request, but then waits close to 30 seconds before it starts receiving data back. I am also aware that there are things I can do to speed up page loading times, like reducing the number of css/js files used on a page, compressing images, etc. This is not really what the source of the problem is though, because nothing has really changed on the site since before the problem started, and other sites on the same server are loading slowly as well. Any help or advice is much appreciated.

  Read the article

• PHP rand function (or not so rand)

  - by Badr Hari

  I was testing PHP rand function to write on a image. Of course the output shows that it's not so random. The code I used: <?php header('Content-Type: image/png'); $lenght = 512; $im = imagecreatetruecolor($lenght, $lenght); $blue = imagecolorallocate($im, 0, 255, 255); for ($y = 0; $y < $lenght; $y++) { for ($x = 0; $x < $lenght; $x++) { if (rand(0,1) == 0) { imagesetpixel($im, $x, $y, $blue); } } } imagepng($im); imagedestroy($im); ?> My question is, if I use image width/lenght (variable $lenght in this example) number like 512, 256 or 1024, it is very clear that it's not so random. When I change the variable to 513 for an example, it is so much harder for human eye to detect it. Why is that? What is so special about these numbers? 512: 513: Edit: I'm running xampp on Windows to test it.

  Read the article

• Using a permutation table for simplex noise without storing it

  - by J. C. Leitão

  Generating Simplex noise requires a permutation table for randomisation (e.g. see this question or this example). In some applications, we need to persist the state of the permutation table. This can be done by creating the table, e.g. using def permutation_table(seed): table_size = 2**10 # arbitrary for this question l = range(1, table_size + 1) random.seed(seed) # ensures the same shuffle for a given seed random.shuffle(l) return l + l # see shared link why l + l; is a detail and storing it. Can we avoid storing the full table by generating the required elements every time they are required? Specifically, currently I store the table and call it using table[i] (table is a list). Can I avoid storing it by having a function that computes the element i, e.g. get_table_element(seed, i). I'm aware that cryptography already solved this problem using block cyphers, however, I found it too complex to go deep and implement a block cypher. Does anyone knows a simple implementation of a block cypher to this problem?

  Read the article

• How to generate and encode (for use in GA), random, strict, binary rooted trees with N leaves?

  - by Peter Simon

  First, I am an engineer, not a computer scientist, so I apologize in advance for any misuse of nomenclature and general ignorance of CS background. Here is the motivational background for my question: I am contemplating writing a genetic algorithm optimizer to aid in designing a power divider network (also called a beam forming network, or BFN for short). The BFN is intended to distribute power to each of N radiating elements in an array of antennas. The fraction of the total input power to be delivered to each radiating element has been specified. Topologically speaking, a BFN is a strictly binary, rooted tree. Each of the (N-1) interior nodes of the tree represents the input port of an unequal, binary power splitter. The N leaves of the tree are the power divider outputs. Given a particular power divider topology, one is still free to map the power divider outputs to the array inputs in an arbitrary order. There are N! such permutations of the outputs. There are several considerations in choosing the desired ordering: 1) The power ratio for each binary coupler should be within a specified range of values. 2) The ordering should be chosen to simplify the mechanical routing of the transmission lines connecting the power divider. The number of ouputs N of the BFN may range from, say, 6 to 22. I have already written a genetic algorithm optimizer that, given a particular BFN topology and desired array input power distribution, will search through the N! permutations of the BFN outputs to generate a design with compliant power ratios and good mechanical routing. I would now like to generalize my program to automatically generate and search through the space of possible BFN topologies. As I understand it, for N outputs (leaves of the binary tree), there are $C_{N-1}$ different topologies that can be constructed, where $C_N$ is the Catalan number. I would like to know how to encode an arbitrary tree having N leaves in a way that is consistent with a chromosomal description for use in a genetic algorithm. Also associated with this is the need to generate random instances for filling the initial population, and to implement crossover and mutations operators for this type of chromosome. Any suggestions will be welcome. Please minimize the amount of CS lingo in your reply, since I am not likely to be acquainted with it. Thanks in advance, Peter

  Read the article

• How to generate a random unique string with more than 2^30 combination. I also wanted to reverse the process. Is this possible?

  - by Yusuf S

  I have a string which contains 3 elements: a 3 digit code (example: SIN, ABD, SMS, etc) a 1 digit code type (example: 1, 2, 3, etc) a 3 digit number (example: 500, 123, 345) Example string: SIN1500, ABD2123, SMS3345, etc.. I wanted to generate a UNIQUE 10 digit alphanumeric and case sensitive string (only 0-9/a-z/A-Z is allowed), with more than 2^30 (about 1 billion) unique combination per string supplied. The generated code must have a particular algorithm so that I can reverse the process. For example: public static void main(String[] args) { String test = "ABD2123"; String result = generateData(test); System.out.println(generateOutput(test)); //for example, the output of this is: 1jS8g4GDn0 System.out.println(generateOutput(result)); //the output of this will be ABD2123 (the original string supplied) } What I wanted to ask is is there any ideas/examples/libraries in java that can do this? Or at least any hint on what keyword should I put on Google? I tried googling using the keyword java checksum, rng, security, random number, etc and also tried looking at some random number solution (java SecureRandom, xorshift RNG, java.util.zip's checksum, etc) but I can't seem to find one? Thanks! EDIT: My use case for this program is to generate some kind of unique voucher number to be used by specific customers. The string supplied will contains 3 digit code for company ID, 1 digit code for voucher type, and a 3 digit number for the voucher nominal. I also tried adding 3 random alphanumeric (so the final digit is 7 + 3 digit = 10 digit). This is what I've done so far, but the result is not very good (only about 100 thousand combination): public static String in ="somerandomstrings"; public static String out="someotherrandomstrings"; public static String encrypt(String kata) throws Exception { String result=""; String ina=in; String outa=out; Random ran = new Random(); Integer modulus=in.length(); Integer offset= ((Integer.parseInt(Utils.convertDateToString(new Date(), "SS")))+ran.nextInt(60))/2%modulus; result=ina.substring(offset, offset+1); ina=ina+ina; ina=ina.substring(offset, offset+modulus); result=result+translate(kata, ina, outa); return result; } EDIT: I'm sorry I forgot to put the "translate" function : public static String translate(String kata,String seq1, String seq2){ String result=""; if(kata!=null&seq1!=null&seq2!=null){ String[] a=kata.split(""); for (int j = 1; j < a.length; j++) { String b=a[j]; String[]seq1split=seq1.split(""); String[]seq2split=seq2.split(""); int hint=seq1.indexOf(b)+1; String sq=""; if(seq1split.length>hint) sq=seq1split[hint]; String sq1=""; if(seq2split.length>hint) sq1=seq2split[hint]; b=b.replace(sq, sq1); result=result+b; } } return result; }

  Read the article

• Why is the compiler caching my "random" and NULLED variables?

  - by alex gray

  I am confounded by the fact that even using different programs (on the same machine) to run /compile, and after nilling the vaues (before and after) the function.. that NO MATTER WHAT.. I'll keep getting the SAME "random" numbers… each and every time I run it. I swear this is NOT how it's supposed to work.. I'm going to illustrate as simply as is possible… #import <Foundation/Foundation.h> int main(int argc, char *argv[]) { int rPrimitive = 0; rPrimitive = 1 + rand() % 50; NSNumber *rObject = nil; rObject = [NSNumber numberWithInt:rand() % 10]; NSLog(@"%i %@", rPrimitive, rObject); rPrimitive = 0; rObject = nil; NSLog(@"%i %@", rPrimitive, rObject); return 0; } Run it in TextMate: i686-apple-darwin11-llvm-gcc-4.2 8 9 0 (null) Run it in CodeRunner: i686-apple-darwin11-llvm-gcc-4.2 8 9 0 (null) Run it a million times, if you'd like. You can gues what it will always be. Why does this happen? Why oh why is this "how it is"?

  Read the article

• java.util.Random zero argument enquiry

  - by deerb

  I am trying to code a game following instructions contained in an OU TMA document which read: In the constructor, write code to assign a new instance of Random to ran which you should create using the Random class's zero argument constructor Will this code work? Random ran = new Random(0) ; I am a relative newbie to Java, and I don't understand exactly what the instructions mean

  Read the article

• PC powers off at random times

  - by Timo Huovinen

  Short Version After experiencing some problems with Mobo batteries my PC started to power off at random times, the power off is instant and sudden and does not restart afterwards, need help figuring out the cause. Facts: Powers off when PC is playing games Powers off when PC is idle Powers off when PC is in safe mode Powers off when PC is in BIOS Powers off when PC is booted through a Windows installation USB Replaced the motherboard battery several times Replaced the 650W PSU with a 750W PSU Replaced the RAM Swapped the RAM between slots Re-applied thermal paste to the CPU Checked if the motherboard touches the case Nothing is overclocked PC Specs PC specs: OS: Windows 7 Ultimate SP1 RAM: klingston 1333MHz 4GB stick CPU: AMD Phenom II x4 955 Mobo: Gigabyte 88GMA-UD2H rev 2.2 Motherboard battery: CR2032 3v HDD: 500GB Seagate ST3500418AS ATA Device Graphics: ATI/AMD Radeon HD 6870 Very Long version Around 10 months ago I built a brand new gaming PC. Around 6 months ago it's time setting in windows started resetting to the year 2010. I swapped the Motherboard battery for a new one of the exact same size and shape and voltage, and the problems disappeared...for around 2 weeks. Then the same problem happened again, time gets reset, I swapped the battery again, and the problem was gone for good and everything was great for about 3 months.. then another problem started happening, the PC started to power off suddenly and without warning at completely random times, sometimes the PC works for and hour, sometimes 5 minutes. So I read on the forums that it might be either the PSU or the motherboard Battery or RAM or HDD or the Graphics card or the CPU or the motherboard or the drivers or a Virus or Grounding issues, or something short circuiting, basically it can be anything... I spent some days researching, and decided to remove the possibility of a virus. I reset the CMOS, cleared all BIOS settings and reinstalled windows 7 after a full format of the HDD, but the random power off kept happening. I then disabled the restart on error option in windows and looked at the event log for error events, but they did not help me figure out the problem. Network list service depends on network location awareness the dependency group failed to start Source Kernel Power Event 41 Task Category 63 Source Disk Event ID 11 Task Category None The driver detected a controller error on device disk I took apart the PC, every little piece, re-applied some expensive thermal paste to the CPU, and double checked that none of the pieces are touching the PC case. The problem was gone, the PC no longer powered off randomly I re-attached the graphics card and all was good for 4 months... then the power off problem appeared again, but was happening at high intervals, the PC would shutdown once in 2 days on average, at random points in time, sometimes when it's idle all day long, sometimes when it's running CRYSIS 2. I checked the CPU temperature, because I know that AMD CPU's have a built in protection mechanism that switches off the PC if the CPU gets too hot, and the Temp was 50C system temp, and 45C CPU after running the PC all day long (I did not do tests to see if there are any temperature spikes, don't know how to do them) Originally the PSU that powered the PC was 650Watts and had one 4 pin cable to power the CPU, I replaced it with a new 750Watts PSU which has two 4 pin cables for the CPU, but the problem remained. I removed the graphics card and let the motherboard use the built in one, but the PC kept suddenly powering off at random times. I took apart the PC completely again, and re-applied thermal paste to the CPU, added lots of insulation, and checked for any type of short-circuit possibility again and again, but the problem remained. The problem was like that for some months. I replaced the Battery a couple of times over the time, changed lots of options in windows, and tried everything I could, but it kept powering off, so I stopped using the PC as much as I used to, just living with the random power offs from time to time, until a couple of days ago, when the power off happens almost immediately after powering on the PC. I replaced the RAM with a brand new one, but that did not help. Took apart the PC again, checked for anything anywhere that might cause it, found some small scratches on the very edge of the motherboard to the left of the PCI express x16 slot. This might cause the problem, I thought, but the scratch looks very superficial, not deep at all, and if the scratch did harm the motherboard, wouldn't it cause it to not start at all? And why did it start to power off a while ago, and then suddenly stop powering off? The scratches could not have vanished??? did chkdsk \d but it powered off when it was at 75% I removed the hard disks, the graphics card, while I fiddled with the BIOS settings, and suddenly the PC shut down while I was looking at the BIOS version. This makes me realize, it is not caused by: HDD, Windows, Drivers or the Graphics card I cleared the CMOS again, updated the BIOS from F5 to F6f beta, but that did not help, it might even seem that the PC powers off even sooner. The shutdown even happened to me while I booted through a windows 7 installation USB and was in the repair console. I removed one of the cables powering the CPU, now only one 4pin cable powers it, and it worked for 30mins after doing that, which makes me think that it's the CPU overheating, and because it gets less power, it overheats slower? The things that I am still considering: CPU overheating (does not seem to overheat, maybe false readings?) Motherboard short circuiting (faulty motherboard?) I desperately need some advice in what is faulty, is it a faulty Motherboard or an overheating CPU? or maybe something else? I have been breaking my head over this problem over a span of 6 months. I'm not sure if this is a good place to ask this question, if it is not, then tell me where I can get some experienced help. More info I have also discovered a mysterious piece that seems to have fallen out of the motherboard i119.photobucket.com/albums/o126/yurikolovsky/strangepiece.jpg What is it? Looks like each time that it powers off the datetime gets reset I also found another forum post tomshardware.co.uk/forum/… except I don't have Integrated PeripheralsUSB Keyboard Function option in BIOS :S Comments summary (asked by Random moderator) Q. tell me, if the computer restarts, is it immediately? Does it take a second and then restarts? Do you see (BSOD) or hear (PSU, short circuit) any suspicious when it happens? After reading trough it, it remains the mainboard that is faulty. – JohannesM A. Immediate power off, all the fans stop instantly, all the light turn off instantly, no sound or anything, and it remains off until I turn it back on. Thanks for the feedback, faulty motherboard is what I fear. Q. Try stress-testing the system with Prime95 and see if errors or shutdowns occur when the CPU is under full load. – speakr A. Prime95 heat stress test peaked CPU heat at 60C after 5mins, it powered off after 30mins of testing in the middle of the test with no errors, Prime95 Heat test or the stress-testing with low RAM usage (small or in-place FFTs) do not report errors while testing for 10-60 mins. The power off does not seem like it is affected by Prime95 at all Makes me wonder if it's a CPU or Motherboard issue at all. Q. I had similar random/intermittent problems with my old board. It gave one of a few different symptoms: keyboard and/or mouse would die and/or the RAM wouldn't work and/or it would shut down. It was in bad shape. One problems was that my old PSU had literally burned the connector on it (browned around the pins), another was that a broken lead inside the layers of the PCB would work sometimes if it happened to be hot or if I bent the board—by jamming a hunk of wood behind it. I managed to keep the board alive for several years, but eventually nothing I did would make it work correctly anymore. – Synetech A. I will try that as the last resort, ok? ;) Q. Have you tried a different power cord, surge protector, outlet (on a different circuit). It's worth a shot just to ensure it's not subpar wiring or a week circuit (dips in power may cause shutdown if the PSU can't pull enough juice from the wall). – Kyle A. yes, I attached the PC to an entirely different outlet on a different circuit and the problem persists. After connecting it to a different outlet after starting the PC it gave me 3 long beeps and 1 short one, then the PC immediately proceeded to boot up normally. Q. Re-check your mainboard manual and all PSU connections to your mainboard to be sure that nothing is missing (e.g. 12V ATX 4-pin/6-pin connector). If you can provoke shutdowns with Prime95, then consider buying new hardware -- a stable system should run Prime95 for 24h without any errors. Prime95 mentions errors in the log when they occur and gives a summary after the stress test was stopped manually (e.g. "0 errors, 0 warnings", if all is fine) – speakr A. Re-checked, there are no more PSU connectors that I can physically connect, except the one ATX 4-pin (there are 2 that power the CPU) that I disconnected on purpose, I have reconnected it but the problem persists. Q. With one PC I had a short curcuit. The power button on the front plate had its cables soldered, but not isolated, and the contacts were very close to the metal case. A heavier touch was enough to cause a shutdown. The PC's vibration could be enough – ott-- A. yes, it seems to switch off with even the lightest touch, I switched on the PC, then pulled out the front panel power cable that connects to the motherboard so the power button does not work anymore, after 5 mins of working like that, with the power button completely disconnected, just sitting idle, the PC powered off again, I don't think it's the power button. Q. I wonder if you dare to operate components without the case, that is remove motherboard, power, disk ( just put the motherboard on a wooden desk). Don't bend the adapters when running like that. – ott-- A. yes, I do dare to do that, but only tomorrow, too tired/late right now.

  Read the article

• selected option not clearing from memory android

  - by user2980560

  I have a small random number spinner that when you click gives a random number. I am having two problems. The first is when the main activity loads it displays a random number on the screen without the random number spinner being clicked. I am unsure what to set to false to keep it from opening with the main activity. The second problem is that when you select an option from the spinner it does not clear. Meaning that If you click on option D6 or D20 then you can not click on the same option again until selecting the other option first. Essentially the selection does not clear out of memory after the random number is selected. Here is the random number code public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { Random rand = new Random(); int roll; // An item was selected. if (spinner1.getSelectedItemPosition()==0) { roll = rand.nextInt(6)+1; } else { roll = rand.nextInt(20)+1; } // Put the result into a string. String text = "You rolled a " + roll; // Build a dialog box and with the result string and a single button AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setMessage(text).setCancelable(false) .setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { // do things when the user clicks ok. } }); AlertDialog alert = builder.create(); // Show the dialog box. alert.show(); }

  Read the article

• A python random function acts differently when assigned to a list or called directly...

  - by Dror Hilman

  I have a python function that randomize a dictionary representing a position specific scoring matrix. for example: mat = { 'A' : [ 0.53, 0.66, 0.67, 0.05, 0.01, 0.86, 0.03, 0.97, 0.33, 0.41, 0.26 ] 'C' : [ 0.14, 0.04, 0.13, 0.92, 0.99, 0.04, 0.94, 0.00, 0.07, 0.23, 0.35 ] 'T' : [ 0.25, 0.07, 0.01, 0.01, 0.00, 0.04, 0.00, 0.03, 0.06, 0.12, 0.14 ] 'G' : [ 0.08, 0.23, 0.20, 0.02, 0.00, 0.06, 0.04, 0.00, 0.54, 0.24, 0.25 ] } The scambling function: def scramble_matrix(matrix, iterations): mat_len = len(matrix["A"]) pos1 = pos2 = 0 for count in range(iterations): pos1,pos2 = random.sample(range(mat_len), 2) #suffle the matrix: for nuc in matrix.keys(): matrix[nuc][pos1],matrix[nuc][pos2] = matrix[nuc][pos2],matrix[nuc][pos1] return matrix def print_matrix(matrix): for nuc in matrix.keys(): print nuc+"[", for count in matrix[nuc]: print "%.2f"%count, print "]" now to the problem... When I try to scramble a matrix directly, It's works fine: print_matrix(mat) print "" print_matrix(scramble_matrix(mat,10)) gives: A[ 0.53 0.66 0.67 0.05 0.01 0.86 0.03 0.97 0.33 0.41 0.26 ] C[ 0.14 0.04 0.13 0.92 0.99 0.04 0.94 0.00 0.07 0.23 0.35 ] T[ 0.25 0.07 0.01 0.01 0.00 0.04 0.00 0.03 0.06 0.12 0.14 ] G[ 0.08 0.23 0.20 0.02 0.00 0.06 0.04 0.00 0.54 0.24 0.25 ] A[ 0.41 0.97 0.03 0.86 0.53 0.66 0.33.05 0.67 0.26 0.01 ] C[ 0.23 0.00 0.94 0.04 0.14 0.04 0.07 0.92 0.13 0.35 0.99 ] T[ 0.12 0.03 0.00 0.04 0.25 0.07 0.06 0.01 0.01 0.14 0.00 ] G[ 0.24 0.00 0.04 0.06 0.08 0.23 0.54 0.02 0.20 0.25 0.00 ] but when I try to assign this scrambling to a list , it does not work!!! ... print_matrix(mat) s=[] for x in range(3): s.append(scramble_matrix(mat,10)) for matrix in s: print "" print_matrix(matrix) result: A[ 0.53 0.66 0.67 0.05 0.01 0.86 0.03 0.97 0.33 0.41 0.26 ] C[ 0.14 0.04 0.13 0.92 0.99 0.04 0.94 0.00 0.07 0.23 0.35 ] T[ 0.25 0.07 0.01 0.01 0.00 0.04 0.00 0.03 0.06 0.12 0.14 ] G[ 0.08 0.23 0.20 0.02 0.00 0.06 0.04 0.00 0.54 0.24 0.25 ] A[ 0.01 0.66 0.97 0.67 0.03 0.05 0.33 0.53 0.26 0.41 0.86 ] C[ 0.99 0.04 0.00 0.13 0.94 0.92 0.07 0.14 0.35 0.23 0.04 ] T[ 0.00 0.07 0.03 0.01 0.00 0.01 0.06 0.25 0.14 0.12 0.04 ] G[ 0.00 0.23 0.00 0.20 0.04 0.02 0.54 0.08 0.25 0.24 0.06 ] A[ 0.01 0.66 0.97 0.67 0.03 0.05 0.33 0.53 0.26 0.41 0.86 ] C[ 0.99 0.04 0.00 0.13 0.94 0.92 0.07 0.14 0.35 0.23 0.04 ] T[ 0.00 0.07 0.03 0.01 0.00 0.01 0.06 0.25 0.14 0.12 0.04 ] G[ 0.00 0.23 0.00 0.20 0.04 0.02 0.54 0.08 0.25 0.24 0.06 ] A[ 0.01 0.66 0.97 0.67 0.03 0.05 0.33 0.53 0.26 0.41 0.86 ] C[ 0.99 0.04 0.00 0.13 0.94 0.92 0.07 0.14 0.35 0.23 0.04 ] T[ 0.00 0.07 0.03 0.01 0.00 0.01 0.06 0.25 0.14 0.12 0.04 ] G[ 0.00 0.23 0.00 0.20 0.04 0.02 0.54 0.08 0.25 0.24 0.06 ] What is the problem??? Why the scrambling do not work after the first time, and all the list filled with the same matrix?!

  Read the article

• How do I randomly generate a top-down 2D level with separate sections and is infinite?

  - by Bagofsheep

  I've read many other questions/answers about random level generation but most of them deal with either randomly/proceduraly generating 2D levels viewed from the side or 3D levels. What I'm trying to achieve is sort of like you were looking straight down on a Minecraft map. There is no height, but the borders of each "biome" or "section" of the map are random and varied. I already have basic code that can generate a perfectly square level with the same tileset (randomly picking segments from the tileset image), but I've encountered a major issue for wanting the level to be infinite: Beyond a certain point, the tiles' positions become negative on one or both of the axis. The code I use to only draw tiles the player can see relies on taking the tiles position and converting it to the index number that represents it in the array. As you well know, arrays cannot have a negative index. Here is some of my code: This generates the square (or rectangle) of tiles: //Scale is in tiles public void Generate(int sX, int sY) { scaleX = sX; scaleY = sY; for (int y = 0; y <= scaleY; y++) { tiles.Add(new List<Tile>()); for (int x = 0; x <= scaleX; x++) { tiles[tiles.Count - 1].Add(tileset.randomTile(x * tileset.TileSize, y * tileset.TileSize)); } } } Before I changed the code after realizing an array index couldn't be negative my for loops looked something like this to center the map around (0, 0): for (int y = -scaleY / 2; y <= scaleY / 2; y++) for (int x = -scaleX / 2; x <= scaleX / 2; x++) Here is the code that draws the tiles: int startX = (int)Math.Floor((player.Position.X - (graphics.Viewport.Width) - tileset.TileSize) / tileset.TileSize); int endX = (int)Math.Ceiling((player.Position.X + (graphics.Viewport.Width) + tileset.TileSize) / tileset.TileSize); int startY = (int)Math.Floor((player.Position.Y - (graphics.Viewport.Height) - tileset.TileSize) / tileset.TileSize); int endY = (int)Math.Ceiling((player.Position.Y + (graphics.Viewport.Height) + tileset.TileSize) / tileset.TileSize); for (int y = startY; y < endY; y++) { for (int x = startX; x < endX; x++) { if (x >= 0 && y >= 0 && x <= scaleX && y <= scaleY) tiles[y][x].Draw(spriteBatch); } } So to summarize what I'm asking: First, how do I randomly generate a top-down 2D map with different sections (not chunks per se, but areas with different tile sets) and second, how do I get past this negative array index issue?

  Read the article

< Previous Page | 17 18 19 20 21 22 23 24 25 26 27 28  | Next Page >