Search Results

Search found 4176 results on 168 pages for 'graph algorithms'.

Page 38/168 | < Previous Page | 34 35 36 37 38 39 40 41 42 43 44 45 | Next Page >

Graph database for .NET

- by Antonello

I've been designing an application, based on .NET/Mono framework, which should make an heavy use of the shortest-path in a graph theories and I would like to use a native solution to traverse the nodes of the graph, instead of implementing surrogate solutions which would be hardly maintainable and would massively affect performances. I've found an application which would be perfect for my scope: neo4j. Unfortunately, this application is purely written in Java code and it's not portable to .NET, because of the massive differences between the two architectures. Is anyone out there knows if is it there any port of neo4j or a similar solution for .NET?

Read the article
change attributes of SVG graph without refresh

- by Mike Hudak

Hello, I have a simple SVG graph generated by GraphViz: <?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">   <svg width="138pt" height="168pt" viewBox="0.00 0.00 138.00 168.00" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <g id="graph1" class="graph" transform="scale(1 1) rotate(0) translate(4 164)"> <title>G</title> <polygon fill="white" stroke="white" points="-4,5 -4,-164 135,-164 135,5 -4,5"/>  <g id="node1" class="node"><title>Node1</title> <a xlink:href="http://localhost/viz/applet.php" xlink:title="Internet"> <image xlink:href="images/cloud.png" width="130px" height="77px" preserveAspectRatio="xMinYMin meet" x="0" y="-159.5"/> <text text-anchor="middle" x="65" y="-116.4" font-family="Times New Roman,serif" font-size="14.00">'.$Internet.'</text> </a> </g>  <g id="node2" class="node"><title>Node2</title> <a xlink:href="http://localhost/viz/applet.php"> <image xlink:href="images/file server.png" width="44px" height="45px" preserveAspectRatio="xMinYMin meet" x="43" y="-45.5"/> </a> </g>  <g id="edge2" class="edge"><title>Node1->Node2</title> <a xlink:title="Bandwidth: 1544kbps
Using link: 12%
VOIP calls: 4
Packet rate: 10000
Packet loss: 2"> <path fill="none" stroke="black" d="M65,-82.2678C65,-73.5404 65,-64.358 65,-55.8964"/> <polygon fill="black" stroke="black" points="68.5001,-55.6524 65,-45.6524 61.5001,-55.6525 68.5001,-55.6524"/> </a> </g> </g> </svg> I want to change some atributes: for example " VOIP calls: 4 " -changing "4" to value from Database(LDAP) without refreshing whole SVG graph <a xlink:title="Bandwidth: 1544kbps
Using link: 12%
VOIP calls: 4
Packet rate: 10000
Packet loss: 2"> Thank you for your answers

Read the article
Core-Plot graph in a UIViewController

- by Kenneth

Hi guys, im trying to put a Coreplot graph in a UIView. Some questions, should i do it in XIB? or should i do it programmically ? If so how should i write the codes? etc. I actually have two Classes. one called GraphView which is supposed to hold the Coreplot graph. Another called CorePlotViewController. Thx for looking guys.

Read the article
Travelling Salesman Problem Constraint Representation

- by alex25

Hey! I read a couple of articles and sample code about how to solve TSP with Genetic Algorithms and Ant Colony Optimization etc. But everything I found didn't include time (window) constraints, eg. "I have to be at customer x before 12am)" and assumed symmetry. Can somebody point me into the direction of some sample code or articles that explain how I can add constraints to TSP and how I can represent those in code. Thanks!

Read the article
PHP given a series of arbitrary numbers, how can I choose a logical max value on a line graph?

- by stormist

I am constructing a line graph in PHP. I was setting the max value of the line graph to the max value of my collection of items, but this ended up making the graph less readable you are unable to view the highest line on the graph as it intersects with the top of it. So what I need is basically a formula to take a set of numbers and calculate what the logical max value of on the line graph should be.. so some examples 3500 250 10049 45394 434 312 Max value on line graph should probably be 50000 493 412 194 783 457 344 max value on line graph would ideally be 1000 545 649 6854 5485 11545 In this case, 12000 makes sense as max value So something as simple as rounding upward to the nearest thousandth might work but I'd need it to progressively increase as the numbers got bigger. (50000 instead of 46,000 in first example) The maximum these numbers will ever be is about a million. Any recommendations would be greatly appreciated, thank you.

Read the article
Howto Plot "Reverse" Cumulative Frequency Graph With ECDF

- by neversaint

I have no problem plotting the following cumulative frequency graph plot like this. library(Hmisc) pre.test <- rnorm(100,50,10) post.test <- rnorm(100,55,10) x <- c(pre.test, post.test) g <- c(rep('Pre',length(pre.test)),rep('Post',length(post.test))) Ecdf(x, group=g, what="f", xlab='Test Results', label.curves=list(keys=1:2)) But I want to show the graph in forms of the "reverse" cumulative frequency of values x ? (i.e. something equivalent to what="1-f"). Is there a way to do it? Other suggestions in R other than using Hmisc are also very much welcomed.

Read the article
Graph Tour with Uniform Cost Search in Java

- by user324817

Hi. I'm new to this site, so hopefully you guys don't mind helping a nub. Anyway, I've been asked to write code to find the shortest cost of a graph tour on a particular graph, whose details are read in from file. The graph is shown below: http://img339.imageshack.us/img339/8907/graphr.jpg This is for an Artificial Intelligence class, so I'm expected to use a decent enough search method (brute force has been allowed, but not for full marks). I've been reading, and I think that what I'm looking for is an A* search with constant heuristic value, which I believe is a uniform cost search. I'm having trouble wrapping my head around how to apply this in Java. Basically, here's what I have: Vertex class - ArrayList<Edge> adjacencies; String name; int costToThis; Edge class - final Vertex target; public final int weight; Now at the moment, I'm struggling to work out how to apply the uniform cost notion to my desired goal path. Basically I have to start on a particular node, visit all other nodes, and end on that same node, with the lowest cost. As I understand it, I could use a PriorityQueue to store all of my travelled paths, but I can't wrap my head around how I show the goal state as the starting node with all other nodes visited. Here's what I have so far, which is pretty far off the mark: public static void visitNode(Vertex vertex) { ArrayList<Edge> firstEdges = vertex.getAdjacencies(); for(Edge e : firstEdges) { e.target.costToThis = e.weight + vertex.costToThis; queue.add(e.target); } Vertex next = queue.remove(); visitNode(next); } Initially this takes the starting node, then recursively visits the first node in the PriorityQueue (the path with the next lowest cost). My problem is basically, how do I stop my program from following a path specified in the queue if that path is at the goal state? The queue currently stores Vertex objects, but in my mind this isn't going to work as I can't store whether other vertices have been visited inside a Vertex object. Help is much appreciated! Josh

Read the article
Line graph disappears after new line is added

- by tonystinge

I am having trouble uploading a large .csv file to my HIGHCHART graph. I've been able to graph an 85KB up to 1486 lines by 9 (I) columns. Here is an example: TimeStamp Temp_1_01 Temp_1_02 Temp_2_01 Temp_2_02 Temp_3_01 Temp_3_02 Temp_4_01 Temp_4_02 5/15/2014, 3:25 408 487 63 84 67 91 63 78 5/15/2014 3:30 408 487 63 84 67 91 63 78 5/15/2014 3:35 407 489 63 84 67 91 63 78 5/15/2014 3:40 408 488 63 84 67 91 63 78 5/15/2014 3:44 408 488 63 84 67 91 63 78 ... 5/22/2014 9:40 483 421 0 93 76 95 72 89 When I add a new line the line graph disappears. Any suggestions? Here is the javascript: $.get('Dropbox/geo/sites/GC_Room/loveland.csv', function(data) { // Split the lines var lines = data.split('\n'); var i = 0; var csvData = []; // Iterate over the lines and add categories or series $.each(lines, function(lineNo, line) { csvData[i] = line.split(','); i = i + 1; }); var columns = csvData[0]; var categories = [], series = []; for(var colIndex=0,len=columns.length; colIndex<len; colIndex++) { //first row data as series's name var seriesItem= { data:[], name:csvData[0][colIndex] }; for(var rowIndex=1,rowCnt=csvData.length; rowIndex<rowCnt; rowIndex++) { //first column data as categories, if (colIndex == 0) { categories.push(csvData[rowIndex][0]); } else if(parseFloat(csvData[rowIndex][colIndex])) // <-- here { seriesItem.data.push(parseFloat(csvData[rowIndex][colIndex])); } }; //except first column if(colIndex>0)series.push(seriesItem); } // Create the chart var chart = new Highcharts.Chart( { chart: { alignTick: false, renderTo: 'LANE_METALS', type: 'line' }, title: { text: 'Monthly Average Temperature', x: -20 //center }, subtitle: { text: 'Source: LANE METALS', x: -20 }, xAxis: { categories: categories, labels: { step: 200, text: 'Time', }, tickWidth: 0 }, yAxis: { title: { text: 'Temperature (\xB0C)' }, min: 0 }, tooltip: { formatter: function() { return '<b>'+ this.series.name +'</b><br/>'+ this.x +': '+ this.y +'\xB0C'; } }, legend: { layout: 'vertical', //backgroundColor: '#FFFFFF', //floating: true, align: 'left', //x: 100, verticalAlign: 'top', //y: 70, borderWidth: 0 }, plotOptions: { area: { turboThreshold: 0, stacking: 'normal', lineColor: '#666666', lineWidth: 1, marker: { lineWidth: 1, lineColor: '#666666' } } }, series: series }); });

Read the article
Howto plot two cumulative frequency graph together

- by neversaint

I have data that looks like this: #val Freq1 Freq2 0.000 178 202 0.001 4611 5300 0.002 99 112 0.003 26 30 0.004 17 20 0.005 15 20 0.006 11 14 0.007 11 13 0.008 13 13 ...many more lines.. Full data can be found here: http://dpaste.com/173536/plain/ What I intend to do is to have a cumulative graph with "val" as x-axis with "Freq1" & "Freq2" as y-axis, plot together in 1 graph. I have this code. But it creates two plots instead of 1. dat <- read.table("stat.txt",header=F); val<-dat$V1 freq1<-dat$V2 freq2<-dat$V3 valf1<-rep(val,freq1) valf2<-rep(val,freq2) valfreq1table<- table(valf1) valfreq2table<- table(valf2) cumfreq1=c(0,cumsum(valfreq1table)) cumfreq2=c(0,cumsum(valfreq2table)) plot(cumfreq1, ylab="CumFreq",xlab="Loglik Ratio") lines(cumfreq1) plot(cumfreq2, ylab="CumFreq",xlab="Loglik Ratio") lines(cumfreq2) What's the right way to approach this?

Read the article
Genetic Algorithms applied to Curve Fitting

- by devoured elysium

Let's imagine I have an unknown function that I want to approximate via Genetic Algorithms. For this case, I'll assume it is y = 2x. I'd have a DNA composed of 5 elements, one y for each x, from x = 0 to x = 4, in which, after a lot of trials and computation and I'd arrive near something of the form: best_adn = [ 0, 2, 4, 6, 8 ] Keep in mind I don't know beforehand if it is a linear function, a polynomial or something way more ugly, Also, my goal is not to infer from the best_adn what is the type of function, I just want those points, so I can use them later. This was just an example problem. In my case, instead of having only 5 points in the DNA, I have something like 50 or 100. What is the best approach with GA to find the best set of points? Generating a population of 100, discard the worse 20% Recombine the remaining 80%? How? Cutting them at a random point and then putting together the first part of ADN of the father with the second part of ADN of the mother? Mutation, how should I define in this kind of problem mutation? Is it worth using Elitism? Any other simple idea worth using around? Thanks

Read the article
Adapting Machine Learning Algorithms to my Problem

- by Berkay

i'm working on a project and need your ideas, advices. First of all, let me tell my problem. There is power button and some other keys of a machine and there is only one user has authentication to use this machine.There are no other authentication methods, the machine is in public area in a company. the machine is working with the combination of pressing power button and some other keys. The order of pressing keys is secret but we don't trust it, anybody can learn the password and can access the machine. i have the capability of managing the key hold time and also some other metrics to measure the time differences between the key such as horizantal or vertical key press times (differences). and also i can measure the hold time etc. These all means i have some inputs, Now i'm trying to get a user profile by analysing these inputs. My idea is to get the authenticated user to press the password n times and create a threshold or something similar to that. This method also can be said BIOMETRICS, anyone else who knows the machine button combination, can try the password but if he is out of this range can not get access it. How can i adapt these into my algorithms? where should i start ? i don't want to delve deep into machine learning, and also i can see the in my first try i can get false positive and false negative values really high, but i can manage it by changing my inputs. thanks.

Read the article
Evolutionary Algorithms: Optimal Repopulation Breakdowns

- by Brian MacKay

It's really all in the title, but here's a breakdown for anyone who is interested in Evolutionary Algorithms: In an EA, the basic premise is that you randomly generate a certain number of organisms (which are really just sets of parameters), run them against a problem, and then let the top performers survive. You then repopulate with a combination of crossbreeds of the survivors, mutations of the survivors, and also a certain number of new random organisms. Do that several thousand times, and efficient organisms arise. Some people also do things like introduce multiple "islands" of organisms, which are seperate populations that are allowed to crossbreed once in awhile. So, my question is: what are the optimal repopulation percentages? I have been keeping the top 10% performers, and repopulating with 30% crossbreeds and 30% mutations. The remaining 30% is for new organisms. I have also tried out the multiple island theory, and I'm interested in your results on that as well. It is not lost on me that this is exactly the type of problem an EA could solve. Are you aware of anyone trying that? Thanks in advance!

Read the article
Scientific Algorithms that can produce imagery, pseudocode perhaps?

- by Ross

Hello, I have a client who are based in the field of mathematics. We are developing, amongst other things, a website. I like to create a mock-up of a drawing tool that an produce some imagery in the background based on some scientific algorithms. The intention being that the may client, later, may create there own. (They use emacs for everything, great client.) I'm look for an answer of where or what to go looking for. Not code specific, pseudocode even, as we can adapt and have not yet settled on a platform. I'm afraid my mathematic stops at the power of two and some trigonometry. Appreciated if they're are any mathematics related students/academics how could enlighten me? What to search for will be accepted? Edit: To summarise/clarify, I want to draw pretty pictures (the design perspective). I want them to have some context (i.e. not just for the sake of pretty images but have some explanation available). In essence I would to create a rendering engine which we can draw the images and we set the style parameters: line, colour, etc... But to pursue this option I want to experiment myself. Thanks Ross

Read the article
State of the art Culling and Batching techniques in rendering

- by Kristian Skarseth

I'm currently working with upgrading and restructuring an OpenGL render engine. The engine is used for visualising large scenes of architectural data (buildings with interior), and the amount of objects can become rather large. As is the case with any building, there is a lot of occluded objects within walls, and you naturally only see the objects that are in the same room as you, or the exterior if you are on the outside. This leaves a large number of objects that should be occluded through occlusion culling and frustum culling. At the same time there is a lot of repetative geometry that can be batched in renderbatches, and also a lot of objects that can be rendered with instanced rendering. The way I see it, it can be difficult to combine renderbatching and culling in an optimal fashion. If you batch too many objects in the same VBO it's difficult to cull the objects on the CPU in order to skip rendering that batch. At the same time if you skip the culling on the cpu, a lot of objects will be processed by the GPU while they are not visible. If you skip batching copletely in order to more easily cull on the CPU, there will be an unwanted high amount of render calls. I have done some research into existing techniques and theories as to how these problems are solved in modern graphics, but I have not been able to find any concrete solution. An idea a colleague and me came up with was restricting batches to objects relatively close to eachother e.g all chairs in a room or within a radius of n meeters. This could be simplified and optimized through use of oct-trees. Does anyone have any pointers to techniques used for scene managment, culling, batching etc in state of the art modern graphics engines?

Read the article
Facebook Stories for Retailers

- by David Dorf

Getting people to "like" a brand is important because it opens the door to a possible B2C relationship. Once a person likes that brand, the brand can post to their newsfeed with promotions, announcements, and surveys. At least for me, I "hide" the noisy brands and just monitor the ones that keep posts under 4 times a week. I see lots of people, especially with fashion brands, comment on postings at which point the posting is seen by their network. A metric I've heard (but not verified) is that for every person that comments, ten of their friends see the original posting. That's a pretty cheap way to communicate to potential customers in a viral way. Over at mainstreet.com they compiled the a list of the top liked retailers on Facebook as of Feb 1, 2011. They are listed below: 19,414,892 Starbucks 11,302,939 Victoria's Secret 7,925,184 Zara 7,032,398 McDonald's 6,117,222 H&M 5,400,586 Taco Bell 4,665,760 Subway 4,494,849 Lacoste 4,185,570 Hollister 3,973,181 Forever 21 So I guess the public likes their fast-food and fashion. To take this to the next level, Facebook is now displaying Sponsored Stories, which I saw for the first time on my page this weekend. I found this picture at the Wall Blog that depicits Sponsored Stories very well. Over on the right-hand column of a person's page, where they see advertisements and such, Facebook will post stories involving their network of friends and their interaction with sponsored brands. Now their "likes" can suddenly become your ads. "Jessica and Philip like Starbucks. What are you waiting for?" This is another great way to take messages viral by accessing social graphs. As usual there will be a certain level of outcry from privacy advocates, but given the other more iniquitous issues, I believe this will fall by the wayside. Retailers should consider using Sponsored Stories to increase their Likes, and thus increase their voice in the social world.

Read the article
Better data structure for a game like Bubble Witch

- by CrociDB

I'm implementing a bubble-witch-like game (http://www.king.com/games/puzzle-games/bubble-witch/), and I was thinking on what's the better way to store the "bubbles" and to work with. I thought of using graphs, but that might be too complex for a trivial thing. Thought of a matrix, just like a tile map, but that might get too 'workaroundy'. I don't know. I'll be doing in Flash/AS3, though. Thanks. :)

Read the article
Engine Rendering pipeline : Making shaders generic

- by fakhir

I am trying to make a 2D game engine using OpenGL ES 2.0 (iOS for now). I've written Application layer in Objective C and a separate self contained RendererGLES20 in C++. No GL specific call is made outside the renderer. It is working perfectly. But I have some design issues when using shaders. Each shader has its own unique attributes and uniforms that need to be set just before the main draw call (glDrawArrays in this case). For instance, in order to draw some geometry I would do: void RendererGLES20::render(Model * model) { // Set a bunch of uniforms glUniformMatrix4fv(.......); // Enable specific attributes, can be many glEnableVertexAttribArray(......); // Set a bunch of vertex attribute pointers: glVertexAttribPointer(positionSlot, 2, GL_FLOAT, GL_FALSE, stride, m->pCoords); // Now actually Draw the geometry glDrawArrays(GL_TRIANGLES, 0, m->vertexCount); // After drawing, disable any vertex attributes: glDisableVertexAttribArray(.......); } As you can see this code is extremely rigid. If I were to use another shader, say ripple effect, i would be needing to pass extra uniforms, vertex attribs etc. In other words I would have to change the RendererGLES20 render source code just to incorporate the new shader. Is there any way to make the shader object totally generic? Like What if I just want to change the shader object and not worry about game source re-compiling? Any way to make the renderer agnostic of uniforms and attributes etc?. Even though we need to pass data to uniforms, what is the best place to do that? Model class? Is the model class aware of shader specific uniforms and attributes? Following shows Actor class: class Actor : public ISceneNode { ModelController * model; AIController * AI; }; Model controller class: class ModelController { class IShader * shader; int textureId; vec4 tint; float alpha; struct Vertex * vertexArray; }; Shader class just contains the shader object, compiling and linking sub-routines etc. In Game Logic class I am actually rendering the object: void GameLogic::update(float dt) { IRenderer * renderer = g_application->GetRenderer(); Actor * a = GetActor(id); renderer->render(a->model); } Please note that even though Actor extends ISceneNode, I haven't started implementing SceneGraph yet. I will do that as soon as I resolve this issue. Any ideas how to improve this? Related design patterns etc? Thank you for reading the question.

Read the article
OpenGraph tags and HTML5 validity

- by netmano

I have a HTML5 based page, and I inculded the OpenGraph tags according to it's documentation. Also I checked with Facebook Debug, and it can parse the metadata. But when I use W3C Validator, it reports the OG tags as error: Attribute content not allowed on element meta at this point. <meta property="fb:admins" content="...." /> Attribute content not allowed on element meta at this point. <meta property="og:url" content="http://www...."> They are all in the <head>. I would need my page be "valid" HTML5 and OG tags, as well. Could you help me giving a hint how can it be achieved? UPDATE: The name version also invalid: <meta name='fb:admins' content=''>

Read the article
How to avoid game objects accidentally deleting themselves in C++

- by Tom Dalling

Let's say my game has a monster that can kamikaze explode on the player. Let's pick a name for this monster at random: a Creeper. So, the Creeper class has a method that looks something like this: void Creeper::kamikaze() { EventSystem::postEvent(ENTITY_DEATH, this); Explosion* e = new Explosion; e->setLocation(this->location()); this->world->addEntity(e); } The events are not queued, they get dispatched immediately. This causes the Creeper object to get deleted somewhere inside the call to postEvent. Something like this: void World::handleEvent(int type, void* context) { if(type == ENTITY_DEATH){ Entity* ent = dynamic_cast<Entity*>(context); removeEntity(ent); delete ent; } } Because the Creeper object gets deleted while the kamikaze method is still running, it will crash when it tries to access this->location(). One solution is to queue the events into a buffer and dispatch them later. Is that the common solution in C++ games? It feels like a bit of a hack, but that might just be because of my experience with other languages with different memory management practices. In C++, is there a better general solution to this problem where an object accidentally deletes itself from inside one of its methods?

Read the article
Nested Entities and calculation on leaf entity property - SQL or NoSQL approach

- by Chandu

I am working on a hobby project called Menu/Recipe Management. This is how my entities and their relations look like. A Nutrient has properties Code and Value An Ingredient has a collection of Nutrients A Recipe has a Collection of Ingredients and occasionally can have a collection of other recipes A Meal has a Collection of Recipes and Ingredients A Menu has a Collection of Meals The relations can be depicted as In one of the pages, for a selected menu I need to display the effective nutrients information calculated based on its constituents (Meals, Recipes, Ingredients and the corresponding nutrients). As of now am using SQL Server to store the data and I am navigating the chain from my C# code, starting from each meal of the menu and then aggregating the nutrient values. I think this is not an efficient way as this calculation is being done every time the page is requested and the constituents change occasionally. I was thinking about a having a background service that maintains a table called MenuNutrients ({MenuId, NutrientId, Value}) and will populate/update this table with the effective nutrients when any of the component (Meal, Recipe, Ingredient) changes. I feel that a GraphDB would be a good fit for this requirement, but my exposure to NoSQL is limited. I want to know what are the alternative solutions/approaches to this requirement of displaying the nutrients of a given menu. Hope my description of the scenario is clear.

Read the article
Legal responsibility of public posts

- by Murdock

Given a public site with no logins: I let people post links to public Facebook profiles, and my site fetches the profile picture and displays it. Would it be ok if I just told people to post profiles of which they had the owner’s permission? Does such a statement exonerate me from copyright infringements and place the burden on the user? Edit: For bonus points. Can the statement just be a notice under the button (that will save the link) that says that "By clicking this button you agree to the terms and conditions" with maybe a link to the terms and conditions.

Read the article
How to design the scenarios in a platform game?

- by ReyLitch

I am developing a 3D platform game like Metroid Fusion with XNA. I have many classes for different elements as models, game screens, postprocessing and so on. Now I want to start designing the scenarios but I think that the scenarios needed in a platform game are not as conventional (by conventional I say something like this). I am very lost and not know where to start and how to structure it. Thanks in advance.

Read the article
Facebook Like button warning, but prevents sharing

- by Steve

I added a FB Like button to my Wordpress template, and when I click Like, I receive an error, which pops up and says: There was an error liking the page. If you are the page owner, please try running your page through the linter on the Facebook devsite (https://developers.facebook.com/tools/lint/) and fixing any errors. The Lint Checker (now) gives no Error or Warnings, after I removed a duplicate og:description tag. Why is it not working?

Read the article
Interoperability between two AES algorithms

- by lpfavreau

Hello, I'm new to cryptography and I'm building some test applications to try and understand the basics of it. I'm not trying to build the algorithms from scratch but I'm trying to make two different AES-256 implementation talk to each other. I've got a database that was populated with this Javascript implementation stored in Base64. Now, I'm trying to get an Objective-C method to decrypt its content but I'm a little lost as to where the differences in the implementations are. I'm able to encrypt/decrypt in Javascript and I'm able to encrypt/decrypt in Cocoa but cannot make a string encrypted in Javascript decrypted in Cocoa or vice-versa. I'm guessing it's related to the initialization vector, nonce, counter mode of operation or all of these, which quite frankly, doesn't speak to me at the moment. Here's what I'm using in Objective-C, adapted mainly from this and this: @implementation NSString (Crypto) - (NSString *)encryptAES256:(NSString *)key { NSData *input = [self dataUsingEncoding: NSUTF8StringEncoding]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:TRUE]; return [Base64 encode:output]; } - (NSString *)decryptAES256:(NSString *)key { NSData *input = [Base64 decode:self]; NSData *output = [NSString cryptoAES256:input key:key doEncrypt:FALSE]; return [[[NSString alloc] initWithData:output encoding:NSUTF8StringEncoding] autorelease]; } + (NSData *)cryptoAES256:(NSData *)input key:(NSString *)key doEncrypt:(BOOL)doEncrypt { // 'key' should be 32 bytes for AES256, will be null-padded otherwise char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused) bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding) // fetch key data [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding]; NSUInteger dataLength = [input length]; // See the doc: For block ciphers, the output size will always be less than or // equal to the input size plus the size of one block. // That's why we need to add the size of one block here size_t bufferSize = dataLength + kCCBlockSizeAES128; void* buffer = malloc(bufferSize); size_t numBytesCrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(doEncrypt ? kCCEncrypt : kCCDecrypt, kCCAlgorithmAES128, kCCOptionECBMode | kCCOptionPKCS7Padding, keyPtr, kCCKeySizeAES256, nil, // initialization vector (optional) [input bytes], dataLength, // input buffer, bufferSize, // output &numBytesCrypted ); if (cryptStatus == kCCSuccess) { // the returned NSData takes ownership of the buffer and will free it on deallocation return [NSData dataWithBytesNoCopy:buffer length:numBytesCrypted]; } free(buffer); // free the buffer; return nil; } @end Of course, the input is Base64 decoded beforehand. I see that each encryption with the same key and same content in Javascript gives a different encrypted string, which is not the case with the Objective-C implementation that always give the same encrypted string. I've read the answers of this post and it makes me believe I'm right about something along the lines of vector initialization but I'd need your help to pinpoint what's going on exactly. Thank you!

Read the article
Graphing per-user CPU usage on a Linux machine

- by mart1n

I want to graph (graphical output would be great, i.e. a .png file) the following situation: I have users A, B, and C. I limit their resources so that when all users run a CPU intensive task at the same time, those processes will use 25%, 25%, and 50% of CPU. I know I can get the real-time stats using top but have no idea what to do with them. I've searched through the huge top man page but haven't found much on the subject of outputting data that can be graphed. Ideally, the graph would show a span of maybe 30 seconds. Any ideas how to achieve this?

Read the article

< Previous Page | 34 35 36 37 38 39 40 41 42 43 44 45 | Next Page >