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  • What is the PIXELFORMATDESCRIPTOR parameter in SetPixelFormat() used for?

    - by Mads Elvheim
    Usually when setting up OpenGL contexts, I've simply filled out a PIXELFORMATDESCRIPTOR structure with the necessary information and called ChoosePixelFormat(), followed by a call to SetPixelFormat() with the returned matching pixelformat from ChoosePixelFormat(). Then I've simply passed the initial descriptor without giving much thought of why. But now I use wglChoosePixelFormatARB() instead if ChoosePixelFormat() because I need some extended traits like sRGB and multisampling. It takes an attribute list of integers, just like XLib/GLX on Linux, not a PIXELFORMATDESCRIPTOR structure. So, do I really have to fill in a descriptor for SetPixelFormat() to use? What does SetPixelFormat() use the descriptor for when it already has the pixelformat descriptor index? Why do I have to specify the same pixelformat attributes in two different places? And which one takes precedence; the attribute list to wglChoosePixelFormatARB(), or the PIXELFORMATDESCRIPTOR attributes passed to SetPixelFormat()? Here are the function prototypes, to make the question more clear: /* Finds a best match based on a PIXELFORMATDESCRIPTOR, and returns the pixelformat index */ int ChoosePixelFormat(HDC hdc, const PIXELFORMATDESCRIPTOR *ppfd); /* Finds a best match based on an attribute list of integers and floats, and returns a list of indices of matches, with the best matches at the head. Also supports extended pixelformat traits like sRGB color space, floating-point framebuffers and multisampling. */ BOOL wglChoosePixelFormatARB(HDC hdc, const int *piAttribIList, const FLOAT *pfAttribFList, UINT nMaxFormats, int *piFormats, UINT *nNumFormats ); /* Sets the pixelformat based on the pixelformat index */ BOOL SetPixelFormat(HDC hdc, int iPixelFormat, const PIXELFORMATDESCRIPTOR *ppfd);

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  • How to temporarily replace one primitive type with another when compiling to different targets in c#

    - by Keith
    How to easily/quickly replace float's for doubles (for example) for compiling to two different targets using these two particular choices of primitive types? Discussion: I have a large amount of c# code under development that I need to compile to alternatively use float, double or decimals depending on the use case of the target assembly. Using something like “class MYNumber : Double” so that it is only necessary to change one line of code does not work as Double is sealed, and obviously there is no #define in C#. Peppering the code with #if #else statements is also not an option, there is just too much supporting Math operators/related code using these particular primitive types. I am at a loss on how to do this apparently simple task, thanks! Edit: Just a quick comment in relation to boxing mentioned in Kyles reply: Unfortunately I need to avoid boxing, mainly since float's are being chosen when maximum speed is required, and decimals when maximum accuracy is the priority (and taking the 20x+ performance hit is acceptable). Boxing would probably rules out decimals as a valid choice and defeat the purpose somewhat. Edit2: For reference, those suggesting generics as a possible answer to this question note that there are many issues which count generics out (at least for our needs). For an overview and further references see Using generics for calculations

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  • Converting an input text value to a decimal number

    - by vitto
    Hi, I'm trying to work with decimal data in my PHP and MySql practice and I'm not sure about how can I do for an acceptable level af accuracy. I've wrote a simple function which recives my input text value and converts it to a decimal number ready to be stored in the database. <?php function unit ($value, $decimal_point = 2) { return number_format (str_replace (",", ".", strip_tags (trim ($value))), $decimal_point); } ?> I've resolved something like AbdlBsF5%?nl with some jQuery code for replace and some regex to keep only numbers, dots and commas. In some country, people uses the comma , to send decimal numbers, so a number like 72.08 is wrote like 72,08. I'd like avoid to forcing people to change their usual chars and I've decided to use a jQuery to keep this too. Now every web developer knows the last validation must be handled by the dynamic page for security reasons. So my answer is should I use something like unit (); function to store data or shoul I also check if users inserts invalid chars like letters or something else? If I try this and send letters, the query works without save the invalid data, I think this isn't bad, but I could easily be wrong because I'm a rookie. What kind of method should I use if I want a number like 99999.99 for my query?

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  • What algorithms are suitable for this simple machine learning problem?

    - by user213060
    I have a what I think is a simple machine learning question. Here is the basic problem: I am repeatedly given a new object and a list of descriptions about the object. For example: new_object: 'bob' new_object_descriptions: ['tall','old','funny']. I then have to use some kind of machine learning to find previously handled objects that had similar descriptions, for example, past_similar_objects: ['frank','steve','joe']. Next, I have an algorithm that can directly measure whether these objects are indeed similar to bob, for example, correct_objects: ['steve','joe']. The classifier is then given this feedback training of successful matches. Then this loop repeats with a new object. a Here's the pseudo-code: Classifier=new_classifier() while True: new_object,new_object_descriptions = get_new_object_and_descriptions() past_similar_objects = Classifier.classify(new_object,new_object_descriptions) correct_objects = calc_successful_matches(new_object,past_similar_objects) Classifier.train_successful_matches(object,correct_objects) But, there are some stipulations that may limit what classifier can be used: There will be millions of objects put into this classifier so classification and training needs to scale well to millions of object types and still be fast. I believe this disqualifies something like a spam classifier that is optimal for just two types: spam or not spam. (Update: I could probably narrow this to thousands of objects instead of millions, if that is a problem.) Again, I prefer speed when millions of objects are being classified, over accuracy. What are decent, fast machine learning algorithms for this purpose?

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  • Where to find algorithms for standard math functions?

    - by dsimcha
    I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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  • Auto-converting numbers to comma-fied versions

    - by Jeff Atwood
    Given the following text /feeds/tag/remote-desktop 1320 17007 22449240 /feeds/tag/terminal-server 1328 15805 20989040 /foo/23211/test 1490 11341 16898090 Let's say we want to convert those numbers to their comma-fied forms, like so /feeds/tag/remote-desktop 1,320 17,007 22,449,240 /feeds/tag/terminal-server 1,328 15,805 20,989,040 /foo/23211/test 1,490 11,341 16,898,090 (don't worry about fixing the fixed-width ASCII spacing, that's a problem for another day) This is the best regex I could come up with; it's based on this JavaScript regex solution from Regex Ninja Steven Levithan: return Regex.Replace(s, @"\b(?<!\/)\d{4,}\b(?<!\/)", delegate(Match match) { string output = ""; string m = match.Value; int len = match.Length; for (int i = len - 1; i >= 0 ; i--) { output = m[i] + output; if ((len - i) % 3 == 0) output = "," + output; } if (output.StartsWith(",")) output = output.Substring(1, output.Length-1); return output; }); In a related question, there is a very clever number comma insertion regex proposed: text = Regex.Replace(text, @"(?<=\d)(?=(\d{3})+$)", ",") However this requires an end anchor $ which, as you can see, I don't have in the above text -- the numbers are "floating" in the rest of the text. I suspect there is a cleaner way to do this than my solution? After writing this, I just realized I could combine them, and put one Regex inside the other, like so: return Regex.Replace(s, @"\b(?<!\/)\d{4,}\b(?<!\/)", delegate(Match match) { return Regex.Replace(match.Value, @"(?<=\d)(?=(\d{3})+$)", ","); });

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  • Putting CAPTCHAs on their own page?

    - by mnemosyn
    We need to put a captcha image on our ASP.NET MVC 2 based website. We chose reCaptcha and built it in using the way described by Derik Whittaker. The idea there is baiscally to build some abstractions and all you need to do is decorate your Controller with a [ValidateCaptcha] attribute. This works all fine. However, we have a lot of form-widgets in different pages and I don't want to have the captcha floating around everywhere. So I'd like to implement it the way StackOverflow does: Submit a Form -> Challenge Captcha -> Submit Captcha -> Perform Action on original form data. Now, how do I redirect the user to the captcha page while keeping the originally submitted information? I thought of some very ugly hacks (hidden fields w/ base64 encoded form data, etc.) but I think I'm missing something obvious. On the other hand, this sounds as if I wanted to do something in a stateful manner, and I shouldn't?

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  • get lattitude and longitude of a place against its zipcode

    - by yunas
    Hello i have used the following code to get the location of the particular place on map using the following piece of code NSString * urlString = [[NSString alloc] initWithFormat:@"http://maps.google.com/maps/geo?key=%@&output=xml&q=%@",GoogleMapsAPIKey,[placeName stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]]; result: <?xml version="1.0" encoding="UTF-8" ?> <kml xmlns="http://earth.google.com/kml/2.0"><Response> <name>postdam</name> <Status> <code>200</code> <request>geocode</request> </Status> <Placemark id="p1"> <address>Potsdam, Germany</address> <AddressDetails Accuracy="4" xmlns="urn:oasis:names:tc:ciq:xsdschema:xAL:2.0"><Country><CountryNameCode>DE</CountryNameCode><CountryName>Deutschland</CountryName><AdministrativeArea><AdministrativeAreaName>Brandenburg</AdministrativeAreaName><SubAdministrativeArea><SubAdministrativeAreaName>Potsdam</SubAdministrativeAreaName><Locality><LocalityName>Potsdam</LocalityName></Locality></SubAdministrativeArea></AdministrativeArea></Country></AddressDetails> <ExtendedData> <LatLonBox north="52.4513968" south="52.3424614" east="13.1866602" west="12.9305414" /> </ExtendedData> <Point><coordinates>13.0586008,52.3969627,0</coordinates></Point> </Placemark> </Response></kml> but now i want to get the information agianst the zipcode how to do that using the maps.google.com ???

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  • Testing fault tolerant code

    - by Robert
    I’m currently working on a server application were we have agreed to try and maintain a certain level of service. The level of service we want to guaranty is: if a request is accepted by the server and the server sends on an acknowledgement to the client we want to guaranty that the request will happen, even if the server crashes. As requests can be long running and the acknowledgement time needs be short we implement this by persisting the request, then sending an acknowledgement to the client, then carrying out the various actions to fulfill the request. As actions are carried out they too are persisted, so the server knows the state of a request on start up, and there’s also various reconciliation mechanisms with external systems to check the accuracy of our logs. This all seems to work fairly well, but we have difficult saying this with any conviction as we find it very difficult to test our fault tolerant code. So far we’ve come up with two strategies but neither is entirely satisfactory: Have an external process watch the server code and then try and kill it off at what the external process thinks is an appropriate point in the test Add code the application that will cause it to crash a certain know critical points My problem with the first strategy is the external process cannot know the exact state of the application, so we cannot be sure we’re hitting the most problematic points in the code. My problem with the second strategy, although it gives more control over were the fault takes, is I do not like have code to inject faults within my application, even with optional compilation etc. I fear it would be too easy to over look a fault injection point and have it slip into a production environment.

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  • GLSL shader render to texture not saving alpha value

    - by quadelirus
    I am rendering to a texture using a GLSL shader and then sending that texture as input to a second shader. For the first texture I am using RGB channels to send color data to the second GLSL shader, but I want to use the alpha channel to send a floating point number that the second shader will use as part of its program. The problem is that when I read the texture in the second shader the alpha value is always 1.0. I tested this in the following way: at the end of the first shader I did this: gl_FragColor(r, g, b, 0.1); and then in the second texture I read the value of the first texture using something along the lines of vec4 f = texture2D(previous_tex, pos); if (f.a != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } No pixels in my output are black, whereas if I change the above code to read gl_FragColor(r, g, 0.1, 1.0); //Notice I'm now sending 0.1 for blue and in the second shader vec4 f = texture2D(previous_tex, pos); if (f.b != 1.0) { gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0); return; } All the appropriate pixels are black. This means that for some reason when I set the alpha value to something other than 1.0 in the first shader and render to a texture, it is still seen as being 1.0 by the second shader. Before I render to texture I glDisable(GL_BLEND); It seems pretty clear to me that the problem has to do with OpenGL handling alpha values in some way that isn't obvious to me since I can use the blue channel in the way I want, and figured someone out there will instantly see the problem.

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  • Creating a fixed length output string with sprintf containing floats

    - by Kungi
    Hi, I'm trying to create a file which has the following structure: - Each line has 32 bytes - Each line looks like this format string: "%10i %3.7f %3.7f\n" My Problem is the following: When i have a negative floating point numbers the line gets longer by one or even two characters because the - sign does not count to the "%3.7f". Is there any way to do this more nicely than this? if( node->lng > 0 && node->lat > 0 ) { sprintf( osm_node_repr, "%10i %3.7f %3.7f\n", node->id, node->lng, node->lat ); } else if (node->lng > 0 && node->lat < 0) { sprintf( osm_node_repr, "%10i %3.7f %3.6f\n", node->id, node->lng, node->lat ); } else if (node->lng < 0 && node->lat > 0) { sprintf( osm_node_repr, "%10i %3.6f %3.7f\n", node->id, node->lng, node->lat ); } else if ( node->lng < 0 && node->lat < 0 ) { sprintf( osm_node_repr, "%10i %3.6f %3.6f\n", node->id, node->lng, node->lat ); } Thanks for your Answers, Andreas

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  • DIVS over flash movies in Internet Explorer

    - by drew
    The age old question... why the hell doesn't a div positioned over a flash object stay on top with z-index. I have found the answer in the past, but it's been so long, I can't seem to get it. My flash movie is in a div floating left: <div id="flash"> <object width="614" height="289"> <param name="movie" value="images/75.swf"> <param name="wmode" value="transparent"> <embed src="images/75.swf" width="614" height="289" wmode"transparent"> </embed> </object> </div> My css for the div that needs to be on top is: .menu ul li:hover ul li a:hover { background:#5a3f2d; color:#FFF; z-index: 9999; I cannot get it to show above the flash movie in ie6 or ie8. I know this is old school but I'm frustrated! Does my nav div need to have an absolute position? Is that why it doesn't work? Example is here. Hover over the first link on the right: "CUSTOMER SERVICE" Thanks all :)

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  • Can I ignore a SIGFPE resulting from division by zero?

    - by Mikeage
    I have a program which deliberately performs a divide by zero (and stores the result in a volatile variable) in order to halt in certain circumstances. However, I'd like to be able to disable this halting, without changing the macro that performs the division by zero. Is there any way to ignore it? I've tried using #include <signal.h> ... int main(void) { signal(SIGFPE, SIG_IGN); ... } but it still dies with the message "Floating point exception (core dumped)". I don't actually use the value, so I don't really care what's assigned to the variable; 0, random, undefined... EDIT: I know this is not the most portable, but it's intended for an embedded device which runs on many different OSes. The default halt action is to divide by zero; other platforms require different tricks to force a watchdog induced reboot (such as an infinite loop with interrupts disabled). For a PC (linux) test environment, I wanted to disable the halt on division by zero without relying on things like assert.

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  • Calculating bounding box a certain distance away from a lat/long coordinate in Java

    - by Bryce Thomas
    Given a coordinate (lat, long), I am trying to calculate a square bounding box that is a given distance (e.g. 50km) away from the coordinate. So as input I have lat, long and distance and as output I would like two coordinates; one being the south-west (bottom-left) corner and one being the north-east (top-right) corner. I have seen a couple of answers on here that try to address this question in Python, but I am looking for a Java implementation in particular. Just to be clear, I intend on using the algorithm on Earth only and so I don't need to accommodate a variable radius. It doesn't have to be hugely accurate (+/-20% is fine) and it'll only be used to calculate bounding boxes over small distances (no more than 150km). So I'm happy to sacrifice some accuracy for an efficient algorithm. Any help is much appreciated. Edit: I should have been clearer, I really am after a square, not a circle. I understand that the distance between the center of a square and various points along the square's perimeter is not a constant value like it is with a circle. I guess what I mean is a square where if you draw a line from the center to any one of the four points on the perimeter that results in a line perpendicular to a side of the perimeter, then those 4 lines have the same length.

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  • Is there a java library / package analogous to <stdio.h>?

    - by Roboprog
    I have been doing Java on and off for about 14 years, and almost nothing else the last 6 years or so. I really hate the java.io package -- its legion of subclasses and adapters. I do like exceptions, rather than having to always poll "errno" and the like, but I could surely live without declared exceptions. Is there anything that functions like the Unix/ANSI stdio.h routines in C? I know we will never be rid of java.io and its conventions until java itself is retired, as they have metastasized throughout the many frameworks that have accreted to java. That said, I would like something that works kind of like this (let's call it package javax.stdio): Have a main utility class, perhaps FileStar, that can read and write files (or pipes), either text or binary, either sequentially or random access, with constructors that mimic fopen() and popen(). This class should have a load of useful methods that do things like fread(), fwrite(), fgets(), fputs(), fseek(), and whatever else (fprintf()?). Methods that are incompatible with the open/construct mode simply throw up (just like some of the collections classes/methods do when restricted). Then, have a bunch of interfaces that suggest how you intend to use the stream once you have created it: Sequential, RandomAccess, ReadOnly, WriteOnly, Text, Binary, plus combinations of these that make sense. Perhaps even have methods to return the appropriate type-cast (interface), throwing up if you have asked for something incompatible. For extra flavor, skip the declared exceptions -- e.g. - javax.stdio.IOException extends RuntimeException. Is there an open source project like this floating around?

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  • text not wrapping around some floated images, wraps in IE & FF but not chrome, safari

    - by Hartley
    This is unlike anything I've read about and I've been totally scratching my head for the last few hours trying to figure out what's going on. I have a hand-coded site @ hartbro.com Part of the site is a blog, in which I include pictures. Here's the HTML code around one of the images that's causing trouble. <a href="blogcontent/090811.jpg" class="img"> <img src="blogcontent/090811.jpg" alt="Downed trees" width="25%" class="floatright" /></a> The storm left as quickly as it came. The sky cleared up and we were glad that the oppressive heat had let up. What I've noticed is that, on some of the blog entries that include more than one image, the 2nd image isn't really floating like its supposed to be, with the text wrapping around it. I figure its got to be some sort of conflict with some CSS that I have that's causing the problem but I just can't figure out what it is. I don't understand how it works in FF & IE but not Chrome or Safari?? Here's all of the relevant CSS, let me know if you need anything else. Thanks in advance. img{ margin:10px; } img.floatleft{ float:left; } img.floatright{ float:right; } edit: here's an screen-shot of what's happening.

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  • How to read/write high-resolution (24-bit, 8 channel) .wav files in Java?

    - by dB'
    I'm trying to write a Java application that manipulates high resolution .wav files. I'm having trouble importing the audio data, i.e. converting the .wav file into an array of doubles. When I use a standard approach an exception is thrown. AudioFileFormat as = AudioSystem.getAudioFileFormat(new File("orig.wav")); --> javax.sound.sampled.UnsupportedAudioFileException: file is not a supported file type Here's the file format info according to soxi: dB$ soxi orig.wav soxi WARN wav: wave header missing FmtExt chunk Input File : 'orig.wav' Channels : 8 Sample Rate : 96000 Precision : 24-bit Duration : 00:00:03.16 = 303526 samples ~ 237.13 CDDA sectors File Size : 9.71M Bit Rate : 24.6M Sample Encoding: 32-bit Floating Point PCM Can anyone suggest the simplest method for getting this audio into Java? I've tried using a few techniques. As stated above, I've experimented with the Java AudioSystem (on both Mac and Windows). I've also tried using Andrew Greensted's WavFile class, but this also fails (WavFileException: Compression Code 3 not supported). One workaround is to convert the audio to 16 bits using sox (with the -b 16 flag), but this is suboptimal since it increases the noise floor. Incidentally, I've noticed that the file CAN be read by libsndfile. Is my best bet to write a jni wrapper around libsndfile, or can you suggest something quicker? Note that I don't need to play the audio, I just need to analyze it, manipulate it, and then write it out to a new .wav file. * UPDATE * I solved this problem by modifying Andrew Greensted's WavFile class. His original version only read files encoded as integer values ("format code 1"); my files were encoded as floats ("format code 3"), and that's what was causing the problem. I'll post the modified version of Greensted's code when I get a chance. In the meantime, if anyone wants it, send me a message.

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  • Java SSH2 libraries in depth: Trilead/Ganymed/Orion [/other?]

    - by Bernd Haug
    I have been searching for a pure Java SSH library to use for a project. The single most important needed feature is that it has to be able to work with command-line git, but remote-controlling command-line tools is also important. A pretty common choice, e.g. used in the IntelliJ IDEA git integration (which works very well), seems to be Trilead SSH2. Looking at their website, it's not being maintained any more. Trilead seems to have been a fork of Ganymed SSH2, which was a ETH Zurich project that didn't see releases for a while, but had a recent release by its new owner, Christian Plattner. There is another actively maintained fork from that code base, Orion SSH, that saw an even more recent release, but which seems to get mentioned online much less than the other 2 forks. Has anybody here worked with any of (or, if possible, both) of Ganymed and Orion and could kindly describe the development experience with either/both? Accuracy of documentation [existence of documentation?], stability, buggyness... - all of these would be highly interesting to me. Performance is not so important for my current project. If there is another pure-Java SSH implementation that should be used instead, please feel free to mention it, but please don't just mention a name...describe your judgment from actual experience. Sorry if this question may seem a bit "do my homework"-y, but I've really searched for reviews. Everything out there seems to be either a listing of implementations or short "use this! it's great!" snippets.

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  • Performance of Java matrix math libraries?

    - by dfrankow
    We are computing something whose runtime is bound by matrix operations. (Some details below if interested.) This experience prompted the following question: Do folk have experience with the performance of Java libraries for matrix math (e.g., multiply, inverse, etc.)? For example: JAMA: http://math.nist.gov/javanumerics/jama/ COLT: http://acs.lbl.gov/~hoschek/colt/ Apache commons math: http://commons.apache.org/math/ I searched and found nothing. Details of our speed comparison: We are using Intel FORTRAN (ifort (IFORT) 10.1 20070913). We have reimplemented it in Java (1.6) using Apache commons math 1.2 matrix ops, and it agrees to all of its digits of accuracy. (We have reasons for wanting it in Java.) (Java doubles, Fortran real*8). Fortran: 6 minutes, Java 33 minutes, same machine. jvisualm profiling shows much time spent in RealMatrixImpl.{getEntry,isValidCoordinate} (which appear to be gone in unreleased Apache commons math 2.0, but 2.0 is no faster). Fortran is using Atlas BLAS routines (dpotrf, etc.). Obviously this could depend on our code in each language, but we believe most of the time is in equivalent matrix operations. In several other computations that do not involve libraries, Java has not been much slower, and sometimes much faster.

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  • Float a div in top right corner without overlapping sibling header

    - by Maxime R.
    Having a div and a h1 inside a section, how do i float the div in the top right corner without overlapping the text of the header ? The HTML code is the following: <section> <h1>some long long long long header, a whole line, 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6</h1> <div><button>button</button></div> </section> I tried an absolute position relative to the parent but the text is overlapped, http://jsfiddle.net/FnpS8/2/ Using this CSS code: section { position: relative; } h1 { display: inline; } div { position: absolute; top: 0; right: 0; } I tried floating the div to the right but it doesn't remain in the top right corner, http://jsfiddle.net/P6xCw/2/ Using this CSS code: h1 { display: inline; } div { float: right; } ? I know there is a lot of similar questions but I couldn't find one solving this case.

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  • Fast, very lightweight algorithm for camera motion detection?

    - by Ertebolle
    I'm working on an augmented reality app for iPhone that involves a very processor-intensive object recognition algorithm (pushing the CPU at 100% it can get through maybe 5 frames per second), and in an effort to both save battery power and make the whole thing less "jittery" I'm trying to come up with a way to only run that object recognizer when the user is actually moving the camera around. My first thought was to simply use the iPhone's accelerometers / gyroscope, but in testing I found that very often people would move the iPhone at a consistent enough attitude and velocity that there wouldn't be any way to tell that it was still in motion. So that left the option of analyzing the actual video feed and detecting movement in that. I got OpenCV working and tried running their pyramidal Lucas-Kanade optical flow algorithm, which works well but seems to be almost as processor-intensive as my object recognizer - I can get it to an acceptable framerate if I lower the depth levels / downsample the image / track fewer points, but then accuracy suffers and it starts to miss some large movements and trigger on small hand-shaking-y ones. So my question is, is there another optical flow algorithm that's faster than Lucas-Kanade if I just want to detect the overall magnitude of camera movement? I don't need to track individual objects, I don't even need to know which direction the camera is moving, all I really need is a way to feed something two frames of video and have it tell me how far apart they are.

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  • Android Accessing Accelerometer: Returns always 0 as Value

    - by Rotesmofa
    Hello there, i would like to use the accelerometer in an Android Handset for my Application. The data from the sensor will be saved together with a GPS Point, so the Value is only needed when the GPS Point is updated. If i use the attached Code the values is always zero. API Level 8 Permissions: Internet, Fine Location Testing Device: Galaxy S(i9000), Nexus One Any Suggestions? I am stuck at this point. Best regards from Germany, Pascal import android.app.Activity; import android.hardware.Sensor; import android.hardware.SensorEvent; import android.hardware.SensorEventListener; import android.hardware.SensorManager; import android.os.Bundle; public class AccelerometerService extends Activity{ AccelerometerData accelerometerData; private SensorManager mSensorManager; private float x,y,z; private class AccelerometerData implements SensorEventListener{ public void onSensorChanged(SensorEvent event) { x = event.values[0]; y = event.values[1]; z = event.values[2]; } public void onAccuracyChanged(Sensor sensor, int accuracy) {} } @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE); mSensorManager.registerListener(accelerometerData, mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_FASTEST); } @Override protected void onResume() { super.onResume(); } @Override protected void onStop() { mSensorManager.unregisterListener(accelerometerData); super.onStop(); } public String getSensorString() { return ("X: " + x+"m/s, Y: "+ y +"m/s, Z: "+ z +"m/s" ); } }

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  • HighCharts : Can I customize the colors of individual series?

    - by user1091114
    I am using HighCharts for a line graph and i am attemping to change the line color for each series. I did find this example here but the data is hard coded. My data is pulled from an Sql database and passed to the HTML page using some VB code. var chart; $(document).ready(function () { chart = new Highcharts.Chart({ chart: { renderTo: 'container', defaultSeriesType: 'column' }, title: { text: 'Chart Title' }, subtitle: { text: 'Chart subtitle' }, xAxis: { categories: [<%= GraphDate %>] , labels: { rotation: -45, align: 'right', style: { } } }, yAxis: { min: 160, title: { text: 'Temp' } }, legend: { layout: 'vertical', backgroundColor: '#FFFFFF', align: 'left', verticalAlign: 'top', x: 400, y: 0, floating: true, shadow: true }, tooltip: { formatter: function () { return '' + this.x + ': ' + this.y + ' ºC'; } }, plotOptions: { column: { pointPadding: 0.2, borderWidth: 0 } }, series: [<%= GraphSeries %>], }); I tried to style it using the other post however it failed to generate a chart. The main problem is though, the line graph has two series, so the below method would set the color for both series i assume? So, would i maybe need to format the series in my vb code somehow? series: [{ color: 'yellow', data: [ [<%= GraphSeries %>] ]},

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  • WPF - Why doesn't Microsoft supply a decent set of most-used controls ?

    - by IUsedToBeAPygmy
    I've been playing with WPF for some months now, and I quite like it. But one of the things I don't get is why MS doesn't put a little more effort in helping developers by supplying basic controls, and I need to get this off my chest :) For example, I figure most applications somewhere will need to let you edit some properties - for configuration or whatever. What would be the most used types in a proprety-grid editor ? text numbers (byte, float/double, int, etc) colors ....etc. So why isn't there even something as simple as a control to edit numbers ? Like a generic NumericUpDown control that allows you to type in numbers (no text, no pasting invalid input) or spin them up/down according to some given rules (decimal, floating point, min/maxvalue) ? Why isn't there a generic colorpicker, so people get the same user-experience in every application ? Why isn't there a standard implementation of a SearchTextBox, a BreadCrumb-control, or all these other standard control types users have gotten accustomed to the last 10 years ? (..but at least they DID have the time to implement a generic splashscreen - because everyone knows that greatly increases user-productivity....) The well-known ideal is always to give people the same user-experience over different applications. So even if some of those controls would be easy to make - it would be preferred to have one version over different applications. I see people all over the internet trying to do the same stuff over and over again. Okay, so MS started a WPF Toolkit project on Codeplex that tries to implement some controls, but only did so half-heartedly and is completely dead by now (last update of the roadmap dates back to Mar 21 2009). The result of this is that a lot of people starting a WPF-project end up spending a lot of time on trying to figure out how to create some generic controls and get really frustrated. Wasn't the mantra "Developers, developers, developers!" ..? /Rant

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  • 1k of Program Space, 64 bytes of RAM. Is assembly an absolute must?

    - by Earlz
    (If your lazy see bottom for TL;DR) Hello, I am planning to build a new (prototype) project dealing with physical computing. Basically, I have wires. These wires all need to have their voltage read at the same time. More than a few hundred microseconds difference between the readings of each wire will completely screw it up. The Arduino takes about 114 microseconds. So the most I could read is 2 or 3 wires before the latency would skew the accuracy of the readings. So my plan is to have an Arduino as the "master" of an array of ATTinys. The arduino is pretty cramped for space, but it's a massive playground compared to the tinys. An ATTiny13A has 1k of flash ROM(program space), 64 bytes of RAM, and 64 bytes of (not-durable and slow) EEPROM. (I'm choosing this for price as well as size) The ATTinys in my system will not do much. Basically, all they will do is wait for a signal from the Master, and then read the voltage of 1 or 2 wires and store it in RAM(or possibly EEPROM if it's that cramped). And then send it to the Master using only 1 wire for data.(no room for more than that!). So far then, all I should have to do is implement trivial voltage reading code (using built in ADC). But this communication bit I'm worried about. Do you think a communication protocol(using just 1 wire!) could even be implemented in such constraints? TL;DR: In less than 1k of program space and 64 bytes of RAM(and 64 bytes of EEPROM) do you think it is possible to implement a 1 wire communication protocol? Would I need to drop to assembly to make it fit? I know that currently my Arduino programs linking to the Wiring library are over 8k, so I'm a bit concerned.

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