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  • Function approximation with Maclaurin series

    - by marines
    I need to approx (1-x)^0.25 with given accuracy (0.0001 e.g.). I'm using expansion found on Wikipedia for (1+x)^0.25. I need to stop approximating when current expression is less than the accuracy. long double s(long double x, long double d) { long double w = 1; long double n = 1; // nth expression in series long double tmp = 1; // sum while last expression is greater than accuracy while (fabsl(tmp) >= d) { tmp *= (1.25 / n - 1) * (-x); // the next expression w += tmp; // is added to approximation n++; } return w; } Don't mind long double n. :P This works well when I'm not checking value of current expression but when I'm computing 1000 or more expressions. Domain of the function is <-1;1 and s() calculates approximation well for x in <-1;~0.6. The bigger the argument is the bigger is the error of calculation. From 0.6 it exceeds the accuracy. I'm not sure if the problem is clear enough because I don't know English math language well. The thing is what's the matter with while condition and why the function s() doesn't approximate correctly.

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  • Dynamically manipulate php cookies with javascript/jquery

    - by pundit
    Hi guys, I'm currently building a dynamic menu bar(vertical and horizontal). in the default position its vertical. the user have the option to show the horizontal position and hide and vertical. I am currently doing that with javascript/ jquery. in order to keep the menu bar in the horizontal position i am keeping a count with a cookie. the problem is that when i use the click function in javascript i want to change the value of the cookie. i have no knowledge of how to do this. Can anyone assist me with this. all help would be appreciated. <?php setcookie('menu', 1, time()+(86400)); ?> $(document).ready(function() { $('#temp').hide(); if(<?php echo $_COOKIE['menu'];?> == 1){ $('#topmenu').hide(); $('#sidemenu').floating().dropShadow().floating(); $('#sidemenu_bottom').hide(); }else{ $('#topmenu').show(); $('#topmenu').dropShadow(); $('#sidemenu').hide(); $('#sidemenu').removeShadow(); } $('#move').click(function(){ $('#sidemenu').hide("drop",{},2000); $('#sidemenu').removeShadow(); $('#topmenu').show(); $('#topmenu').dropShadow(); $('#sidemenu_bottom').show(); $('#sidemenu_bottom').floating().dropShadow().floating(); }); }); This is what i have so far and the default cookie is working as well as the javascript. its just to change the cookie value now. thanks.

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  • Delphi fsstayontop oddity

    - by TallGuy
    Here is the deal. Main form set to fsnormal. This main form is maximized full screen with a floating toolbar. Toolbar is normal form with style set to fsstayontop. Most fo the time this works as expected. The mainform displays and the toolbar floats over on top of it. Sometimes (this is a bugger to find a reproducable set of steps) when alt-tabbing to and from other apps (or when clicking the delphi app icon on the taskbar) the following symptoms can happen... When alt-tabbing away from the delphi app the floating topmost fsstayontop form stays on top of the other apps. So if I alt-tab to firefox then the floating menu stays on top of firefox too. When alt-tabbing from another app to the delphi app the flaoting menu is not visible (as it is behhind the fsnormal mainform). Is there a known bug or any hacks to force it to work? This also seems to happen most when mutliple copies of the app are running (they have no interaction between them and should be running in their own windows "sandbox"). It is as if delphi gets confused which window is meant to be on top and swaps them or changes the floating form to stayontopofeverything mode. Or have I misunderstood fsstayontop? I am assuming setting a form style to fsstayontop makes it stay on top of all other forms within the current app and not all windows across other running apps. Thanks for any tips or workarounds.

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  • Why doesn't my <div> float around another floated <div> while other elements do?

    - by user1848605
    I have a container with background color green. Inside that green <div>, I have a <div> which is black and styled as a box (50px x 50px) - this <div> is floated to the left. Now if I add a <p> to my markup after the grey <div>, I'd expect it to float around the grey <div>. And it does. However, when I substitue with another <div> which is styled as box (set height and width), it doesn't float around anymore, but disappears behind the floating div. Even if I have first paragraphs which are floating around correctly and THEN I add the div (box), the paragraphs stop floating around and appear on another line. HTML: <div id="greencontainer"> <div id="blackbox"></div> <!--this one is float:left;--> <p>A paragraph that floats around the previous div</p> <div id="anotherbox"></div> <!-- if I add another div with set width and height, it disappears behind the floated one, and even prevents the paragraph from floating around.--> </div> CSS: #blackbox { width:50px; height:50px; background-color:black; float:left; } #p { margin:0px; padding:0px; } #anotherbox { width:50px; height:50px; background-color:grey; }

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  • ansi-c fscanf problem

    - by mongoose
    hi i read the file as follows fscanf(fp,"%f %f %f",&*(p1+i), &*(p2+i), &*(p3+i)); my file's lines consists of three floating point numbers... the problem i have is that in the file let's say i have some floating points with let's say maximum of two digits after the dot. but when i ask c to print those values using different formatting, for example %lf,%.2lf,%.4lf... it starts to play with the digits... my only concern is this, if i have let's say 1343.23 in the file, then will c use this value exactly as it is in computations or it will play with the digits after the dot. if it will play, then how is it possible to make it so that it uses floating point numbers exactly as they are? for example in last case even if i ask it to print that value using %.10lf i would expect it to print only 1343.2300000000.? thanks a lot!

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  • Convert Double to String without precision loss in javascript

    - by holger
    I would like to convert a floating point variable to a string without losing any precision. I.e. I would like the string to have the same information as my floating point variable contains, since I use the output for further processing (even if it means that the string will be very long and readable). To put this more clearly, I would like to have functions for cyclic conversion var dA = 323423.23423423e4; var sA = toString(dA); var dnA = toDouble(sA); and I would like dnA and dA to be equal Thanks PS: Sources on the internet usually talk about how to round strings but I have not found information on exact representation. Also I am not interested in Arbitrary Precision calculations, I just need double precision floating point arithmetic.

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  • How to define a multipage environment not interrupted by tables and figures?

    - by Egon Willighagen
    I have defined a new LaTeX environment for excursions in a book chapter I am writing. The environment is multipage and often includes inline images. Moreover, I am using the shaded environment to give the environment a background colour to make it stand out a bit. However, the environment, as shown below, is split up by floating tables and images, which makes the flow of the environment visually more difficult to follow. For example, it is now difficult to see if that floating image or table is part (the missing background colour does not help). So, I like to extend my environment to disallow it to be interrupted by floating elements, but do not know how to get that done. \newcounter{bioclipse} \def\thebioclipse{\thechapter-\arabic{bioclipse}} \newenvironment{bioclipse}[2][]{\begin{small}\begin{shaded}\refstepcounter{bioclipse} \par\medskip\noindent% \textbf{Bioclipse Excursion~\thebioclipse #1: #2 \vspace{0.1cm} \hrule \vspace{0.1cm}} \rmfamily}{\medskip \end{shaded}\end{small}} Any solution to disallow interruption is fine, even if the background colour is done differently.

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  • SmoothLife Is a Super Smooth Version of Conway’s Game of Life [Video]

    - by Jason Fitzpatrick
    What happens if you change cellular automaton program Game of Life to use floating point values instead of integers? You end up with SmoothLife, a fluid and organic growth simulator. SmoothLife is a family of rules created by Stephan Rafler. It was designed as a continuous version of Conway’s Game of Life – using floating point values instead of integers. This rule is SmoothLifeL which supports many interesting phenomena such as gliders that can travel in any direction, rotating pairs of gliders, wickstretchers and the appearance of elastic tension in the ‘cords’ that join the blobs. You can check out the paper outlining how SmoothLife works here and then grab the source code to run your own simulation here. [via Boing Boing] HTG Explains: What is the Windows Page File and Should You Disable It? How To Get a Better Wireless Signal and Reduce Wireless Network Interference How To Troubleshoot Internet Connection Problems

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  • Digital Storage for Airline Entertainment

    - by Bill Evjen
    by Thomas Coughlin Common flash memory cards The most common flash memory products currently in use are SD cards and derivative products (e.g. mini and micro-SD cards) Some compact flash used for professional applications (such as DSLR cameras) Evolution of leading flash formats Standardization –> market expansion Market expansion –> volume iNAND –> focus is on enabling embedded X3 iSSD –> ideal for thin form factor devices Flash memory applications Phones are the #1 user of flash memory Flash memory is used as embedded and removable storage in many mobile applications Flash memory is being used in computers as USB sticks and SSDs Possible use of flash memory in computer combined with HDDs (hybrid HDDs and paired or dual storage computers) It can be a removable card or an embedded card These devices can only handle a specific number of writes Flash memory reads considerably quicker than hard drives Hybrid and dual storage in computers SSDs can provide fast performance but they are expensive HDDs can provide cheap storage but they are relatively slow Combining some flash memory with a HDD can provide costs close to those of HDDs and performance close to flash memory Seagate Momentus XT hybrid HDD Various dual storage offerings putting flash memory with HDDs Other common flash memory devices USB sticks All forms and colors Used for moving files around Some sold with content on them (Sony Movies on USB sticks) Solid State Drives (SSDs) Floating Gate Flash Memory Cell When a bit is programmed, electrons are stored upon the floating gate This has the effect of offsetting the charge on the control gate of the transistor If there is no charge upon the floating gate, then the control gate’s charge determines whether or not a current flows through the channel A strong charge on the control gate assumes that no current flows. A weak charge will allow a strong current to flow through. Similar to HDDs, flash memory must provide: Bit error correction Bad block management NAND and NOR memories are treated differently when it comes to managing wear In many NOR-based systems no management is used at all, since the NOR is simply used to store code, and data is stored in other devices. In this case, it would take a near-infinite amount of time for wear to become an issue since the only time the chip would see an erase/write cycle is when the code in the system is being upgraded, which rarely if ever happens over the life of a typical system. NAND is usually found in very different application than is NOR Flash memory wears out This is expected to get worse over time Retention: Disappearing data Bits fade away Retention decreases with increasing read/writes Bits may change when adjacent bits are read Time and traffic are concerns Controllers typically groom read disturb errors Like DRAM refresh Increases erase/write frequency Application characteristics Music – reads high / writes very low Video – r high / writes very low Internet Cache – r high / writes low On airplanes Many consumers now have their own content viewing devices – do they need the airlines? Is there a way to offer more to consumers, especially with their own viewers Additional special content tie into airplane network access to electrical power, internet Should there be fixed embedded or removable storage for on-board airline entertainment? Is there a way to leverage personal and airline viewers and content in new and entertaining ways?

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  • Is there a way to group 2 or 3 gui windows so that they don't get lost behind other open windows?

    - by Gonzalo
    For instance floating panels and main window in Gimp are independent windows. If I change focus to a full window (e.g. Firefox by doing Alt-Shift) and go back to the main Gimp window I don't get back the floating panels also (I have to change to them as well in order to see them). It would be great if the 3 windows can be "tied" (or linked) together in order that they don't get lost behind other open windows when I change back to (make active window) any of them? I think this configuration (if it exists) should show itself more obviously in the gnome environment. This question seems to address the same problem but it doesn't seem to be accurately answered.

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  • Compiling for T4

    - by Darryl Gove
    I've recently had quite a few queries about compiling for T4 based systems. So it's probably a good time to review what I consider to be the best practices. Always use the latest compiler. Being in the compiler team, this is bound to be something I'd recommend But the serious points are that (a) Every release the tools get better and better, so you are going to be much more effective using the latest release (b) Every release we improve the generated code, so you will see things get better (c) Old releases cannot know about new hardware. Always use optimisation. You should use at least -O to get some amount of optimisation. -xO4 is typically even better as this will add within-file inlining. Always generate debug information, using -g. This allows the tools to attribute information to lines of source. This is particularly important when profiling an application. The default target of -xtarget=generic is often sufficient. This setting is designed to produce a binary that runs well across all supported platforms. If the binary is going to be deployed on only a subset of architectures, then it is possible to produce a binary that only uses the instructions supported on these architectures, which may lead to some performance gains. I've previously discussed which chips support which architectures, and I'd recommend that you take a look at the chart that goes with the discussion. Crossfile optimisation (-xipo) can be very useful - particularly when the hot source code is distributed across multiple source files. If you're allowed to have something as geeky as favourite compiler optimisations, then this is mine! Profile feedback (-xprofile=[collect: | use:]) will help the compiler make the best code layout decisions, and is particularly effective with crossfile optimisations. But what makes this optimisation really useful is that codes that are dominated by branch instructions don't typically improve much with "traditional" compiler optimisation, but often do respond well to being built with profile feedback. The macro flag -fast aims to provide a one-stop "give me a fast application" flag. This usually gives a best performing binary, but with a few caveats. It assumes the build platform is also the deployment platform, it enables floating point optimisations, and it makes some relatively weak assumptions about pointer aliasing. It's worth investigating. SPARC64 processor, T3, and T4 implement floating point multiply accumulate instructions. These can substantially improve floating point performance. To generate them the compiler needs the flag -fma=fused and also needs an architecture that supports the instruction (at least -xarch=sparcfmaf). The most critical advise is that anyone doing performance work should profile their application. I cannot overstate how important it is to look at where the time is going in order to determine what can be done to improve it. I also presented at Oracle OpenWorld on this topic, so it might be helpful to review those slides.

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  • WebCenter Customer Spotlight: Alberta Agriculture and Rural Developmen

    - by me
    Author: Peter Reiser - Social Business Evangelist, Oracle WebCenter  Solution SummaryAlberta Agriculture and Rural Development is a government ministry that works with producers and consumers to create a strong, competitive, and sustainable agriculture and food industry in the province of Alberta, Canada The primary business challenge faced by the Alberta Ministry of Agriculture was that of managing the rapid growth of their information.  They needed to incorporate a system that would work across 22 different divisions within the ministry and deliver an improved and more efficient experience for Desktop, Web and Mobile users, while addressing their regulatory compliance needs as part of the Canadian government. The customer implemented a centralized Enterprise Content Management solution based on Oracle WebCenter Content and developed a strong and repeatable information life cycle management methodology across all their 22 divisions and agencies. With the implemented solution, Alberta Agriculture and Rural Development  centrally manages over 20 million documents for 22 divisions and agencies and they have improved time required to find records,  reliability of information, improved speed and accuracy of reporting and data security. Company OverviewAlberta Agriculture and Rural Development is a government ministry that works with producers and consumers to create a strong, competitive, and sustainable agriculture and food industry in the province of Alberta, Canada.  Business ChallengesThe business users were overwhelmed by growth in documents (over 20 million files across 22 divisions and agencies) and it was difficult to find and manage documents and versions. There was a strong need for a personalized easy-to-use, secure and dependable method of managing and consuming content via desktop, Web, and mobile, while improving efficiency and maintaining regulatory compliance by removing the risk of non-uniform approaches to retention and disposition. Solution DeployedAs a first step Alberta Agriculture and Rural Development developed a business case with clear defined business drivers: Reduce time required to find records Locate “lost” records Capture knowledge lost through attrition Increase the ease of retrieval Reduce personal copies Increase reliability of information Improve speed and accuracy of reporting Improve data security The customer implemented a centralized Enterprise Content Management solution based on Oracle WebCenter Content. They used an incremental implementation approach aligned with their divisional and agency structure which allowed continuous process improvement. This led to a very strong and repeatable information life cycle management methodology across all their 22 divisions and agencies. Business ResultsAlberta Agriculture and Rural Development achieved impressive business results: Centrally managing over 20 million files for 22 divisions and agencies Federated model to manage documents in SharePoint and other applications Doing records management for both paper and electronic records Reduced time required to find records Increased the ease of retrieval Increased reliability of information Improved speed and accuracy of reporting Improved data security Additional Information Oracle Open World 2012 Presentation Oracle WebCenter Content

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  • Implement Fast Inverse Square Root in Javascript?

    - by BBz
    The Fast Inverse Square Root from Quake III seems to use a floating-point trick. As I understand, floating-point representation can have some different implementations. So is it possible to implement the Fast Inverse Square Root in Javascript? Would it return the same result? float Q_rsqrt(float number) { long i; float x2, y; const float threehalfs = 1.5F; x2 = number * 0.5F; y = number; i = * ( long * ) &y; i = 0x5f3759df - ( i >> 1 ); y = * ( float * ) &i; y = y * ( threehalfs - ( x2 * y * y ) ); return y; }

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  • Getting started with object detection - Image segmentation algorithm

    - by Dev Kanchen
    Just getting started on a hobby object-detection project. My aim is to understand the underlying algorithms and to this end the overall accuracy of the results is (currently) more important than actual run-time. I'm starting with trying to find a good image segmentation algorithm that provide a good jump-off point for the object detection phase. The target images would be "real-world" scenes. I found two techniques which mirrored my thoughts on how to go about this: Graph-based Image Segmentation: http://www.cs.cornell.edu/~dph/papers/seg-ijcv.pdf Contour and Texture Analysis for Image Segmentation: http://www.eng.utah.edu/~bresee/compvision/files/MalikBLS.pdf The first one was really intuitive to understand and seems simple enough to implement, while the second was closer to my initial thoughts on how to go about this (combine color/intensity and texture information to find regions). But it's an order of magnitude more complex (at least for me). My question is - are there any other algorithms I should be looking at that provide the kind of results that these two, specific papers have arrived at. Are there updated versions of these techniques already floating around. Like I mentioned earlier, the goal is relative accuracy of image segmentation (with an eventual aim to achieve a degree of accuracy of object detection) over runtime, with the algorithm being able to segment an image into "naturally" or perceptually important components, as these two algorithms do (each to varying extents). Thanks! P.S.1: I found these two papers after a couple of days of refining my search terms and learning new ones relevant to the exact kind of techniques I was looking for. :) I have just about reached the end of my personal Google creativity, which is why I am finally here! Thanks for the help. P.S.2: I couldn't find good tags for this question. If some relevant ones exist, @mods please add them. P.S.3: I do not know if this is a better fit for cstheory.stackexchange (or even cs.stackexchange). I looked but cstheory seems more appropriate for intricate algorithmic discussions than a broad question like this. Also, I couldn't find any relevant tags there either! But please do move if appropriate.

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  • Geolocation through Android's GPS Provider on a website?

    - by Corey Ogburn
    I'm trying to get the geolocation of the mobile device in a regular website, not a webview of an application or anything native like that. I'm getting a location, but it's highly inaccurate, the accuracy comes back as 3230 or some other outrageous number. I'm assuming that's in meters, either way it's not nearly accurate enough. By comparison, the same webpage on a laptop gets an accuracy of 30-40. My first thought was that it was using the Network Provider instead of the GPS Provider, telling me where I am based on tower location and reach. A little research later I found enableHighAccuracy and set it true in the options that I pass. After including that, I still notice no difference. Here's the test page's HTML/javascript: <html> <head> <script type="text/javascript" src="http://ecn.dev.virtualearth.net/mapcontrol/mapcontrol.ashx?v=7.0"></script> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js"></script> <script type="text/javascript"> function OnLoad() { $("#Status").text("Init"); if (navigator.geolocation) { $("#Status").text("Supports Geolocation"); navigator.geolocation.getCurrentPosition(HandleLocation, LocationError, { enableHighAccuracy: true }); $("#Status").text("Sent position request..."); } else { $("#Status").text("Doesn't support geolocation"); } } function HandleLocation(position) { $("#Status").text("Received response:"); $("#Position").text("(" + position.coords.latitude + ", " + position.coords.longitude + ") accuracy: " + position.coords.accuracy); var loc = new Microsoft.Maps.Location(position.coords.latitude, position.coords.longitude); GetMap(loc); } function LocationError(error) { switch(error.code) { case error.PERMISSION_DENIED: alert("Location not provided"); break; case error.POSITION_UNAVAILABLE: alert("Current location not available"); break; case error.TIMEOUT: alert("Timeout"); break; default: alert("unknown error"); break; } } function GetMap(loc) { var map = new Microsoft.Maps.Map(document.getElementById("mapDiv"), {credentials: "Aj59meaCR1e7rNgkfQy7j08Pd3mzfP1r04hGesGmLe2a3ZwZ3iGecwPX2SNPWq5a", center: loc, mapTypeId: Microsoft.Maps.MapTypeId.road, zoom: 15}); } </script> </head> <body onload="javascript:OnLoad()"> <div id="Status"></div> <div id="Position"></div><br/> <div id='mapDiv' style="position:relative; width:600px; height:400px;"></div> </body> </html> I'm testing this on a rooted MyTouch 3G running Cyanogen 6.1 stable, Android 2.2 and GPS is enabled. In case rooting was a problem, I have also had various friends and coworkers try the webpage on their non-rooted 2.0+ Android devices. Each phone had various effects on the accuracy, but none were better than 1000, I attribute this to the different carriers. I have not (but eventually will) tested with iPhone or other location-aware cell phones.

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  • Overriding LINQ extension methods

    - by Ruben Vermeersch
    Is there a way to override extension methods (provide a better implementation), without explicitly having to cast to them? I'm implementing a data type that is able to handle certain operations more efficiently than the default extension methods, but I'd like to keep the generality of IEnumerable. That way any IEnumerable can be passed, but when my class is passed in, it should be more efficient. As a toy example, consider the following: // Compile: dmcs -out:test.exe test.cs using System; namespace Test { public interface IBoat { void Float (); } public class NiceBoat : IBoat { public void Float () { Console.WriteLine ("NiceBoat floating!"); } } public class NicerBoat : IBoat { public void Float () { Console.WriteLine ("NicerBoat floating!"); } public void BlowHorn () { Console.WriteLine ("NicerBoat: TOOOOOT!"); } } public static class BoatExtensions { public static void BlowHorn (this IBoat boat) { Console.WriteLine ("Patched on horn for {0}: TWEET", boat.GetType().Name); } } public class TestApp { static void Main (string [] args) { IBoat niceboat = new NiceBoat (); IBoat nicerboat = new NicerBoat (); Console.WriteLine ("## Both should float:"); niceboat.Float (); nicerboat.Float (); // Output: // NiceBoat floating! // NicerBoat floating! Console.WriteLine (); Console.WriteLine ("## One has an awesome horn:"); niceboat.BlowHorn (); nicerboat.BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // Patched on horn for NicerBoat: TWEET Console.WriteLine (); Console.WriteLine ("## That didn't work, but it does when we cast:"); (niceboat as NiceBoat).BlowHorn (); (nicerboat as NicerBoat).BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // NicerBoat: TOOOOOT! Console.WriteLine (); Console.WriteLine ("## Problem is: I don't always know the type of the objects."); Console.WriteLine ("## How can I make it use the class objects when the are"); Console.WriteLine ("## implemented and extension methods when they are not,"); Console.WriteLine ("## without having to explicitely cast?"); } } } Is there a way to get the behavior from the second case, without explict casting? Can this problem be avoided?

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  • Floats in CSS - Gap/space left on top when floated to the right?

    - by bobthabuilda
    This is a little difficult to describe, but basically there is undesired space left by a floated div on my page. Here are pictures describing the problem. The black boxes are divs. Before floating: After floating: Desired effect: And I'm not sure if it makes a difference, but I also have an empty div with "clear: both" placed immediately after the floated div. How can I achieve this?

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  • Can I have multiple colors in a single TextBlock in WPF?

    - by Siracuse
    I have a line of text in a textblock that reads: "Detected [gesture] with an accuracy of [accuracy]" In WPF, is it possible for me to be able to change the color of the elements within a textblock? Can I have a textblock be multiple colors? For example, I would like the whole TextBlock to be black except the gesture name, which I would like to be red. Is this possible in WPF?

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  • Cepstral Analysis for pitch detection

    - by Ohmu
    Hi! I'm looking to extract pitches from a sound signal. Someone on IRC just explain to me how taking a double FFT achieves this. Specifically: take FFT take log of square of absolute value (can be done with lookup table) take another FFT take absolute value I am attempting this using vDSP I can't understand how I didn't come across this technique earlier. I did a lot of hunting and asking questions; several weeks worth. More to the point, I can't understand why I didn't think of it. I am attempting to achieve this with vDSP library. it looks as though it has functions to handle all of these tasks. However, I'm wondering about the accuracy of the final result. I have previously used a technique which scours the frequency bins of a single FFT for local maxima. when it encounters one, it uses a cunning technique (the change in phase since the last FFT) to more accurately place the actual peak within the bin. I am worried that this precision will be lost with this technique I'm presenting here. I guess the technique could be used after the second FFT to get the fundamental accurately. But it kind of looks like the information is lost in step 2. as this is a potentially tricky process, could someone with some experience just look over what I'm doing and check it for sanity? also, I've heard there is an alternative technique involving fitting a quadratic over neighbouring bins. Is this of comparable accuracy? if so, I would favour it, as it doesn't involve remembering bin phases. so questions: does this approach makes sense? Can it be improved? I'm a bit worried about And the log square component; there seems to be a vDSP function to do exactly that: vDSP_vdbcon however, there is no indication it precalculates a log-table -- I assume it doesn't, as the FFT function requires an explicit pre-calculation function to be called and passed into it. and this function doesn't. Is there some danger of harmonics being picked up? is there any cunning way of making vDSP pull out the maxima, biggest first? Can anyone point me towards some research or literature on this technique? the main question: is it accurate enough? Can the accuracy be improved? I have just been told by an expert that the accuracy IS INDEED not sufficient. Is this the end of the line? Pi PS I get SO annoyed (npi) when I want to create tags, but cannot. :| I have suggested to the maintainers that SO keep track of attempted tags, but I'm sure I was ignored. we need tags for vDSP, accelerate framework, cepstral analysis

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  • Visual Studio 2008 - Why do my windows keep rearranging themselves?

    - by nailitdown
    Every so often (at least a couple of times a day), my VS2008 windows are rearranging themselves. Team/Solution/Server Explorer - They jump from the right sidebar down to the bottom, or suddenly become free-floating. Same with Errors/Pending Changes/etc. free-floating or suddenly gone, as if they've been closed. It is very strange behaviour. Has anyone else experienced it? Am I doing something silly that would account for this?

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  • Python: convert 2 ints to 32 float

    - by bugspy.net
    How can I combine 2 ints to a single 32bit IEEE floating point ? (each of the 2 ints represent 16 bit) And in the opposite direction: How can I transform a python float into 2 16 bit ints? (I need this because of modbus protocol - where 2x16 bit registers are treated as single 32 floating point number)

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  • Float addition promoted to double?

    - by Andreas Brinck
    I had a small WTF moment this morning. Ths WTF can be summarized with this: float x = 0.2f; float y = 0.1f; float z = x + y; assert(z == x + y); //This assert is triggered! (Atleast with visual studio 2008) The reason seems to be that the expression x + y is promoted to double and compared with the truncated version in z. (If i change z to double the assert isn't triggered). I can see that for precision reasons it would make sense to perform all floating point arithmetics in double precision before converting the result to single precision. I found the following paragraph in the standard (which I guess I sort of already knew, but not in this context): 4.6.1. "An rvalue of type float can be converted to an rvalue of type double. The value is unchanged" My question is, is x + y guaranteed to be promoted to double or is at the compiler's discretion? UPDATE: Since many people has claimed that one shouldn't use == for floating point, I just wanted to state that in the specific case I'm working with, an exact comparison is justified. Floating point comparision is tricky, here's an interesting link on the subject which I think hasn't been mentioned.

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