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  • Extrapolation using fft in octave

    - by CFP
    Using GNU octave, I'm computing a fft over a piece of signal, then eliminating some frequencies, and finally reconstructing the signal. This give me a nice approximation of the signal ; but it doesn't give me a way to extrapolate the data. Suppose basically that I have plotted three periods and a half of f: x -> sin(x) + 0.5*sin(3*x) + 1.2*sin(5*x) and then added a piece of low amplitude, zero-centered random noise. With fft/ifft, I can easily remove most of the noise ; but then how do I extrapolate 3 more periods of my signal data? (other of course that duplicating the signal). The math way is easy : you have a decomposition of your function as an infinite sum of sines/cosines, and you just need to extract a partial sum and apply it anywhere. But I don't quite get the programmatic way... Thanks!

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  • Daubechies-4 Transform in MATLAB

    - by Myx
    Hello: I have a 4x4 matrix which I wish to decompose into 4 frequency bands (LL, HL, LH, HH where L=low, H=high) by using a one-level Daubechies-4 wavelet transform. As a result of the transform, each band should contain 2x2 coefficients. How can I do this in MATLAB? I know that MATLAB has dbaux and dbwavf functions. However, I'm not sure how to use them and I also don't have the wavelet toolbox. Any help is greatly appreciated. Thanks.

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  • Is a VCS appropriate for usage by a designer?

    - by iconiK
    I know that a VCS is absolutely critical for a developer to increase productivity and protect the code, no doubts about it. But what about a designer, using say, Photoshop (though it's not specific to any tools, just to make my point clearer). VCSs uses delta compression to store different versions of files. This works very well for code, but for images, that's a problem. Raster image files are binary formats, though vector image files are text (SVG comes to my mind) and pose to problem. The problem comes with .psd files (and any other image "source" file) - those can get pretty big and since I'm not familiar with the format, I'll consider them as binary files. How would a VCS work in this condition? The repository could be pretty darned big if the VCS server isn't able to diff the files efficiently (or worse, not at all) and over time this can become a really big pain when someone needs to check out the repository (or clone it if using a DVCS). Have any of you used a VCS for this purpose? How well does it work? I'm mostly interested in Mercurial, though this is a general situation that applies to any VCS.

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  • Simplex noise vs Perlin noise

    - by raRaRa
    I would like to know why Perlin noise is still so popular today after Simplex came out. Simplex noise was made by Ken Perlin himself and it was suppose to take over his old algorithm which was slow for higher dimensions and with better quality (no visible artifacts). Simplex noise came out in 2001 and over those 10 years I've only seen people talk of Perlin noise when it comes to generating heightmaps for terrains, creating procedural textures, et cetera. Could anyone help me out, is there some downside of Simplex noise? I heard rumors that Perlin noise is faster when it comes to 1D and 2D noise, but I don't know if it's true or not. Thanks!

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  • How to add a URL and Buttons on top of an Existing Header Image

    - by tonsils
    Hi, 1) I have a header jpeg image that spans a width of 996px that has a square logo to the left of this header. My question is that I would like to use this square logo section only and place a ahref tag so that when the user hover's over this section only, the cursor changes to a hand pointer and the user will be redirected back to the landing page. Any assistance on this would be great. 2) On this same image, I would also like to place two buttons with rollover effects, so when the user hovers over the buttons, the rollover effect takes control and then would like these buttons to also point to a href url. Again, any help on this would be appreciated. Thanks.

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  • TMS320C64x Quick start reference for porgrammers

    - by osgx
    Hello Is thare any quickstart guide for programmers for writing DSP-accelerated appliations for TMS320C64x? I have a program with custom algorythm (not the fft, or usial filtering) and I want to accelerate it using multi-DSP coprocessor. So, how should I modify source to move computation from main CPU to DSPs? What limitations are there for DSP-running code? I have some experience with CUDA. In CUDA I should mark every function as being host, device, or entry point for device (kernel). There are also functions to start kernels and to upload/download data to/from GPU. There are also some limitations, for device code, described in CUDA Reference manual. I hope, there is an similar interface and a documentation for DSP.

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  • StackOverFlowException - but oviously NO recursion/endless loop

    - by user567706
    Hi there, I'm now blocked by this problem the entire day, read thousands of google results, but nothing seems to reflect my problem or even come near to it... i hope any of you has a push into the right direction for me. I wrote a client-server-application (so more like 2 applications) - the client collects data about his system, as well as a screenshot, serializes all this into a XML stream (the picture as a byte[]-array]) and sends this to the server in regular intervals. The server receives the stream (via tcp), deserializes the xml to an information-object and shows the information on a windows form. This process is running stable for about 20-25 minutes at a submission interval of 3 seconds. When observing the memory usage there's nothing significant to see, also kinda stable. But after these 20-25 mins the server throws a StackOverflowException at the point where it deserializes the tcp-stream, especially when setting the Image property from the byte[]-array. I thoroughly searched for recursive or endless loops, and regarding the fact that it occurs after thousands of sucessfull intervals, i could hardly imagine that. public byte[] ImageBase { get { MemoryStream ms = new MemoryStream(); _screen.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); return ms.GetBuffer(); } set { if (_screen != null) _screen.Dispose(); //preventing well-known image memory leak MemoryStream ms = new MemoryStream(value); try { _screen = Image.FromStream(ms); //<< EXCEPTION THROWING HERE } catch (StackOverflowException ex) //thx to new CLR management this wont work anymore -.- { Console.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace); } ms.Dispose(); ms = null; } } I hope that more code would be unnecessary, or it could get very complex... Please help, i have no clue at all anymore thx Chris

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  • C# manipulating video

    - by grey88
    i want to take a folder of pictures, and turn it into a slideshow video with music in the background. i have no idea how to do this, or where to get help, cos this isnt the kind of thing you can search in google. idk if there are api's for it, or if it can even be done in C#. maybe ill have to move the project to C++ or something, but first i need to know where the hell to start. thanks.

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  • Copy & rename file using .bat file language?

    - by flyout
    I want to make a .bat to copy & rename a file multiple times. I want to have a list of names, and an original file, then I want to copy that file and rename it for each name on the list. How I can do this using a .bat file? Also is it possible to run winrar fromthe .bat to .rar or .zip every file after copying/renaming?

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  • convert RGB values to equivalent HSV values using python

    - by sree01
    Hi, I want to convert RGB values to HSV using python. I got some code samples, which gave the result with the S and V values greater than 100. (example : http://code.activestate.com/recipes/576554-covert-color-space-from-hsv-to-rgb-and-rgb-to-hsv/ ) . anybody got a better code which convert RGB to HSV and vice versa thanks

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  • perl multiple tasks problem

    - by Alice Wozownik
    I have finished my earlier multithreaded program that uses perl threads and it works on my system. The problem is that on some systems that it needs to run on, thread support is not compiled into perl and I cannot install additional packages. I therefore need to use something other than threads, and I am moving my code to using fork(). This works on my windows system in starting the subtasks. A few problems: How to determine when the child process exits? I created new threads when the thread count was below a certain value, I need to keep track of how many threads are running. For processes, how do I know when one exits so I can keep track of how many exist at the time, incrementing a counter when one is created and decrementing when one exits? Is file I/O using handles obtained with OPEN when opened by the parent process safe in the child process? I need to append to a file for each of the child processes, is this safe on unix as well. Is there any alternative to fork and threads? I tried use Parallel::ForkManager, but that isn't installed on my system (use Parallel::ForkManager; gave an error) and I absolutely require that my perl script work on all unix/windows systems without installing any additional modules.

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  • How to overwirte i-frames of a video?

    - by Dominik
    hi, i want to destroy alle i-frames of a video. doing this i want to check if encrypting only the i-frames of a video would be sufficient for making it unwatchable. How can i do this? Only removing them and recompressing the video would not be the same as really overwriting the iframe in the stream without recalculating b-frames etc.

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  • Touch area changing on custom UIButton with image and title on landscape mode

    - by gkedmi
    hello all I'm trying to build a button that looks like the icons on the iphone , with an image and a title bellow.I'm working in landscape mode. I have a custom button on the IB with image and title and inside the code I use the methods : [aButton setTitleEdgeInsets:UIEdgeInsetsMake(60.0, -50.0, 0.0, 0.0)]; [aButton setImageEdgeInsets:UIEdgeInsetsMake(-10.0, 29.0, 0.0, 0.0)]; my problem is that the area that react to the touch events is very small and is on the top left of the button , another problem is that if I change my button size I have to calculate again manually the values for these 2 functions. Is there any easy way to do it?and if not how can I fix the touch area? thanks Gilad

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  • Help needed in Javascript + Image + HREF

    - by Bragaadeesh
    Hi, <a href="#"><img src="http://www.google.com/intl/en_ALL/images/logo.gif" onClick="alert('hi')"/></a> In the above code, i am appending a javascript onclick method to the image tag. When I click the image once and I press back, it should go back to the page it came from. Instead its staying on the same page. Is there any way I can avoid that? (probably set something else instead of href="#"). The reason I set href="#" is to make my cursor turn into hand, other than that it has no use. This is occuring in FIREFOX, IE it works fine Please help. Thanks.

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  • How to overwrite i-frames of a video?

    - by Dominik
    I want to destroy all i-frames of a video. Doing this I want to check if encrypting only the i-frames of a video would be sufficient for making it unwatchable. How can I do this? Only removing them and recompressing the video would not be the same as really overwriting the i-frame in the stream without recalculating b-frames etc.

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  • Image animation over CGContextDrawPDFPage

    - by BittenApple
    I have a pdf page displayed with CGContextDrawPDFPage in QuartzDemo sample application. I want to keep this page shown and have an image slide in from top over this page, just as it can be seen in the iBooks application. It's a book, the sliding image is a bookmark that slides in when you are about to close the book. I added this code by DyingCactus (hint: im a newbie to obj c and iphone dev) as follows: In QuartzViewController.m, the animation starts to show but the view slides away before the animation is finished, in fact I think the animation goes on while the view is sliding away. -(void)viewWillDisappear:(BOOL)animated { [self.quartzView setFrame:CGRectMake(150, -200, 100, 200)]; [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:1.0]; [self.quartzView setFrame:CGRectMake(150, 0, 100, 200)]; [UIView commitAnimations]; } How can I keep the view visible and finish the animation before view disappears?

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  • Why aren't APT generated classes being compiled by Eclipse?

    - by yamsha
    In my Eclipse project I'm using a third-party annotation processor, Hibernate Metamodel Generator to be exact. The annotation processor works as expected and generates files as specified by the spec. These files are generated inside the directory of the Eclipse project under a "gen" folder. In the project properties this is correctly reflected since two source folders exist - "src" and "gen." However, when the project is built for some reason all the [generated] sources under "gen" are not compiled (checking the "bin" directory I only see .class file from the "src" directory). Does anyone know why this is happening?

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  • Shared value in parallel python

    - by Jonathan
    Hey all- I'm using ParallelPython to develop a performance-critical script. I'd like to share one value between the 8 processes running on the system. Please excuse the trivial example but this illustrates my question. def findMin(listOfElements): for el in listOfElements: if el < min: min = el import pp min = 0 myList = range(100000) job_server = pp.Server() f1 = job_server.submit(findMin, myList[0:25000]) f2 = job_server.submit(findMin, myList[25000:50000]) f3 = job_server.submit(findMin, myList[50000:75000]) f4 = job_server.submit(findMin, myList[75000:100000]) The pp docs don't seem to describe a way to share data across processes. Is it possible? If so, is there a standard locking mechanism (like in the threading module) to confirm that only one update is done at a time? l = Lock() if(el < min): l.acquire if(el < min): min = el l.release I understand I could keep a local min and compare the 4 in the main thread once returned, but by sharing the value I can do some better pruning of my BFS binary tree and potentially save a lot of loop iterations. Thanks- Jonathan

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