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  • How would i down-sample a .wav file then reconstruct it using nyquist? - in matlab [closed]

    - by martin
    Possible Duplicate: How would i down-sample a .wav file then reconstruct it using nyquist? - in matlab This is all done in MatLab 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the various sampling at different frequencies?

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  • Load dll's from Environment Variable Path from a service

    - by Paulo Manuel Santos
    We install Matlab Runtime on a machine, then we restart a .net windows service that invokes methods from the Matlab Runtime. The problem is that we receive TypeInitializationException errors until we restart windows. We think this happens because Environment Variables are not changed on services until restart and Matlab uses the %Path% variable to reference it's core DLL's. My question is, do you think I can change the %Path% variable so that Matlab will use it when referencing the core dll's for it's engine? Or is it possible to add a directory to the runtime DLL loading mechanism of .NET so that those Matlab core dll's would be referenced correctly without restarting the machine? Here is the exception we get System.TypeInitializationException: The type initializer for 'MatlabCalculation.Calculation' threw an exception. ---> System.TypeInitializationException: The type initializer for 'MathWorks.MATLAB.NET.Utility.MWMCR' threw an exception. ---> System.DllNotFoundException: Unable to load DLL 'mclmcrrt710.dll': Kan opgegeven module niet vinden. (Exception from HRESULT: 0x8007007E) at MathWorks.MATLAB.NET.Utility.MWMCR.mclmcrInitialize() at MathWorks.MATLAB.NET.Utility.MWMCR..cctor() --- End of inner exception stack trace --- at MatlabCalculation.Calculation..cctor() --- End of inner exception stack trace --- at MatlabCalculation.Calculation.Finalize() "Kan opgegeven module niet vinden" = "The specified module not found"

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  • Faster method for Matrix vector product for large matrix in C or C++ for use in GMRES

    - by user35959
    I have a large, dense matrix A, and I aim to find the solution to the linear system Ax=b using an iterative method (in MATLAB was the plan using its built in GMRES). For more than 10,000 rows, this is too much for my computer to store in memory, but I know that the entries in A are constructed by two known vectors x and y of length N and the entries satisfy: A(i,j) = .5*(x[i]-x[j])^2+([y[i]-y[j])^2 * log(x[i]-x[j])^2+([y[i]-y[j]^2). MATLAB's GMRES command accepts as input a function call that can compute the matrix vector product A*x, which allows me to handle larger matrices than I can store in memory. To write the matrix-vecotr product function, I first tried this in matlab by going row by row and using some vectorization, but I avoid spawning the entire array A (since it would be too large). This was fairly slow unfortnately in my application for GMRES. My plan was to write a mex file for MATLAB to, which is in C, and ideally should be significantly faster than the matlab code. I'm rather new to C, so this went rather poorly and my naive attempt at writing the code in C was slower than my partially vectorized attempt in Matlab. #include <math.h> #include "mex.h" void Aproduct(double *x, double *ctrs_x, double *ctrs_y, double *b, mwSize n) { mwSize i; mwSize j; double val; for (i=0; i<n; i++) { for (j=0; j<i; j++) { val = pow(ctrs_x[i]-ctrs_x[j],2)+pow(ctrs_y[i]-ctrs_y[j],2); b[i] = b[i] + .5* val * log(val) * x[j]; } for (j=i+1; j<n; j++) { val = pow(ctrs_x[i]-ctrs_x[j],2)+pow(ctrs_y[i]-ctrs_y[j],2); b[i] = b[i] + .5* val * log(val) * x[j]; } } } The above is the computational portion of the code for the matlab mex file (which is slightly modified C, if I understand correctly). Please note that I skip the case i=j, since in that case the variable val will be a 0*log(0), which should be interpreted as 0 for me, so I just skip it. Is there a more efficient or faster way to write this? When I call this C function via the mex file in matlab, it is quite slow, slower even than the matlab method I used. This surprises me since I suspected that C code should be much faster than matlab. The alternative matlab method which is partially vectorized that I am comparing it with is function Ax = Aprod(x,ctrs) n = length(x); Ax = zeros(n,1); for j=1:(n-3) v = .5*((ctrs(j,1)-ctrs(:,1)).^2+(ctrs(j,2)-ctrs(:,2)).^2).*log((ctrs(j,1)-ctrs(:,1)).^2+(ctrs(j,2)-ctrs(:,2)).^2); v(j)=0; Ax(j) = dot(v,x(1:n-3); end (the n-3 is because there is actually 3 extra components, but they are dealt with separately,so I excluded that code). This is partly vectorized and only needs one for loop, so it makes some sense that it is faster. However, I was hoping I could go even faster with C+mex file. Any suggestions or help would be greatly appreciated! Thanks! EDIT: I should be more clear. I am open to any faster method that can help me use GMRES to invert this matrix that I am interested in, which requires a faster way of doing the matrix vector product without explicitly loading the array into memory. Thanks!

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  • Finding the Twins when Implementing Catmull-Clark subdivision using Half-Edge mesh [migrated]

    - by Ailurus
    Note: The description became a little longer than expected. Do you know a readable implementation of this algorithm using this mesh? Please let me know! I'm trying to implement Catmull-Clark subdivision using Matlab (because later on the results have to be compared with some other stuff already implemented in Matlab). First try was with a Vertex-Face mesh, the algorithm works but it is of course not very efficient (since you need neighbouring information for edges and faces). Therefore, I'm now using a Half-Edge mesh (info), see also the paper of Lutz Kettner. Wikipedia link to the idea behind Catmull-Clark SDV: Wiki. My problem lies in finding the Twin HalfEdges, I'm just not sure how to do this. Below I'm describing my thoughts on the implementation, trying to keep it concise. Half-Edge mesh (using indices to Vertices/HalfEdges/Faces): Vertex (x,y,z,Outgoing_HalfEdge) HalfEdge (HeadVertex (or TailVertex, which one should I use), Next, Face, Twin). Face (HalfEdge) To keep it simple for now, assume that every face is a quadrilateral. The actual mesh is a list of Vertices, HalfEdges and Faces. The new mesh will consist of NewVertices, NewHalfEdges and NewFaces, like this (note: Number_... is the number of ...): NumberNewVertices: Number_Faces + Number_HalfEdges/2 + Number_Vertices NumberNewHalfEdges: 4 * 4 * NumberFaces NumberNewfaces: 4 * NumberFaces Catmull-Clark: Find the FacePoint (centroid) of each Face: --> Just average the x,y,z values of the vertices, save as a NewVertex. Find the EdgePoint of each HalfEdge: --> To prevent duplicates (each HalfEdge has a Twin which would result in the same HalfEdge) --> Only calculate EdgePoints of the HalfEdge which has the lowest index of the Pair. Update old Vertices Ok, now all the new Vertices are calculated (however, their Outgoing_HalfEdge is still unknown). Next step to save the new HalfEdges and Faces. This is the part causing me problems! Loop through each old Face, there are 4 new Faces to be created (because of the quadrilateral assumption) First create the 4 new HalfEdges per New Face, starting at the FacePoint to the Edgepoint Next a new HalfEdge from the EdgePoint to an Updated Vertex Another new one from the Updated Vertex to the next EdgePoint Finally the fourth new HalfEdge from the EdgePoint back to the FacePoint. The HeadVertex of each new HalfEdge is known, the Next HalfEdge too. The Face is also known (since it is the new face you're creating!). Only the Twin HalfEdge is unknown, how should I know this? By the way, while looping through the Vertices of the new Face, assign the Outgoing_HalfEdge to the Vertices. This is probably the place to find out which HalfEdge is the Twin. Finally, after the 4 new HalfEdges are created, save the Face with the HalfVertex index the last newly created HalfVertex. I hope this is clear, if needed I can post my (obviously not-yet-finished) Matlab code.

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  • Matlab postpones disp calls when doing demanding calculations why is that?

    - by Reed Richards
    I am implementing an algorithm in Matlab. Among other things it calculates shortest paths etc. so its quite demanding for my old computer. I've put out disp calls through out the program to see what's happening all the time. However when starting on a particulary heavy for loop the disp seemes not to be called until the loop is over even though it comes before the loop. Why is that? I though that Matlab was really linear or am I just choking it with to many calculations and the disp calls get the lowest priority?

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  • How to convert a C++ program that uses CUDA into MEX

    - by Harold Wellington Graves
    For work, I am converting the Image Denoising program that comes with the CUDA SDK into a MATLAB program. As far as I know, I have made all the necessary changes required by MATLAB, but when I try to call mex on it, MATLAB returns a bunch of linkage errors that I have no idea how to fix. If anyone has any suggestions on what I might be doing wrong, I would greatly appreciate it. The command I am giving MATLAB is: mex imageDenoisingGL.cpp -I..\..\common\inc -IC:\CUDA\include -L..\..\common\lib -lglut32 And the output from MATLAB is a bunch of these: imageDenoisingGL.obj : error LNK2019: unresolved external symbol __imp__cutCheckCmdLineFlag@12 referenced in function "void __cdecl __cutilExit(int,char * *)" (?__cutilExit@@YAXHPAPAD@Z) I am running: Windows XP x32 Visual Studio 2005 MATLAB 2007a

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  • How do you write multiple lists from Matlab to the same excel file?

    - by Ben Fossen
    I have several lists in Matlab that I want to write to the same excel file. I have one list xordered and another list aspl. I do not know the length of the lists till after I run the Matlab program. I used data = xlswrite('edgar.xls',fliplr(sortedx'),'A2:A3000') for the first list but when I tried to write another list to the same file like this I ended up with two different excel files named edgar.xls asp_data = xlswrite('edagr.xls', fliplr(aspl'), 'B2:B3000') Is there a way I can write both of these lists into the same excel file? xordered in the A column and aspl in the B column?

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  • How do you pass in a value to a subfunction in Matlab I am getting output errors?

    - by Ben Fossen
    Below is my code in Matlab I am having trouble with the line sum = (h/2) * (f(a) + f(b)) + h; Matlab says I have to many outputs when I try to call the f(x) function. Is my problem with the f(x) function function Trapezoid_Uniform(a,b,n) h = (b - a)/n; sum = (h/2) * (f(a) + f(b)) + h; for i = 1:n-1 x = a + i*h; sum = sum + f(x); end sum = sum*h; disp(sum); end function f(z) f = exp(z); end

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  • Realy urgent and big help in a little MATLAB game... Please help me!

    - by Sanyi
    Hi! I have to make the game „Planarity” in Matlab, for school project. (If you Google it, you can see and play the game in flash). The computer have to randomly put 5 circles in the coordinate system in different positions. After that it must draw lines between them. When the circles are randomly put in the coordinate system the coordinates must be whole numbers. Good example for number one circle: (3,4) ; bad example for number one circle (2.5 ,6.7). Please if Matlab is a childs game to you help me by sending me the source code for this. I really really need help... Please help me, this can be one hour to you, but a life saving thing to me...

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  • can i changed for loop index variable inside the loop in Matlab???

    - by shawana
    hi every one. i need to change my loop variable inside the iterationa as ihave to acces array elements in the loop which is changing w.r.t size inside the loop. ashort piece of code is that: que=[]; que=[2,3,4]; global len; len=size(que,2) x=4; for i=1:len if x<=10 que(x)= 5; len=size(que,2) x=x+1; end end que array should print like: 2 3 4 5 5 5 5 5 5 5 but it is printed in such a way: 2 3 4 5 5 5. how shuould it be accomplished in matlab? in visual c++ it happen correctly and print whole array of 10 elements which increases at run time plz reply me if have any ideaabout this as i m new into matlab

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  • Packaging MATLAB (or, more generally, a large binary, proprietary piece of software)

    - by nfirvine
    I'm trying to package MATLAB for internal distribution, but this could apply to any piece of software with the same architecture. In fact, I'm packaging multiple releases of MATLAB to be installed concurrently. Key things Very large installation size (~4 GB) Composed of a core, and several plugins (toolboxes) Initially, I created a single "source" package (matlab2011b) that builds several .debs (mainly matlab2011b-core and matlab2011b-toolbox-* for each toolbox). The control file is just the standard all: dh $@ There is no Makefile; only copying files. I use a number of debian/*.install files to specify files to copy from a copy of an installation to /usr/lib/. The problem is, every time I build the thing (say, to make a correction to the core package), it recopies every file listed in the *.install file to e.g debian/$packagename/usr/ (the build phase), and then has to bundle that into a .deb file. It takes a long time, on the order of hours, and is doing a lot of extra work. So my questions are: Can you make dh_install do a hardlink copy (like cp -l) to save time? (AFAICT from the man page, no.) Maybe I should just get it to do this in the Makefile? (That's gonna b e big Makefile.) Can you make debuild only rebuild .debs that need rebuilding? Or specify which .debs to rebuild? Is my approach completely stupid? Should I break each of the toolboxes into its own source package too? (I'll have to do some silly templating or something, because there's hundreds of them. :/)

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  • Trying to sort the coefficients of the polynomial (z-a)(z-b)(z-c)...(z-n) into a vector

    - by pajamas
    So I have a factored polynomial of the form (z-a)(z-b)(z-c)...(z-n) for n an even positive integer. Thus the coefficient of z^k for 0 <= k < n will be the sum of all distinct n-k element products taken from the set {a,b,...,n} multiplied by (-1)^k, I hope that makes sense, please ask if you need more clarification. I'm trying to put these coefficients into a row vector with the first column containing the constant coefficient (which would be abc...n) and the last column containing the coefficient for z^n (which would be 1). I imagine there is a way to brute force this with a ton of nested loops, but I'm hoping there is a more efficient way. This is being done in Matlab (which I'm not that familiar with) and I know Matlab has a ton of algorithms and functions, so maybe its got something I can use. Can anyone think of a way to do this? Example: (z-1)(z-2)(z-3) = z^3 - (1 + 2 + 3)z^2 + (1*2 + 1*3 + 2*3)z - 1*2*3 = z^3 - 6z^2 + 11z - 6. Note that this example is n=3 odd, but n=4 would have taken too long to do by hand. Edit: Let me know if you think this would be better posted at TCS or Math Stack Exchange.

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  • How to load toolbox items of different domain specific languages

    - by Tejas
    I have 'n' different domain specifc languages e.g. language1, language2, ...., languagen each of which contains different toolbox items. Let say first language is for banking process, second one is for health process, third one is for insurance process etc. I want to load toolbox items of every above mentioned languages into every language. i.e. the toolbox item defined in banking process should be visible and functional in all other languages i.e. inside health and insurance languages resp.

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  • Could not determine the size of this expression.

    - by Søren
    Hi, I have resently started to use MATLAB Simulink, and my problem is that i can't implement an AMDF function, because simulink compiler cannot determine the lengths. Simulink errors: |--------------------------------------------------------------------------------------- Could not determine the size of this expression. Function 'Embedded MATLAB Function2' (#38.728.741), line 33, column 32: "1:flength-k+1" Errors occurred during parsing of Embedded MATLAB function 'Embedded MATLAB Function2'(#38) Embedded MATLAB Interface Error: Errors occurred during parsing of Embedded MATLAB function 'Embedded MATLAB Function2'(#38) . |--------------------------------------------------------------------------------------- MY CODE: |--------------------------------------------------------------------------------------- persistent sLength persistent fLength persistent amdf % Length of the frame flength = length(frame); % Pitch period is between 2.5 ms and 19.5 ms for LPC-10 algorithm % This because this algorithm assumes the frequencyspan is 50 and 400 Hz pH = ceil((1/min(fspan))*fs); if(pH flength) pH = flength; end; pL = ceil((1/max(fspan))*fs); if(pL <= 0 || pL = flength) pL = 0; end; sLength = pH - pL; % Normalize the frame frame = frame/max(max(abs(frame))); % Allocating memory for the calculation of the amdf %amdf = zeros(1,sLength); %%%%%%%% amdf = 0; % Calculating the AMDF with unbiased normalizing for k = (pL+1):pH amdf(k-pL) = sum(abs(frame(1:flength-k+1) - frame(k:flength)))/(flength-k+1); end; % Output of the AMDF if(min(amdf) < lvlThr) voiced = 1; else voiced = 0; end; % Output of the minimum of the amdf minAMDF = min(amdf); |---------------------------------------------------------------------------------------- HELP Kind regards Søren

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  • How would i down-sample a .wav file then reconstruct it using nyquist? - in MATLAB

    - by Andrew
    This is all done in MATLAB 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the sampling at verious frequencies?

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  • Toolbox for Computer Hardware

    - by Chuy77
    I have a lot of computer hardware (hard drives, cables, etc.) and I need a better way to organize. Could anyone recommend a toolbox intended for this sort of thing, or some other good method for storage? I have a two drawer wide file that I currently use, with large plastic bags. It works okay, but I need a better system. Thanks for any advice.

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  • Matlab GUI - How to get the previous value entered from a callback function?

    - by Graham
    Hi, I know that this is probably a simple problem but I am new to Matlab GUI's and basically want to get the old value which used to be stored in the text box to replace the value which has just been entered. E.g. Text box contains a valid string, User enters invalid string, Callback func, validates input and realises new input is an error and reverts to the old previous value. How should this be implemented or done? Atm I am just using the get and set property values. Below is some sample code: function sampledist_Callback(hObject, eventdata, handles) % hObject handle to sampledist (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) % Hints: get(hObject,'String') returns contents of sampledist as text % str2double(get(hObject,'String')) returns contents of sampledist as a double input = str2double(get(hObject,'String')); if(input < 0 || input > 500) errordlg('Sampled Dist. must be > 0 and < 500','Sample Dist - Input Error'); set(handles.sampledist,'String',['10']); %<--- I would like this value 10 to be the previous entry! guidata(hObject,handles); else set(handles.sampledist,'String',['',input]); guidata(hObject,handles); end

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  • How to get SharePoint 2010 controls in toolbox

    - by Suja Shyam
    My application uses Visual Studio 2010 to develop an application in SharePoint 2010. I created a visual webpart and added a <SharePoint:SPCalendarView ID="EventsCalendar1" width="100%" runat="server"></SharePoint:SPCalendarView> I also found that there are many other controls which appears in intellisense. How can I add these controls to the toolbox? Is there any documentation available on how to use these controls?

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  • Bring Control to ToolBox

    - by Mohanavel
    I created a TextBoxControl which is inherited from Infragistics.Win.UltraWinEditors.UltraTextEditor, an Infragistics control. As showed below. public class TextBoxControl : Infragistics.Win.UltraWinEditors.UltraTextEditor { //My Stuff } At some level Infragistics.Win.UltraWinEditors.UltraTextEditor class also inherited from WinForm's "Control" class. My problem is, this control is not appearing in the ToolBox. I done two steps 1. Choose from browse option and select the dll where the class present 2. Drag and drop the dll directly to the ToolBox In-fact both are same, TextBoxControl control is not appearing in the ToolBox, what i missing here. Edit : TextBoxControl class have empty constructor, nothing special in this class.

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  • ASP.NET 2.0 control is not shown up un VS 2010 toolbox

    - by user353653
    Hi, I have developed some ASP.NET controls in .NET 2.0 with VS 2008. Now, I upgraded my project to VS 2010 but did not change the target framework to .NET 4.0 yet. But, surprisingly, I found that, the toolbox is not showing the bitmaps for the control added to the toolbox in VS 2010. Moreover, when I dragged and dropped a control (.NET 2.0) from the toolbox to my Web Form, I see some junk xml code added to my web form. I dont know if I need to recompile the .NET 2.0 controls with VS 2010 ? or what should I do in order to make the controls compatible for both in VS 2008 and VS 2010 ? I found that, there is no problem with Windows Forms control, rather it is just with ASP.NET Controls.

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