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  • GPIB connection to external device using MATLAB

    - by hkf
    Is there a way to establish a GPIB connection using MATLAB without the instrument control Tool box? (I don't have it). Also is there a way for MATLAB to know what the external device's RS232 parameter values are ( Baud rate, stop bit etc..). For the RS232 connection I have the following code: % This function is meant to send commands to Potentiostat Model 263A. % A run includes turning the cell on, reading current for time t1, turning % the cell off, waiting for time t2. % t1 is the duration [secs] for which the Potentiostat must run (cell is on) % t2 is the duration [secs] to on after off % n is the number of runs % port is the serial port name such as COM1 function [s] = Potentiostat_control(t1,t2,n) port = input('type port name such as COM1', 's') s = serial(port); set(s,'BaudRate', 9600, 'DataBits', 8, 'Parity', 'even', 'StopBits', 2 ,'Terminator', 'CR/LF'); fopen(s) %fprintf(s,'RS232?') disp(['Total runs requested = ' num2str(n)]) disp('i denotes number of runs executed so far..'); for i=1:n i %data1 = query(s, '*IDN?') fprintf(s,'%s','CELL 1'); % sends the command 'CELL 1' %fprintf(s,'%s','READI'); pause(t1); fprintf(s,'%s','CELL 0'); %fprintf(s,'%s','CLEAR'); pause(t2); end fclose(s)

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  • Calculate posterior distribution of unknown mis-classification with PRTools in MATLAB

    - by Samuel Lampa
    I'm using the PRTools MATLAB library to train some classifiers, generating test data and testing the classifiers. I have the following details: N: Total # of test examples k: # of mis-classification for each classifier and class I want to do: Calculate and plot Bayesian posterior distributions of the unknown probabilities of mis-classification (denoted q), that is, as probability density functions over q itself (so, P(q) will be plotted over q, from 0 to 1). I have that (math formulae, not matlab code!): P(q|k,N) = Posterior * Prior / Normalization constant = P(k|q,N) * P(q|N) / P(k|N) The prior is set to 1, so I only need to calculate the posterior and normalization constant. I know that the posterior can be expressed as (where B(N,k) is the binomial coefficient): P(k|q,N) = B(N,k) * q^k * (1-q)^(N-k) ... so the Normalization constant is simply an integral of the posterior above, from 0 to 1: P(k|N) = B(N,k) * integralFromZeroToOne( q^k * (1-q)^(N-k) ) (The Binomial coefficient ( B(N,k) ) can be omitted thoughappears in both the posterior and normalization constant, so it can be omitted.) Now, I've heard that the integral for the normalization constant should be able to be calculated as a series ... something like: k!(N-k)! / (N+1)! Is that correct? (I have some lecture notes from with this series, but can't figure out if it is for the normalization constant integral, or for the posterior distribution of mis-classification (q)) Also, hints are welcome as how to practically calculate this? (factorials are easily creating truncation errors right?) ... AND, how to practically calculate the final plot (the posterior distribution over q, from 0 to 1).

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  • vectorizing loops in Matlab - performance issues

    - by Gacek
    This question is related to these two: http://stackoverflow.com/questions/2867901/introduction-to-vectorizing-in-matlab-any-good-tutorials http://stackoverflow.com/questions/2561617/filter-that-uses-elements-from-two-arrays-at-the-same-time Basing on the tutorials I read, I was trying to vectorize some procedure that takes really a lot of time. I've rewritten this: function B = bfltGray(A,w,sigma_r) dim = size(A); B = zeros(dim); for i = 1:dim(1) for j = 1:dim(2) % Extract local region. iMin = max(i-w,1); iMax = min(i+w,dim(1)); jMin = max(j-w,1); jMax = min(j+w,dim(2)); I = A(iMin:iMax,jMin:jMax); % Compute Gaussian intensity weights. F = exp(-0.5*(abs(I-A(i,j))/sigma_r).^2); B(i,j) = sum(F(:).*I(:))/sum(F(:)); end end into this: function B = rngVect(A, w, sigma) W = 2*w+1; I = padarray(A, [w,w],'symmetric'); I = im2col(I, [W,W]); H = exp(-0.5*(abs(I-repmat(A(:)', size(I,1),1))/sigma).^2); B = reshape(sum(H.*I,1)./sum(H,1), size(A, 1), []); But this version seems to be as slow as the first one, but in addition it uses a lot of memory and sometimes causes memory problems. I suppose I've made something wrong. Probably some logic mistake regarding vectorizing. Well, in fact I'm not surprised - this method creates really big matrices and probably the computations are proportionally longer. I have also tried to write it using nlfilter (similar to the second solution given by Jonas) but it seems to be hard since I use Matlab 6.5 (R13) (there are no sophisticated function handles available). So once again, I'm asking not for ready solution, but for some ideas that would help me to solve this in reasonable time. Maybe you will point me what I did wrong.

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  • Saving "heavy" image to PDF in MATLAB - rendering problem

    - by yuk
    I generate a figure in MATLAB with lot amount of points (100000+) and want to save it into a PDF file. With zbuffer or painters renderer I've got very large and slowly opened file (over 4 Mb) - all points are in vector format. Using OpenGL renderer rasterize the figure in PDF, ok for the plot, but not good for text labels. The file size is about 150 Kb. Try this simplified code, for example: x=linspace(1,10,100000); y=sin(x)+randn(size(x)); plot(x,y,'.') set(gcf,'Renderer','zbuffer') print -dpdf -r300 testpdf_zb set(gcf,'Renderer','painters') print -dpdf -r300 testpdf_pa set(gcf,'Renderer','opengl') print -dpdf -r300 testpdf_op The actual figure is much more complex with several axes and different types of plots. Is there a way to rasterize the figure, but keep text labels as vectors? Another problem with OpenGL is that is does not work in terminal mode (-nosplash -nodesktop) under Mac OSX. Looks like OpenGL is not supported. I have to use terminal mode for automation. The MATLAB version I run is 2007b. Mac OSX server 10.4.

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  • Plot vectors with labels in matlab

    - by mad
    I have a Nx62 matrix with N 62-D vectors and a NX1 vector with the labels for the vectors. I am trying to plot these vectors with their labels because I want to see the behavior of these classes when plotted in a 62-dimensional space. The vectors belong to three classes according to the labels of a NX1 vector cited before. How to to that in matlab? when i do plot(vector,classes) the result is very weird to analyse, how to put labels in the graph? The code i am using to get the labels, vectors and plotting is the following: %labels is a vector with labels, vectors is a matrix where each line is a vector [labels,vectors]=libsvmread('features-im1.txt'); when I plot a three dimensional vector is simple a=[1,2,3] plot(a) and then I get the result but now i have a set of vectors and a set of labels, and i want to see the distribution of them, i want to plot each of these labels but also want to identify their classes. How to do that in matlab? EDIT: This code is almost working. The problem is the fact that for each vector and class the plot will assign a color. I just want three colors and three labels, one per class. [class,vector]=libsvmread('features-im1.txt'); %the plot doesn't allow negative and 0 values in the label class=class+2; labels = {'class -1','class 0','class 1'}; h = plot(vector); legend(h,labels{class})

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  • Introduction to vectorizing in MATLAB - any good tutorials?

    - by Gacek
    I'm looking for any good tutorials on vectorizing (loops) in MATLAB. I have quite simple algorithm, but it uses two for loops. I know that it should be simple to vectorize it and I would like to learn how to do it instead of asking you for the solution. But to let you know what problem I have, so you would be able to suggest best tutorials that are showing how to solve similar problems, here's the outline of my problem: B = zeros(size(A)); % //A is a given matrix. for i=1:size(A,1) for j=1:size(A,2) H = ... %// take some surrounding elements of the element at position (i,j) (i.e. using mask 3x3 elements) B(i,j) = computeSth(H); %// compute something on selected elements and place it in B end end So, I'm NOT asking for the solution. I'm asking for a good tutorials, examples of vectorizing loops in MATLAB. I would like to learn how to do it and do it on my own.

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  • Using Matlab to find maxima for data with a lot of noise

    - by jimbo
    I have noisy data set with three peaks in Matlab and want to do some image processing on it. The peaks are about 5-9 pixels wide at the base, in a 50 x 50 array. How do I locate the peaks? Matlab is very new to me. Here is what I have so far... For my original image, let's call it "array", I tried J = fspecial('gaussian',[5 5], 1.5); C = imfilter(array, J) peaks = imregionalmax(C); but there is still some noise along the baseline between the peaks so I end up getting a ton of local max that are really just noise values. (I tried playing with the size of the filter, but that didn't help.) I also tried peaks = imextendedmax(C,threshold); where the threshold was determined visually... which works but is definitely not a good way to do it since it's not that robust obviously. So, how do I locate these peaks in a robust way? Thanks.

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  • FFT and IFFT on 3D matrix (Matlab)

    - by SteffenDM
    I have a movie with 70 grayscale frames in MATLAB. I have put them in a 3-D matrix, so the dimensions are X, Y and time. I want to determine the frequencies in the time dimension, so I have to calculate the FFT for every point in the 3rd dimension. This is not a problem but I have to return the images to the original form with ifft. In a normal situation this would be true: X = ifft(fft(X)), but this is not the case it seems in MATLAB when you work with multidimensional data. This is the code I use: for i = 1:length y(:, :, i) = [img1{i, level}]; %# take each picture from an cell array and put it end %# and put it in 3D array y2 = ifft(fft(y, NFFT,3), NFFT, 3); %# NFFT = 128, the 3 is the dimension in which i want %# to calculate the FFT and IFFT y is 480x640x70, so there are 70 images of 640x480 pixels. If I use only fft, y2 is 480x640x128 (this is normal because we want 128 points with NFFT). If I use fft and ifft, y2 is 480x640x128 pixels. This is not normal, the 128 should be 70 again. I tried to do it in just one dimension by using 2 for loops and this works fine. The for loops take to much time, though.

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  • Using MATLAB's plotting features as an interactive part of a Fortran program

    - by ldigas
    Although many of you will have a decent idea of what I'm aiming at, just from reading the title -- allow me a simple introduction still. I have a Fortran program - it consists of a program, some internal subroutines, 7 modules with its own procedures, and ... uhmm, that's it. Without going into much detail, for I don't think it's necessary at this point, what would be the easiest way to use MATLAB's plotting features (mainly plot(x,y) with some customizations) as an interactive part of my program ? For now I'm using some of my own custom plotting routines (based on HPGL and Calcomp's routines), but just as part of an exercise on my part, I'd like to see where this could go and how would it work (is it even possible what I'm suggesting?). Also, how much effort would it take on my part ? I know this subject has been rather extensively described in many "tutorials" on the net, but for some reason I have trouble finding the really simple yet illustrative introductory ones. So if anyone can post an example or two, simple ones, I'd be really grateful. Or just take me by the hand and guide me through one working example. platform: IVF 11.something :) on Win XP SP2, Matlab 2008b

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  • skip reading headers in matlab

    - by Paul
    I had a similar question. but what i am trying now is to read files in .txt format into matlab. My problem is with the headers. Manytimes due to errors the system rewrites the headers in the middle of file and then matlab cannot read the file. IS there a way to skip it? I know i can skip reading some characters if i know what the character is. here is the code i am using. [c,pathc]=uigetfile({'*.txt'},'Select the data','V:\data); file=[pathc c]; data= dlmread(file, ',', 1,4); this way i let the user pick the file. My files are huge typically [ 86400 125 ] so naturally it has 125 header fields or more depends on files. Thanks Because the files are so big i cannot copy , but its in format like day time col1 col2 col3 col4 ............................... 2/3/2010 0:10 3.4 4.5 5.6 4.4 ............................... .................................................................. .................................................................. and so on

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  • Which Open Source Licenses can address concerns for an Open Source Game Engine?

    - by Chris
    I am on a team that is looking to open source an engine we are building. It's intended as an engine for Online RPG style games. We're writing it to work on both desktops and android platforms. I've been over to the OSI http://opensource.org/licenses/category to check out the most common licenses. However, this will be my first time going into an open source project and I wanted to know if the community had some insight into which licenses might be best suited. Key licensing concerns: Removing or limiting our liability (most already seem to cover this, but stating for completeness). We want other developers to be able to take part or all of our project and use it in their own projects with proper accreditation to our project. Licensing should not hinder someone's ability to quickly use the engine. They should be able to download a release and start using it without needing to wait on licensing issues. Game content (gfx, sound, etc.) that is not part of the engine should be allowed to be licensed separately. If someone is using our engine, they can retain full copy right of their content, including engine generated data. Our primary goal is exposure, which is why we're going open source to start with. Both for the project and for the individuals developing it. Are there any licenses that can require accreditation visible to players? While I'd put our primary goal as exposure, for licensing the accreditation is less of a concern. From what I've read through (and have been able to understand) it doesn't seem like any of the licenses cover anything that is produced by the licensed software. Are there any that state this specifically, or does simply not mentioning it leave it open for other licensing? Are there any other concerns that we should consider? Has anyone had any issues using any of these licenses?

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  • How to implement physical effect, perspective effect on Android

    - by asedra_le
    I'm researching about 2D game for Android to implement an Android Game Project. My project looks nearly like PaperToss. Instance of throwing a page, my game will throw a coin. Suppose that I have a coin put in three-dimensional that have coordinates at A(x,y,z). I throw that point ahead, after 1/100 second, that coin move from A(x,y,z) to A'(x',y',z'). By this way, I have two problems need to solve. Determine the formulas can be used to compute the coordinates of the coin at time t. This problem is under-researching. I have no idea to solve this problem. Mapping three-dimensional points to a two-dimensional and use those new coordinates (a two-dimensional coordinates) to draw our coin on screen. I have found two solutions for this problem: Orthographic projection & Perspective projection However, my old friend said that OpenGL supports to solve problems like my problems. Any body have experiences about my problems? Help me please :) Thank for reading my question.

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  • Farseer Physics: Ways to create a Body?

    - by EdgarT
    I want to create something similar to this using farsser and Kinect: https://vimeo.com/33500649 This is my implementation until now: http://www.youtube.com/watch?v=GlIvJRhco4U I have the outline vertices and the triangulation of the user. And following the Texture to Polygonmsample i used this line to create the shape, where farseerObject is a list of vertices of the triangles: _compound = BodyFactory.CreateCompoundPolygon(World, farseerObject, 1f, BodyType.Dynamic); But I have to update the body each frame (like 30 fps) and this is very slow. I get just 2 or 3 fps. There's another (faster) way to create the Body from a list of triangles or the contour vertices?

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  • Matlab Simulink version control with multiple developers

    - by Jon Mills
    We're using Matlab Simulink for model development (and Real-Time Workshop autocoding) within a team of several developers. We currently use Visual Source Safe (yes, I know its terrible) for version control, using locks to prevent conflicting changes. We'd like to migrate our programme to a different version control system (svn, hg or git), but we're concerned about performing merges and diffs on Simulink .mdl files. Does anybody have useful experience in performing merges on Simulink files?

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  • Running multiprocess applications from MATLAB

    - by Jacob
    I've written a multitprocess application in VC++ and tried to execute it with command line arguments with the system command. It runs, but only on one core --- any suggestions? Update:In fact, it doesn't even see the second core. I used OpenMP and used omp_get_max_threads() and omp_get_thread_num() to check and omp_get_max_threads() seems to be 1 when I execute the application from MATLAB but it's 2 (as is expected) if I run it from the command window.

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  • MATLAB Mex files

    - by hkf
    Is there a way to get the mex file for a built-in MATLAB m- file? If yes, how? If no, does that mean I have to write the C code myself (oh nooo!!!)

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  • MATLAB date selection popup calendar for gui

    - by Doresoom
    Does anyone know of a method to display a popup date selection calendar in a MATLAB gui? I know the financial toolbox has a uicalendar function, but unfortunately I don't have that toolbox. I have a hunch I'm going to have to use some Java or some other language for this one, which I know nothing about. I'm looking for something similar to this: which would return a date string after the user selects the date.

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  • matlab's phi symbol

    - by ldigas
    Not that significant, but annoying to no end. Why does matlab has no small phi (\varphi) symbol ? It has pretty much all other symbols LaTeX offers, but not this one. Why ? I may be wrong of course, in which case would be delighted if someone could prove me wrong...

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  • problem with sortrows MATLAB

    - by Jessy
    Hi, My question is related with the previous solved question in http://stackoverflow.com/questions/2925623/how-to-save-data-in-txt-file-in-matlab my problem is that, I decided to unsorted the output, however this error comes out when I removed the sortrows. And no error when I leave the sortrows I'm curious why.

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  • Matlab: Print text in input field

    - by Adam Doyle
    Using Matlab, I have this code: value = input('>> Enter a value: '); and basically, I want a "default" value to the right of the colon (sortof like this) >> Enter a value: 12 where "12" is editable such that the user could [backspace] [backspace] and change the value to, say, "20" or something. Is there any (easy) way to do this? Thanks!

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  • matlab write image into eps file

    - by Tim
    In MATLAB, how do you write a matrix into an image of eps format? It seems imwrite does not support eps? convert is not working on the Linux server I am using $ convert exploss_stumps.jpg exploss_stumps.eps convert: missing an image filename `exploss_stumps.eps' @ convert.c/ConvertImageCommand/2838 Any idea why?

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  • Grayscale in matlab

    - by ruthenium
    I'm trying to convert a 2D array to grayscale but using mat2gray doesn't do anything and imshow() appears to create a binary image that when I graph I cannot rotate it, e.g. the original array is 2d but maps in 3d. So, what is the best way to take a grayscale of 2d array in Matlab so if you have A=rand(5,10) or something and want to take a grayscale of that, what is the best way?

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  • Best way to organize MATLAB classes?

    - by jjkparker
    MATLAB has two ways of organizing classes: @-directories: @ClassName\ ClassName.m Method1.m Method2.m Single files: ClassName.m: classdef ClassName methods % all methods included here end end The first style existed before the new classdef syntax, but seems to be a more structured way of doing things. The second style (everything in a single file) is new. Which method do you use, and why?

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