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  • Is it possible to see the underlying implementation of built in functions of matlab?

    - by user198729
    I'm using this example code to grayscale an image,but the result is not right: I = imread('coins.png'); level = graythresh(I); BW = im2bw(I,level); imshow(BW) Where to see how graythresh is actually implemented? BTW,is there a reason for using matlab feels so alike with python? Or is it known that graythresh doesn't work well for images with little spatial resolution(like 62*21 ones)?

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  • Where is my software installed in Linux?

    - by David
    I use whereis matlab and find: /usr/local/bin/matlab , which is a very long bash file. How can I find where matlab is installed, I mean, its installed folder. EDIT: I used the following method: open matlab and use edit svds.m to open the svds.m file and the editor shows the folder:)

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  • What's this setting of MATLAB for(which is causing lots of troubles for lots of people)?

    - by Runner
    This setting in PATH: D:\MATLAB\R2007b\bin\win32 Here is a fresh bad affect by this setting for me: http://stackoverflow.com/questions/2712913/why-does-this-program-require-msvcr80-dll-and-whats-the-best-solution-for-this-k And here's an issue reported by another guy: http://groups.google.com/group/ggobi/browse_thread/thread/dacea0fa93dcaf75 What's that setting for and why it's causing so many problems?

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  • How do i get rid of NaNs in matlab?

    - by Paul
    I have files which have many empty cells which appear as NaNs when i use cell2mat but the problem is when i need to get the average values i cannot work with this as it shows error with NaN. In excel it overlooks, how do i do the same in matlab? thanks

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  • How to add types from external assembly to toolbox control? (WPF)

    - by Louis Rhys
    I am trying to do something like this in my WPF application: ToolboxControl ctrl = new ToolboxControl(); Assembly assembly = Assembly.LoadFile(file); var category = new ToolboxCategory(assembly.GetName().Name); foreach (Type t in assembly.GetTypes()) { var wrapper = new ToolboxItemWrapper(t, t.Name); category.Add(wrapper); } ctrl.Categories.Add(category); i.e. adding ToolboxItemWrappers for each type found in an assembly. However the last line throws the following exception (see image) All dependencies of the external assembly are also referenced in the main (WPF) application. So what's wrong here and how to fix it?

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  • How can I read a textfile into matlab and make it a list?

    - by Ben Fossen
    I have a textfile that has the format gene complement(22995..24539) /gene="ppp" /locus_tag="MRA_0020" CDS complement(22995..24539) /gene="ppp" /locus_tag="MRA_0020" /codon_start=1 /transl_table=11 /product="putative serine/threonine phosphatase Ppp" /protein_id="ABQ71738.1" /db_xref="GI:148503929" gene complement(24628..25095) /locus_tag="MRA_0021" CDS complement(24628..25095) /locus_tag="MRA_0021" /codon_start=1 /transl_table=11 /product="hypothetical protein" /protein_id="ABQ71739.1" /db_xref="GI:148503930" gene complement(25219..26802) /locus_tag="MRA_0022" CDS complement(25219..26802) /locus_tag="MRA_0022" /codon_start=1 /transl_table=11 /product="hypothetical protein" /protein_id="ABQ71740.1" /db_xref="GI:148503931" I would like to read the textfile into Matlab and make a list with the information from the line gene as the starting point for each item in the list. So for this example there will be 3 items in the list. I have tried a few things and cannot get this to work. Anyone have any ideas of what I can do?

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  • Matlab: how do I force ode45 to take steps of exactly 0.01 on the T axis?

    - by Gravitas
    I'm using Matlab to solve a differential equation. I want to force ode45 to take constant steps, so it always increments 0.01 on the T axis while solving the equation. How do I do this? ode45 is consistently taking optimized, random steps, and I can't seem to work out how to make it take consistent, small steps of 0.01. Here is the code: options= odeset('Reltol',0.001,'Stats','on'); %figure(1); %clf; init=[xo yo zo]'; tspan=[to tf]; %tspan = t0:0.01:tf; [T,Y]=ode45(name,tspan,init,options);

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  • How do I get real integer overflows in MATLAB/Octave?

    - by marvin2k
    I'm working on a verification-tool for some VHDL-Code in MATLAB/Octave. Therefore I need data types which generate "real" overflows: intmax('int32') + 1 ans = -2147483648 Later on, it would be helpful if I can define the bit width of a variable, but that is not so important right now. When I build a C-like example, where a variable gets increased until it's smaller than zero, it spins forever and ever: test = int32(2^30); while (test > 0) test = test + int32(1); end Another approach I tried was a custom "overflow"-routine which was called every time after a number is changed. This approach was painfully slow, not practicable and not working in all cases at all. Any suggestions?

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  • Sharing a mex64 file across computers

    - by Shaihi
    I have a mex64 dll compiled on my machine. I used Matlab 2009b with VS2008 Pro to compile the dll. The dll works fine on my Matlab installation. I want a colleague to use the dll so I sent it to him and he gets the following error message when trying to use the dll: ??? Invalid MEX-file 'filename.mexw64': The specified module could not be found. My current assumption is that this is caused because he uses an older Matlab version or missing a dll that I have. I ran dependency checker and asked him to check that he has all the listed dlls. I am still waiting for him to confirm his Matlab version. What other reasons can cause this and can the Matlab version make a difference? (I mean R2009a when I have R2009B and not a huge version diff)

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  • Matlab code help. Backward Euler method.

    - by m0s
    Here is the matlab/freemat code I got to solve ODE numerically using backward Euler method. However the results are inconsistent with my textbook results, and sometimes even ridiculously inconsistent. Please point out what is wrong with the code. I have already asked this question on mathoverflow.com no help there, hope someone here can help. function [x,y]=backEuler(f,xinit,yinit,xfinal,h) %f - this is your y prime %xinit - initial X %yinit - initial Y %xfinal - final X %h - step size n=(xfinal-xinit)/h; %Calculate steps %Inititialize arrays... %1st elements take xinit and yinit corespondigly, the rest fill with 0s x=[xinit zeros(1,n)]; y=[yinit zeros(1,n)]; %Numeric routine for i=1:n x(i+1)=x(i)+h; ynew=y(i)+h*(f(x(i),y(i))); y(i+1)=y(i)+h*f(x(i+1),ynew); end end

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  • MATLAB: How do I get 3D coordiantes from a user-click?

    - by John
    I'm using Matlab to create a small chess game for one of my courses this semester. The thing I'm having trouble with is having the user be able to select one of the chess pieces. To simplify things, I'm making it so that the user selects a piece by clicking on the square that the chess piece resides on rather than clicking the piece itself (which I assume would be much more difficult). I know how to get the x and y coordinates of the view-port, but how do I transform these coordinates into 3-space coordinates? I know that there are multiple x,y,z coordinates associated with each view-port coordinate, but I'm only interested in the x,y,z coordinate where z = 0 (since the board itself is in the x,y plane that intersects the z axis where z = 0). Thanks!

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  • How to make a random number generator in matlab that is based on percentages?

    - by Ben Fossen
    I am currently using the built in random number generator. for example nAsp = randi([512, 768],[1,1]); 512 is the lower bound and 768 is the upper bound, the random number generator chooses a number from between these two values. What I want is to have two ranges for nAsp but I want one of them to get called 25% of the time and the other 75% of the time. Then gets plugged into he equation. Does anyone have any ideas how to do this or if there is a built in function in matlab already? for example nAsp = randi([512, 768],[1,1]); gets called 25% of the time nAsp = randi([690, 720],[1,1]); gets called 75% of the time

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  • MATLAB: How do I get 3D coordiantes from a user-click?

    - by Tim
    I'm using Matlab to create a small chess game for one of my courses this semester. The thing I'm having trouble with is having the user be able to select one of the chess pieces. To simplify things, I'm making it so that the user selects a piece by clicking on the square that the chess piece resides on rather than clicking the piece itself (which I assume would be much more difficult). I know how to get the x and y coordinates of the view-port, but how do I transform these coordinates into 3-space coordinates? I know that there are multiple x,y,z coordinates associated with each view-port coordinate, but I'm only interested in the x,y,z coordinate where z = 0 (since the board itself is in the x,y plane that intersects the z axis where z = 0). Thanks!

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  • Why i get this following error when using dir in Matlab?

    - by nata
    Matlab keep give me following error message : ??? Error using == dir Argument must contain a string. Error in == Awal at 15 x = dir(subDirs) Below is my codes : %MY PROGRAM clear all; clc; close all; %-----Create Database----- TrainDB = uigetdir('','Select Database Directory'); TrainFiles = dir(TrainDB); dirIndex = [TrainFiles.isdir]; [s subDirNumber] = size(dirIndex); for i = 3:subDirNumber subDirs = {TrainFiles(i).name}; subDirs = strcat(TrainDB,'\',subDirs); x = dir(subDirs) %<-------Error Here end Is something wrong with the codes? Your help will be appreciated. I'm sorry for my bad English.

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  • How do I create efficient instance variable mutators in Matlab?

    - by Trent B
    Previously, I implemented mutators as follows, however it ran spectacularly slowly on a recursive OO algorithm I'm working on, and I suspected it may have been because I was duplicating objects on every function call... is this correct? %% Example Only obj2 = tripleAllPoints(obj1) obj.pts = obj.pts * 3; obj2 = obj1 end I then tried implementing mutators without using the output object... however, it appears that in MATLAB i can't do this - the changes won't "stick" because of a scope issue? %% Example Only tripleAllPoints(obj1) obj1.pts = obj1.pts * 3; end For application purposes, an extremely simplified version of my code (which uses OO and recursion) is below. classdef myslice properties pts % array of pts nROW % number of rows nDIM % number of dimensions subs % sub-slices end % end properties methods function calcSubs(obj) obj.subs = cell(1,obj.nROW); for i=1:obj.nROW obj.subs{i} = myslice; obj.subs{i}.pts = obj.pts(1:i,2:end); end end function vol = calcVol(obj) if obj.nROW == 1 obj.volume = prod(obj.pts); else obj.volume = 0; calcSubs(obj); for i=1:obj.nROW obj.volume = obj.volume + calcVol(obj.subs{i}); end end end end % end methods end % end classdef

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  • Is there any function in Matlab for changing the form of matrix?

    - by niko
    Hi, I have to get the unknown matrix by changing the form of known matrix considering the following rules: H = [-P'|I] G = [I|P] where H is known matrix G is unknown matrix which has to be calculated I is identity matrix So for example if we had a matrix H = [1 1 1 1 0 0; 0 0 1 1 0 1; 1 0 0 1 1 0] its form has to be changed to H = [1 1 1 1 0 0; 0 1 1 0 1 0; 1 1 0 0 0 1] so -P' = [1 1 1; 0 1 0; 1 1 0] and in case of binary matrices -P = P therefore G = [1 0 0 1 1 1; 0 1 0 0 1 0; 0 0 1 1 1 0] I know how to solve it on the paper by performing basic row operations but don't know how if there is any function already written in Matlab to calculate G from H or H from G by considering the above rules. I would be very thankful if anyone of you could suggest any method for solving the given problem. Thank you.

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  • Update on: How to model random non-overlapping spheres of non-uniform size in a cube using Matlab?

    - by user3838079
    I am trying to use MATLAB for generating random locations for non-uniform size spheres (non-overlapping) in a cube. The for loop in the code below never seems to end. I don't know what am missing in the code. I have ran the code for no. of spheres (n) = 10; dims = [ 10 10 10 ] function [ c r ] = randomSphere( dims ) % creating one sphere at random inside [0..dims(1)]x[0..dims(2)]x... % radius and center coordinates are sampled from a uniform distribution % over the relevant domain. % output: c - center of sphere (vector cx, cy,... ) % r - radius of sphere (scalar) r = rand(1); % you might want to scale this w.r.t dims or other consideration c = r + rand( size(dims) )./( dims - 2*r ); % make sure sphere does not exceed boundaries function ovlp = nonOverlapping( centers, rads ) % check if several spheres with centers and rads overlap or not ovlp = false; if numel( rads ) == 1 return; % nothing to check for a single sphere end dst = sqrt( sum( bsxfun( @minus, permute( centers, [1 3 2] ),... permute( centers, [3 1 2] ) ).^2, 3) ); ovlp = dst >= bsxfun( @plus, rads, rads.' ); %' all distances must be smaller than r1+r2 ovlp = any( ovlp(:) ); % all must not overlap function [centers rads] = sampleSpheres( dims, n ) % dims is assumed to be a row vector of size 1-by-ndim % preallocate ndim = numel(dims); centers = zeros( n, ndim ); rads = zeros( n, 1 ); ii = 1; while ii <= n [centers(ii,:), rads(ii) ] = randomSphere( dims ); if nonOverlapping( centers(1:ii,:), rads(1:ii) ) ii = ii + 1; % accept and move on end end

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  • Better code for accessing fields in a matlab structure array?

    - by John
    I have a matlab structure array Modles1 of size (1x180) that has fields a, b, c, ..., z. I want to understand how many distinct values there are in each of the fields. i.e. max(grp2idx([foo(:).a])) The above works if the field a is a double. {foo(:).a} needs to be used in the case where the field a is a string/char. Here's my current code for doing this. I hate having to use the eval, and what is essentially a switch statement. Is there a better way? names = fieldnames(Models1); for ix = 1 : numel(names) className = eval(['class(Models1(1).',names{ix},')']); if strcmp('double', className) || strcmp('logical',className) eval([' values = [Models1(:).',names{ix},'];']); elseif strcmp('char', className) eval([' values = {Models1(:).',names{ix},'};']); else disp(['Unrecognized class: ', className]); end % this line requires the statistics toolbox. [g, gn, gl] = grp2idx(values); fprintf('%30s : %4d\n',names{ix},max(g)); end

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  • MATLAB: What is an appropriate Data Structure for a Matrix with Random Variable Entries?

    - by user568249
    I'm currently working in an area that is related to simulation and trying to design a data structure that can include random variables within matrices. To motivate this let me say I have the following matrix: [a b; c d] I want to find a data structure that will allow for a, b, c, d to either be real numbers or random variables. As an example, let's say that a = 1, b = -1, c = 2 but let d be a normally distributed random variable with mean 0 and SD 1. The data structure that I have in mind will give no value to d. However, I also want to be able to design a function that can take in the structure, simulate an uniform(0,1), obtain a value for d using an inverse CDF and then spit out an actual matrix. I have several ideas to do this (all related to the MATLAB icdf function) but would like to know how more experienced programmers would do this. In this application, it's important that the structure is as "lean" as possible since I will be working with very very large matrices and memory will be an issue.

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  • LaTeX-like display programming environment

    - by Gage
    I used to be a hobbyist programmer, but now I'm also a fairly experienced physicist and find myself programming to solve certain problems quite a lot. In physics, we use variables with superscripts, subscripts, italics, underlines, etc etc. To bridge this gap to the computer we usually use LaTeX. Now, I generally use MATLAB for handling any data and such, and find it very irritating that I can't basically use LaTeX for variable names. Something as simple as sy has to be named either sigma_y or some descriptive name like peak_height_error. I don't necessarily want full on workable LaTeX in my code, but I do want to be able to use greek letters and super/sub-scripts at the very least. Does this exist?

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