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  • what is problem in the following matlab codes

    - by raju
    img=imread('img27.jpg'); %function rectangle=rect_test(img) % edge detection [gx,gy]=gradient(img); gx=abs(gx); gy=abs(gy); g=gx+gy; g=abs(g); % make it 300x300 img=zeros(300); s=size(g); img(1:s(1),1:s(2))=g; figure; imagesc((img)); colormap(gray); title('Edge detection') % take the dct of the image IM=abs(dct2(img)); figure; imagesc((IM)); colormap(gray); title('DCT') % normalize m=max(max(IM)); IM2=IM./m*100; % get rid of the peak size_IM2=size(IM2); IM2(1:round(.05*size_IM2(1)),1:round(.05*size_IM2(2))) = 0; % threshold L=length( find(IM2>20)) ; if( L > 60 ) ret = 1; else ret = 0; end

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  • plot 3D and combine in matlab

    - by George
    Hello ,i have this matrix "experiment=2*rand(npoints,3)-1". I want to plot in in 3D,so i use "mesh(experiment)". How can i take red points in my plot? Also,i want to implement in the above plot , a sphere with radius 1 at 0,0,0. I did : mesh(experiment) hold on [x,y,z]=sphere; r=1; mesh(r*x,r*y,r*z) hold off but 1) i am not taking radius 1 2) the figures just showing in the same graph but don't combine Thanks

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  • How do I do multiple assignment in MATLAB?

    - by Benjamin Oakes
    Here's an example of what I'm looking for: >> foo = [88, 12]; >> [x, y] = foo; I'd expect something like this afterwards: >> x x = 88 >> y y = 12 But instead I get errors like: ??? Too many output arguments. I thought deal() might do it, but it seems to only work on cells. >> [x, y] = deal(foo{:}); ??? Cell contents reference from a non-cell array object. How do I solve my problem? Must I constantly index by 1 and 2 if I want to deal with them separately?

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  • MATLAB: comparing all elements in three arrays

    - by sasha
    I have three 1-d arrays where elements are some values and I want to compare every element in one array to all elements in other two. For example: a=[2,4,6,8,12] b=[1,3,5,9,10] c=[3,5,8,11,15] I want to know if there are same values in different arrays (in this case there are 3,5,8)

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  • Problem with averaging corrupted images to eliminate the noise in MATLAB

    - by Mertie Pertie
    I want to average some .jpg images which are corrupted by zero-mean Gaussian additive noise. After searching around, I figured out to add the image matrices and divide the sum by the number of matrices. However, the resultant image is totally black. Normally when the number of image increases then the resultant image gets better. But when I use more images it gets darker. I am using 800x600 black and white .jpg images. Here is the script I used: image1 = imread ('PIC1.jpg'); image2 = imread ('PIC2.jpg'); image3 = imread ('PIC3.jpg'); image4 = imread ('PIC4.jpg'); sum = image1 + image2 + image3 + image4; av = sum / 4; imshow(av);

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  • MATLAB submatrix over variable dimensions

    - by rlbond
    I have a variable dimension matrix, X. I want a function that will get the first half of X in one dimension. I.E., I want something like this: function x = variableSubmatrix(x, d) if d == 1 switch ndims(x) case 1 x = x(1:end/2); case 2 x = x(1:end/2, :); case 3 x = x(1:end/2, :, :); (...) end elseif d == 2 switch ndims(x) case 2 x = x(:, 1:end/2); case 3 x = x(:, 1:end/2, :); (...) end elseif (...) end end I'm not quite sure how to do this. I need it to be fast, as this will be used many times in computation.

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  • matlab image processing 3d

    - by jaysean
    i have 100 b&w image of smthing.the probllem is i want to scan each image in 0&1 formatin mby n format and then place each image to one over one and again scan and save them in mbynby100 form. how i do this and from where i should start _jaysean

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  • Gaps In Plot Of Piecewise Function in Matlab

    - by eng_sub
    Hello, I want to plot a piecewise function, but I don't want any gaps to appear at the junctures, for example: t=[1:8784]; b=(26.045792 + 13.075558*sin(0.0008531214*t - 2.7773943)).*((heaviside(t-2184))-(heaviside(t-7440))); plot(b,'r','LineWidth', 1.5);grid on there should not be any gaps appearing in the plot between the three intervals , but they do. I want the graph to be continueous without gaps. Any suggestions on how to achieve that. Thanks in advance.

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  • Matlab matrix translation and rotation multiple times

    - by pinnacler
    I have a map of individual trees from a forest stored as x,y points in a matrix. I call it fixedPositions. It's cartesian and (0,0) is the origin. I would like 0/360 degrees to be the top of the screen and 90 degrees to be to the right. Given a velocity and a heading, i.e. .5 m/s and 60 degrees (2 o'clock equivalent on a watch), how do I rotate that x,y points, so that the new origin is centered at (.5cos(60),.5sin(60)) and 60 degrees is now at the top of the screen? Then if I were to give you another heading and speed, i.e. 0 degrees and 2m/s, it should calculate it from the last point, not the original fixedPositions origin. I've wasted my day trying to figure this out. I wish I took matrix algebra but I'm at a loss. I tried doing cos(30) and even those wouldn't compute correctly, which after an hour I realize were in radians.

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  • Problem using the find function in MATLAB

    - by Peter Etchells
    I have two arrays of data that I'm trying to amalgamate. One contains actual latencies from an experiment in the first column (e.g. 0.345, 0.455... never more than 3 decimal places), along with other data from that experiment. The other contains what is effectively a 'look up' list of latencies ranging from 0.001 to 0.500 in 0.001 increments, along with other pieces of data. Both data sets are X-by-Y doubles. What I'm trying to do is something like... for i = 1:length(actual_latency) row = find(predicted_data(:,1) == actual_latency(i)) full_set(i,1:4) = [actual_latency(i) other_info(i) predicted_info(row,2) ... predicted_info(row,3)]; end ...in order to find the relevant row in predicted_data where the look up latency corresponds to the actual latency. I then use this to created an amalgamated data set, full_set. I figured this would be really simple, but the find function keeps failing by throwing up an empty matrix when looking for an actual latency that I know is in predicted_data(:,1) (as I've double-checked during debugging). Moreover, if I replace find with a for loop to do the same job, I get a similar error. It doesn't appear to be systematic - using different participant data sets throws it up in different places. Furthermore, during debugging mode, if I use find to try and find a hard-coded value of actual_latency, it doesn't always work. Sometimes yes, sometimes no. I'm really scratching my head over this, so if anyone has any ideas about what might be going on, I'd be really grateful.

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  • Averaging corrupted images to eliminate the noise in Matlab

    - by Mertie Pertie
    Hi all As you can get it from the title, I want to average some .jpg images which are corrupted by zero-mean Gaussian additive. After searching over internet, I figured out to add image matrices and divide the sum by the # of matrices. However the resultant image is totally black. Normally when the number of image increases then the resultant image gets better. But When I use more images it gets darker. I am using 800x600 black and white images with .jpg ext Here is the script I used; image1 = imread ('PIC1.jpg'); image2 = imread ('PIC2.jpg'); image3 = imread ('PIC3.jpg'); image4 = imread ('PIC4.jpg'); sum = image1 + image2 + image3 + image4; av = sum / 4; imshow(av); Thanks in advance

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  • how to animate 2 surfaces in Matlab?

    - by Kate
    Hi everyone, I've written this code which makes an animation of 2 ellipsoids. Parameter k1 of these ellipsoids must depend on time (so they'd move asynchronously), but I need to animate them in one figure. Can I use loop for it or is it better to use timer & some kind of callback functions? The second problem - I need to move inner ellipsoid so they would have one common side. How can I do this? a=5; b=a; c=10; u = (0:0.05*pi:2*pi)'; v = [0:0.05*pi:2*pi]; X = a*sin(u)*cos(v); Y = a*sin(u)*sin(v); Z = c*cos(u)*ones(size(v)); Z(Z0)=0; % cut upper V1=4/3*pi*a*b*c; d=1/2; e=2^d; a2=a/e; b2=a/e; c2=c; V2=4/3*pi*a2*b2*c2; X2 = a2*sin(u)*cos(v);%-2.5; Y2 = b2*sin(u)*sin(v); Z2 = c2*cos(u)*ones(size(v));%+0.25; Z2(Z20)=0; % cut h=1/3; for j = 1:20 k1=(sin(pi*j/20)+0.5)^h; a=a*k1; c=c*k1; X = a*sin(u)*cos(v); Y = a*sin(u)*sin(v); Z = c*cos(u)*ones(size(v)); Z(Z0)=0; a2=a2*k1; b2=a2*k1; c2=c2*k1; X2 = a2*sin(u)*cos(v)+5;%-2.5; Y2 = b2*sin(u)*sin(v); Z2 = c2*cos(u)*ones(size(v));%+0.25; Z2(Z20)=0; hS1=surf(X,Y,Z); alpha(.11) hold on hS2=surf(X2,Y2,Z2); hold off axis([-20 20 -20 20 -20 20]); F(j) = getframe; end movie(F,4)

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  • Edit axes to an image in matlab ?

    - by ZaZu
    Hello, I would like to edit the axes in my series of images being displayed .. This is how my image looks like : As you can see, it starts from 0 to ~~500 from top to bottom, can I invert that ? Plus I want to mirror the image being shown, so that it starts from left to right ... Or if its possible, let the axes show from right to left ? Thanks !

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  • Finding many local max in an image (using MatLab)

    - by wenh42
    How do you go about figuring our multiple max in a 2D image where the max aren't necessarily all the same height? I have found that the imregionalmax(), imextendedmax(), and findpeaks() functions aren't necessarily that helpful because they give many local max that are really just maxes within the background noise. I tried bw=arrayimdilate(array,[1 1 1; 1 0 1; 1 1 1]) but that also is kind of limited for the same reasons (same thing with expanding the matrix that it uses). I'd definitely appreciate some help..

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  • Replace some column values depending on a condition, MATLAB

    - by darkcminor
    I have a matrix like A= 4.0000 120.0000 92.0000 0 0 37.6000 0.1910 30.0000 10.0000 168.0000 74.0000 0 0 38.0000 0.5370 34.0000 10.0000 139.0000 80.0000 0 0 27.1000 1.4410 57.0000 1.0000 139.0000 60.0000 23.0000 846.0000 30.1000 0.3980 59.0000 5.0000 136.0000 72.0000 19.0000 175.0000 25.8000 0.5870 51.0000 7.0000 121.0000 0 0 0 30.0000 0.4840 32.0000 I want to replace the values of the first column that are greater than '5' to 0, also in the second column if the values are in range 121-130 replace them by 0, if they are in range 131-140 replece by 1, 141-150 by 2, 151-160 by 3... so the result matrix would be A= 4.0000 0.0000 92.0000 0 0 37.6000 0.1910 30.0000 0.0000 4.0000 74.0000 0 0 38.0000 0.5370 34.0000 0.0000 1.0000 80.0000 0 0 27.1000 1.4410 57.0000 1.0000 1.0000 60.0000 23.0000 846.0000 30.1000 0.3980 59.0000 5.0000 1.0000 72.0000 19.0000 175.0000 25.8000 0.5870 51.0000 0.0000 0.0000 0 0 0 30.0000 0.4840 32.0000 How to acomplish this? I was trying something like counter=1; for i = 1: rows if A(i,1) > 5 A(i ,1) = 0; end if A(i,2) > 120 && A(i,2) < 130 A(i ,2) = 0; end counter = counter+1; end Using a case could do the trick?

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  • Drawing and filling different polygons at the same time in MATLAB

    - by Hossein
    Hi,I have the code below. It load a CSV file into memory. This file contains the coordinates for different polygons.Each row of this file has X,Y coordinates and a string which tells that to which polygon this datapoint belongs. for example a polygone named "Poly1" with 100 data points has 100 rows in this file like : Poly1,X1,Y1 Poly1,X2,Y2 ... Poly1,X100,Y100 Poly2,X1,Y1 ..... The index.csv file has the number of datapoint(number of rows) for each polygon in file Polygons.csv. These details are not important. The thing is: I can successfully extract the datapoints for each polygon using the code below. However, When I plot the lines of different polygons are connected to each other and the plot looks crappy. I need the polygons to be separated(they are connected and overlapping the some areas though). I thought by using "fill" I can actually see them better. But "fill" just filles every polygon that it can find and that is not desirable. I only want to fill inside the polygons. Can someone help me? I can also send you my datapoint if necessary, they are less than 200Kb. Thanks [coordinates,routeNames,polygonData] = xlsread('Polygons.csv'); index = dlmread('Index.csv'); firstPointer = 0 lastPointer = index(1) for Counter=2:size(index) firstPointer = firstPointer + index(Counter) + 1 hold on plot(coordinates(firstPointer:lastPointer,2),coordinates(firstPointer:lastPointer,1),'r-') lastPointer = lastPointer + index(Counter) end

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  • how to use summation in matlab???

    - by lucky
    i have a randomly generated vector say A of length M say A=rand(M,1) and also i have function X(k)=sin(2*pi*k) how would i find Y(k) which is summation of A(l)*X(k-l) as l goes from 0 to M ... assume any value of k... but answer should be summation of all M+1 terms

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  • Decision region plot for neural network in matlab

    - by Taban
    I have a neural network trained with backpropagation algorithm. I also create data set (input and target) random. Now I want to plot a decision region where each region is marked with a red star or with a blue circle according to whether it belongs to class 1 or -1. I searched a lot but just find plotpc function that is for perceptron algorithm. What should I try now? Any link or answer really helps. Thanks

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  • Classify data (cell array) based on years in MATLAB

    - by user2991243
    Suppose that we have this cell array of data : a={43 432 2006; 254 12 2008; 65 35 2000; 64 34 2000; 23 23 2006; 64 2 2010; 32 5 2006; 22 2 2010} Last column of this cell array is years. I want classify data(rows) based on years like this : a_2006 = {43 432 2006; 32 5 2006; 32 5 2006} a_2008 = {254 12 2008}; a_2000 = {65 35 2000; 64 34 2000} a_2010 = {64 2 2010; 22 2 2010} I have different years in column three in every cell array (this cell array is a sample) so I want an automatic method to determine the years and classify them to a_yearA , a_yearB etc. or other naming that I can distinguish years and call data years easily. How can I do this? Thanks.da

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  • MATLAB: Automatic detection of relations between workspace variables through functions

    - by Peterstone
    Hi all, I´m trying to write a function what detect this relation between the variables I have got in the workspace: v1 - fft(v2) = 0 Where v1, v2 are variables of my workspace. Sometimes I need to know which variables have a certain numerical relation. If I have thirty, I don´t want to be looking for this relation in "manual way", just itroducing a sentence for each pair of different variables. I would like a function in which I introuce (or I modify this function every time I need it) the sentence (for instance what I wrote before) and the function show me the pair of variables a I am looking for. Does anyone know how to do it? Thank you so much!

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