Michael

Actif depuis 2012

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"text" handle, how do I grab all text and rotate it in a figure?
Hi, I've created a figure and annotated it using "text(x,y,'sample)" code, and I've got about 8 instances of it on my figure....

plus de 12 ans il y a | 1 réponse | 3

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Fastest way to compute spectral norm of a matrix?
Hello I can't find any mention of the spectral norm in the documentation. I want to calculate max(|Ax|)/x for any vector x...

plus de 12 ans il y a | 1 réponse | 0

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Question

colorbar scientific notation exponent won't go away
Hi I've got a square matrix and I'm using imshow and colorbar to plot it. The values are small, so colorbar naturally uses x1...

plus de 12 ans il y a | 1 réponse | 1

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i've an gray scale image I to be decomposed...i want to extract the low frequency and high frequency component out of it...can anybody help me?
I don't know what LL1 or HH1 are but the 2D discrete Fourier transform should find you the frequency components of the image, in...

plus de 12 ans il y a | 0

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How to plot 3D contours of temperature, on the 3D surface of the body !?
My own suggestion might be to generate the 3D surface using g = surf(x), remove the edges using set(g,'EdgeColor','none'), and t...

plus de 12 ans il y a | 1

Question

MATLAB automatically chose colours for my plot, how do I get them?
ydata is 70x5 xdata is 70x1 plot(xdata, ydata) generates five lines with different colours how do I find what these colou...

plus de 12 ans il y a | 1 réponse | 0

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Question

best way to plot error bars for multiple data?
Hi I have five pairs of curves to plot on a 2d graph. This, I can just about manage- I use five colours and then distinguish ...

plus de 12 ans il y a | 1 réponse | 0

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Question

how to assign a variable using a string
I have a set of variables called "error1", "error2", etc. Each is a 4D matrix and I want to extract certain parts of them for...

plus de 12 ans il y a | 2 réponses | 0

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Question

use of cell arrays to store matrices... but parfor gives an error
Hi, I've got a loop which creates three matrices, and I want to store these for each iteration. Previously I've been saving t...

presque 13 ans il y a | 1 réponse | 2

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Question

what is the mathematical notation equivalent to abs(A) for matrix A?
I'm trying to write notes for my code and I want to know if there's a common notation which means what abs(A) does, ie. multiply...

presque 13 ans il y a | 2 réponses | 0

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Question

preallocating sparse 4d matrix
Hi I've got some code that preallocates some matrix L = zeros(50,50,50,50); and then iterates along the first two dimensions ...

presque 13 ans il y a | 2 réponses | 0

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Question

why does parfor execute loops in a random order?
I can't see any reason why, and if my PC crashes during a 20,000 loop iteration, it's a pain to figure out which iterations are ...

presque 13 ans il y a | 1 réponse | 0

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Question

"print" saves image with tiny title/xlabel
Hi I'm trying to save a figure using 'print' but this process doesn't preserve the image/text proportions that are on my scre...

presque 13 ans il y a | 2 réponses | 0

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Question

imresize is blurring my image!
Hello I have a 128x128 matrix and I want to scale it down to 32x32. MATLAB's algorithm "imresize" seems to involve a smoothin...

presque 13 ans il y a | 1 réponse | 0

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Question

setting processor affinity for individual parallel toolbox workers
Hi Just wondering does anyone know if there are any general rules for improving speed by setting processor affinity using the...

presque 13 ans il y a | 1 réponse | 0

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Question

Matlab loop (with load/save) is getting slower and slower
Hi I'm running a large code that is basically: for i = 1:50 load(i.mat, input); output = myfun(input); ...

presque 13 ans il y a | 3 réponses | 0

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Question

Want to change the range of a single axis of a plotyy figure
Hi I want my x-axis to be tight to the data on a plotyy graph. I can't seem to do it without messing up the axes. My data ...

environ 13 ans il y a | 2 réponses | 0

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Question

Does logical indexing have a direct inverse?
Say I have some region-of-interest filter X, and I use B = A(X~=0) to only extract the values of A where X~=0, is it then possib...

environ 13 ans il y a | 5 réponses | 1

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Question

How to stop recurring error message if Ctrl+C doesn't work!? (help!!!)
Hi I tried to surf plot a discrete Laplacian matrix operator and it has broken MATLAB... I managed to close the figure, but t...

environ 13 ans il y a | 2 réponses | 0

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Question

Stopping fmincon based on timer
Hi, I asked this before and accepted an answer before having some trouble implementing the code, so I think I need to ask again....

environ 13 ans il y a | 3 réponses | 1

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Question

Can I impose a time limit on fmincon without editing the m-file?
I'm trying to compare different algorithms by imposing a time limit, however one of my algorithms calls fmincon and it seems imp...

environ 13 ans il y a | 1 réponse | 0

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Question

fmincon displays huge unwanted output text
Hi. Does anyone know why fmincon would ignore a 'Display','off' setting in the options? Here is my code: opt = optimset('Ma...

environ 13 ans il y a | 1 réponse | 0

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Réponse apportée
Non linear curve fitting by changing parameters
What is the blue curve? Usually a curve fitter algorithm requires a model (your h function) with specified parameter space (your...

environ 13 ans il y a | 0

Question

How to reshape a 16x16x16x16 matrix to 256x256 whilst maintaining consistency
Hi I have a pixel grid (16,16) and I've generated a matrix A whose (i,j,k,l)th element specifies a property of the pairing of...

environ 13 ans il y a | 1 réponse | 0

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Question

How to quantify the spread/separation of points on a circle
Hi, this may be a little vague I have a set of points in the unit circle and I want to quantify their separation, for example...

environ 13 ans il y a | 1 réponse | 0

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Question

lsqcurvefit.m ... how to find intermediate steps?
Hi I'm fitting using lsqcurvefit and the OUTPUT structure tells me there are 4 steps with 20 function evaluations before the ...

environ 13 ans il y a | 2 réponses | 0

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Radon Transform
If the ellipse has a uniform value the integral becomes the product between that value and the length of each beam through the e...

plus de 13 ans il y a | 1

Question

apply filter to a *circular* image
hello I'm trying to filter a circular image, the circle fits inside a square matrix, so for a 100x100 matrix the radius is 50...

plus de 13 ans il y a | 1 réponse | 0

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Question

Multiplying certain dimensions of two 3D matrices
Hi I've got two matrices, one 30x30x50 and one 30x30x80 I would like to multiply them in such a way that the result is a 5...

plus de 13 ans il y a | 3 réponses | 0

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Réponse apportée
merging column vectors from the loop in to a single matrix
Try something like: matrix = zeros(rows, columns); % preallocate your matrix for i = 1:columns column = [your code he...

presque 14 ans il y a | 1

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