Community Profile # Douglas Brenner

42 total contributions since 2016

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Matlab crashes but Octave doesn't
Give that man a cigar and thank you very much. pinv(A)*b work as I suspect doing the LU decomposition manually would.

2 years ago | 0

Question

Matlab crashes but Octave doesn't
The program below runs in Octave but crashes Matlab 2014. Mathworks won't help because my contract has run out. Any ideas would ...

2 years ago | 3 answers | 0

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Question

creating a vector where each element needs to be calculated before hand
Can I creat Z in a single statement which doesn't require explicit calculation of each element or should I just use a loop? Z =...

2 years ago | 1 answer | 0

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Question

Creating a matrix one row at a time
In each iteration of a loop I create a row vector Y = [1,2,3,4,5]; then I want to add the Y's to a matrix one line at a time;...

2 years ago | 2 answers | 0

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help with fitlm (least squares fit)
I could try a Gaussian fit. That would work for me. Do you have an example for that? Thanks.

2 years ago | 0

help with fitlm (least squares fit)
Your demo crashed it as well.

2 years ago | 0

| accepted

help with fitlm (least squares fit)
X = [1,2,3,4,5] Y = [1,5,6,4,2] yFit = polyfit(X,Y, 2) Matlab itself crashed.

2 years ago | 0

Question

help with fitlm (least squares fit)
I don't understand how to use fitlm if indeed that's the right function to use. I want to fit 5 sets of data to the function y ...

2 years ago | 3 answers | 0

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Why would circshift stop working.
I had been transposing matrics and released this morning as I was waking that this must have been the problem. Thanks.

2 years ago | 0

Question

Why would circshift stop working.
There is no evidence that circshift is working. The two plots are the same whereas yesterday a clear shift in the plots can be s...

2 years ago | 3 answers | 0

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matrix multiplication dimension issues
Found the answer. n is not the number of points in a spectrum but the number of spectra. Thanks for trying

2 years ago | 0

matrix multiplication dimension issues
The basic science is to take two spectra and perform a 2d cross correlation resulting in a real and a complex matrix. They shoul...

2 years ago | 0

Question

matrix multiplication dimension issues
I have an article which I'm trying to follow. It calculates two matricies that I called synch and async. I read two files into...

2 years ago | 3 answers | 0

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Question

Replacing for loops with matrix math.
How can I simplify this code. I.e remove the loops and replace them with matrix math. for i=1:3 for j = i:num_pts - ...

2 years ago | 1 answer | 0

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Question

Getting off diagonals after calculating a correlation matrix
The code below gives the first off diagonals of the correlation computation in line 6. How do I get the others? testm1 = [1...

2 years ago | 0 answers | 0

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reducing number of operations in matrix multiplication
Clearly but that was the suggested solution. Trying for i=1:2 diags1{i} = testm(i+1:num_pts-i-1 ,2).*testm(1:num_pts-i-1,2...

2 years ago | 0

reducing number of operations in matrix multiplication
testm = [1,2,3,4,5;2,4,5,7,10] num_pts = 5; testm = transpose(testm) corr = testm(:,2)*testm(:,2)' diag(...

2 years ago | 0

Question

reducing number of operations in matrix multiplication
I want to perform the follow operation: synch = spect1(1:num_pts ,2)*spect2(1:num_pts,2)'; The problem is that num_pts > 300,0...

2 years ago | 2 answers | 0

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Question

Why does this loops produce a matrix?
code waves = [393.029, 414.386, 427.176, 516.748, 526.953, 640.000]; l = length(waves); for i = 1:l L = wave...

2 years ago | 1 answer | 0

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dimension error with * operator
The paper from which I got the code uses * and that works in this line: synch = C1(:)*C1(:)'/(delta-2). Not only do I not get ...

2 years ago | 0

Question

dimension error with * operator
This line of code: asynch = C1(:)*N(:)*C(:)'/(delta-2) throws an error: Error using * Inner matrix dimensions must agree. Th...

2 years ago | 3 answers | 0

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error trying to run xcorr2.
This is the error: Cell contents reference from a non-cell array object. Error in cell2mat (line 42) But if I try a different...

2 years ago | 0

Question

error trying to run xcorr2.
This is my code D1 = cell2mat(data1{2}); %D1 and D2 are 1x3 cells of doubles D2 = cell2mat(data2{2}); c = xcorr2(D1,D2); It ...

2 years ago | 1 answer | 0

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Getting non-existent pixel values
Didn't work Index exceeds matrix dimensions. Error in stddev (line 51) greenChannel = b(:, :, 2); Is there a green pla...

4 years ago | 0

Question

Getting non-existent pixel values
After the following code, an image is displayed. It is black, white and red. However, if I use hpimpixelinfo(2) on the image I ...

4 years ago | 2 answers | 0

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Question

image processing algorithm for filling
I am going to try but in the meantime if anybody wants to help ... I have a 2-D image in black, white and red. Going across e...

4 years ago | 0 answers | 0

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Question

using greythresh and im2bw
Figure 1 is great but BW is all black. Thoughts? Thanks figure (1) scaled = 255 * width/MAX; imshow(uint8(scal...

4 years ago | 1 answer | 0

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Question

What does this error for hist mean?
Attempt to execute SCRIPT hist as a function: /Users/douglasbrenner/Documents/MATLAB/hist.m Error in extractedge (line 3...

4 years ago | 2 answers | 0