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John


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Matlab!!!!!

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How to detect rise and fall of a sparse signal?
I have a signal where at certain points, it rises from 0 and goes back down to 0 for a given peak. I need the indices of the fi...

plus de 11 ans il y a | 1 réponse | 1

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Question


FFT of a signal that is compressed
If I have a signal of size 2048, is it possible to compress/scale the signal down to size 1024 such that there is some relations...

plus de 11 ans il y a | 1 réponse | 0

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réponse

Question


Dropping Wavelet Coefficients After Wavelet Transform
I have a 512 sample signal that I pass through a wavelet transform. I get a series of wavelet coefficients some of which are s...

plus de 11 ans il y a | 1 réponse | 0

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Question


Fit a signal into smaller window while maintaiing proportion
I have a random signal of 2048 points. There are several peaks spread out (maybe 10). The rest are all zeros or have very low ...

plus de 11 ans il y a | 1 réponse | 0

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Question


Two algorithms with the same complexity in Matlab
I was able to implement two algorithms and they have the same complexity in Matlab. One algorithm uses vectorized code and the ...

plus de 11 ans il y a | 3 réponses | 0

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Réponse apportée
Matlab FFT vs MEX FFTW
I was doing the same analysis comparing Matlab's built in function with a variety of FFT algorithms some of which I wrote. It t...

plus de 11 ans il y a | 0

Question


Converting between zero padded and non zero padded FFT
I have a signal, x = [1 2 3 4]. I have the fft(x) which is 10.0000 -2.0000 + 2.0000i -2.0000 ...

plus de 11 ans il y a | 2 réponses | 0

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Question


Need FFT Code for Matlab (not built in)
Does anyone have FFT code for Matlab? I don't want to use the built-in Matlab function.

plus de 11 ans il y a | 4 réponses | 1

4

réponses

Question


Fast Fourier Transform Question in Matlab
I have a signal with 8192 samples with lots of intermittent 0s. I want to compute the FFT of this signal however I don't want t...

plus de 11 ans il y a | 1 réponse | 0

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Question


Wavelet Pack Decomposition - Is there a faster way?
I have to do multi-level wavelet decomposition. I've tried using dwt and calling it recursively. I've also tried using wpdec...

plus de 11 ans il y a | 1 réponse | 0

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Question


Modifying a large sparse matrix efficiently
I have a lot of zero elements in the matrix but I also I have a lot of elements that are small enough that I want to zero them o...

plus de 11 ans il y a | 4 réponses | 1

4

réponses

Question


Concatenating large matrices - out of memory
I have four 4096x4096 sparse matrices namely A, B, C, and D and they only have elements on the diagonal. I tried to make a ma...

plus de 11 ans il y a | 2 réponses | 0

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Question


What does it mean for a signal to be sparse? Is that the same thing as sparse matrix in Matlab?
Are these the same thing? Does a sparse signal contain a lot of zeros with some portion being the relevant part?

plus de 11 ans il y a | 1 réponse | 0

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Question


Two algorithms that give me different timing results on two different machines
What could possibly be going on? I ran algorithm 1 and 2 in Matlab on one machine a few thousand times. Algorithm 1 always d...

plus de 11 ans il y a | 2 réponses | 0

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réponses

Question


What do wavelet transform coefficients of zero mean?
I am new to wavelet transforms. I have a signal of length 128. I passed it to the Matlab wavelet function 'dwt' using a haar f...

plus de 11 ans il y a | 1 réponse | 0

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Question


How to conserve memory for Fast Fourier Results?
I have a 16384 vector FFT which is exactly 2^14. This vector is multiplied by another vector to get the results I need. Thi...

plus de 11 ans il y a | 1 réponse | 0

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Question


Is there a better to multiply matrices with is pattern?
I have a 2 x 2 matrix A = [1 2; 3 4] and a 100 x 1 column vector B = [1 2 3 4 5 6 . . . 100]' and I want to multiply matrix A ...

plus de 11 ans il y a | 2 réponses | 0

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Question


How to efficiently implement algorithm similar to FFT?
I am implementing an algorithm similar to FFT. The only difference is that I'm using my own custom twiddle factors for the butt...

plus de 11 ans il y a | 1 réponse | 0

1

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Question


Is there a faster way to concantenate this matrix?
I have a matrix A that is initially a 2 x 2 matrix. I compute a new value of A and call this A_new which is also a 2 x 2 matr...

plus de 11 ans il y a | 2 réponses | 0

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Question


How to properly measure computational complexity (run-time) in Matlab?
Basically, I am implementing an algorithm that has the same computational complexity as the FFT function in Matlab? The complex...

plus de 11 ans il y a | 1 réponse | 0

1

réponse

Question


How to optimize the multiplication of large matrices in Matlab?
I have 2 matrices A, B, and vector C that I need to multiply. They are fairly large. Matrix A = 10000x10000 Matrix B = 10...

plus de 11 ans il y a | 3 réponses | 0

3

réponses

Question


How to copy a sub-matrix/vector along diagonal of a larger matrix with varying number of sub-matrices?
I want to create a matrix below where I copy A = [1 2 3] allow the diagonal of a matrix. [ 1 2 3 0 0 0 0 0 0 0 0 0 0 0 1 2...

plus de 11 ans il y a | 4 réponses | 0

4

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