Answered

fft2: Frequency and wavenumber

Take a look at my post here for an idea of what is output from FFT2: <http://www.mathworks.com/matlabcentral/answers/24965-ff...

fft2: Frequency and wavenumber

Take a look at my post here for an idea of what is output from FFT2: <http://www.mathworks.com/matlabcentral/answers/24965-ff...

10 years ago | 0

| accepted

Answered

Gaussian FFT

Try plotting the absolute value of the frequency domain amplitudes... when your Gaussian is not centered at time 0, the phase ma...

Gaussian FFT

Try plotting the absolute value of the frequency domain amplitudes... when your Gaussian is not centered at time 0, the phase ma...

10 years ago | 1

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Answered

Anyone using MATLAB on a LINUX OS??

Works fine for me on Redhat... running it on a 12-core, 96GB machine at work. Any simple-ish benchmarks you looking to test/meas...

Anyone using MATLAB on a LINUX OS??

Works fine for me on Redhat... running it on a 12-core, 96GB machine at work. Any simple-ish benchmarks you looking to test/meas...

10 years ago | 0

Answered

I want to plot PSD for my input data(meters)

If you are measuring displacement in meters in the time domain, then your frequency domain amplitudes (after performing the FFT)...

I want to plot PSD for my input data(meters)

If you are measuring displacement in meters in the time domain, then your frequency domain amplitudes (after performing the FFT)...

10 years ago | 0

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Answered

Difference between fft and manually coding for a fourier transform

You are not correctly defining the frequencies "k" that are associated with the amplitudes in the frequency domain, but it start...

Difference between fft and manually coding for a fourier transform

You are not correctly defining the frequencies "k" that are associated with the amplitudes in the frequency domain, but it start...

10 years ago | 0

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Answered

Scaling of fft output?

See my answer here: <http://www.mathworks.com/matlabcentral/answers/15770-scaling-the-fft-and-the-ifft> In order to conse...

Scaling of fft output?

See my answer here: <http://www.mathworks.com/matlabcentral/answers/15770-scaling-the-fft-and-the-ifft> In order to conse...

10 years ago | 0

Answered

Is there any alternative to if statements inside for loops?

Do you pre-allocated "Pin", if not... then before the for-loops put: Pin = zeros(8760,Ni); The inside of your for-loops ...

Is there any alternative to if statements inside for loops?

Do you pre-allocated "Pin", if not... then before the for-loops put: Pin = zeros(8760,Ni); The inside of your for-loops ...

10 years ago | 0

Answered

impulse response interpretation

I reran through the process of generating the Frequency Response data (G) using your code and the one from the FEX just to see i...

impulse response interpretation

I reran through the process of generating the Frequency Response data (G) using your code and the one from the FEX just to see i...

10 years ago | 0

Answered

from time domain to frequency domain and back to time domain

Your "X" has shifted the zero frequency amplitude to the center. You need to use *ifftshift* to get it back where Matlab expects...

from time domain to frequency domain and back to time domain

Your "X" has shifted the zero frequency amplitude to the center. You need to use *ifftshift* to get it back where Matlab expects...

10 years ago | 0

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Answered

I cant generate a square wave in matlab using the square wave command

If you dont have the Signal Processing Toolbox, will the following work as an alternative: y = sign(sin(2*pi*100*t));

I cant generate a square wave in matlab using the square wave command

If you dont have the Signal Processing Toolbox, will the following work as an alternative: y = sign(sin(2*pi*100*t));

10 years ago | 1

Answered

obtain the Impulse response from a frequency response

N = 1000; % Number of samples df = 20; % Frequency increment (in Hertz) Nyq = 10000; % Nyquist Frequency (in Hertz) ...

obtain the Impulse response from a frequency response

N = 1000; % Number of samples df = 20; % Frequency increment (in Hertz) Nyq = 10000; % Nyquist Frequency (in Hertz) ...

10 years ago | 4

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Answered

Can my integration code for an accelerometer data work for a Square wave?

Instead of trying to convert using your code, try mine located here: <http://www.mathworks.com/matlabcentral/answers/21700-fi...

Can my integration code for an accelerometer data work for a Square wave?

Instead of trying to convert using your code, try mine located here: <http://www.mathworks.com/matlabcentral/answers/21700-fi...

10 years ago | 0

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Answered

Help With Plot Legend

If you are just trying to apply the 3 legend strings to 3 lines on a plot, then all you need to do is: legend(cell) Take...

Help With Plot Legend

If you are just trying to apply the 3 legend strings to 3 lines on a plot, then all you need to do is: legend(cell) Take...

10 years ago | 0

Answered

What does x(1,:) do in MATLAB ?

"a0" is the Fourier Transform of the first row of "at" at(2,:) % gives the second row at(3,:) % gives the third row (and s...

What does x(1,:) do in MATLAB ?

"a0" is the Fourier Transform of the first row of "at" at(2,:) % gives the second row at(3,:) % gives the third row (and s...

10 years ago | 12

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Answered

Interpreting frequency using pwelch function

1/26.0893 years per sample equals roughly 1208771.41 seconds per sample, which is roughly equivalent to an Fs of 8.27286276e-07 ...

Interpreting frequency using pwelch function

1/26.0893 years per sample equals roughly 1208771.41 seconds per sample, which is roughly equivalent to an Fs of 8.27286276e-07 ...

10 years ago | 0

Answered

if statement for range of array values

I think what you might be after is something like: if all(x(i-1:i+1) < xmax) || all(y(i-1:i+1) < ymax) % something e...

if statement for range of array values

I think what you might be after is something like: if all(x(i-1:i+1) < xmax) || all(y(i-1:i+1) < ymax) % something e...

10 years ago | 0

Answered

Question about fft

The way it is implemented above, the value at 0 frequency is just the sum of your signal from -1 seconds to 1 second (you have a...

Question about fft

The way it is implemented above, the value at 0 frequency is just the sum of your signal from -1 seconds to 1 second (you have a...

10 years ago | 0

Answered

quick easy question

It looks like "t" is an array of numbers, therefore you need to incorporate a "." before you multiply "(B1*cos*(Omega_d*t) + B2*...

quick easy question

It looks like "t" is an array of numbers, therefore you need to incorporate a "." before you multiply "(B1*cos*(Omega_d*t) + B2*...

10 years ago | 0

Answered

Create a array of 1 and -1

Not the most efficient, but: >> a=nchoosek([1,2,3,4,5,6,7,8],4); >> b = ones(size(a)); >> b(mod(a,2)==0) = b(mod(a,2)==0)...

Create a array of 1 and -1

Not the most efficient, but: >> a=nchoosek([1,2,3,4,5,6,7,8],4); >> b = ones(size(a)); >> b(mod(a,2)==0) = b(mod(a,2)==0)...

10 years ago | 0

Answered

FFT single-sided amplitude spectrum plot spike at 1Hz of accelerometer data

As a general rule of thumb, I will remove any trend and/or mean from the data before I run it through FFT.

FFT single-sided amplitude spectrum plot spike at 1Hz of accelerometer data

As a general rule of thumb, I will remove any trend and/or mean from the data before I run it through FFT.

10 years ago | 0

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Answered

why fgetl read spaces?

If they are all just numbers on the line, then converted the string to numeric should do the trick new_t = str2num(t);

why fgetl read spaces?

If they are all just numbers on the line, then converted the string to numeric should do the trick new_t = str2num(t);

10 years ago | 1

Answered

Matrix of statuses or matching; discrete one-to-one mapping

You can't do this with any old NxK matrix, it must be a square NxN matrix. Otherwise your condition, that the sums of individual...

Matrix of statuses or matching; discrete one-to-one mapping

You can't do this with any old NxK matrix, it must be a square NxN matrix. Otherwise your condition, that the sums of individual...

10 years ago | 0

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Answered

plotting the frequency spectrum

Your "f" looks off. For your configuration (which uses fftshift): N = length(y); dt = x(2)-x(1); % Time increment Nyq = 1...

plotting the frequency spectrum

Your "f" looks off. For your configuration (which uses fftshift): N = length(y); dt = x(2)-x(1); % Time increment Nyq = 1...

10 years ago | 0

Answered

How to extract correct FFT?

Just to eliminate a few things, try this: dt = time(2)-time(1); Fs = 1/dt; M = length(gage); N = pow2(nextpow2(M)); ...

How to extract correct FFT?

Just to eliminate a few things, try this: dt = time(2)-time(1); Fs = 1/dt; M = length(gage); N = pow2(nextpow2(M)); ...

10 years ago | 0

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Answered

Alternative to using "unix(sprintf('ls %s/*/*/*.out',pathname))" ?

I ran a test... Running this from Matlab: [~,List] = unix(sprintf('ls %s/*/*/*.out',pathname)); And then doing some m...

Alternative to using "unix(sprintf('ls %s/*/*/*.out',pathname))" ?

I ran a test... Running this from Matlab: [~,List] = unix(sprintf('ls %s/*/*/*.out',pathname)); And then doing some m...

10 years ago | 0

| accepted

Answered

How to create 'density' plot from 2d scatter data

Check out the example for *hist3* in the Help navigation window... maybe useful here.

How to create 'density' plot from 2d scatter data

Check out the example for *hist3* in the Help navigation window... maybe useful here.

10 years ago | 1

Answered

Sequence within a sequence

To beat a dead horse... I thought I remembered a version by Walter using *cumsum*, but I couldn't find the link. Here's my at...

Sequence within a sequence

To beat a dead horse... I thought I remembered a version by Walter using *cumsum*, but I couldn't find the link. Here's my at...

10 years ago | 1

Answered

Calculating energy

In order to obtain energy, do not even worry about the power. Just do this: Using "*y*" and "*f*" from the output of spectrog...

Calculating energy

In order to obtain energy, do not even worry about the power. Just do this: Using "*y*" and "*f*" from the output of spectrog...

10 years ago | 1

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