Hello; I'm using the symbolic maths toolbox, specifically the fourier function. How do I access the positive and negative frequency components of the result separately ?
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Hello; I'm using the symbolic maths toolbox, specifically the fourier function. How do I access the positive and negative frequency components of the result separately ? I need to multiply the positive frequency components by -i and the negative frequency components by i, to compute the Hilbert transform. Note that Matlab's Hilbert function does not work with the symbolic maths toolbox.
Thank you.
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Star Strider
2016-11-30
The fourier function will give you the symbolic expression for the Fourier transform of your time- or spatial-domain function. You then are free to calculate and plot it for the frequency values you wish.
Also consider using simplify (with the 'Steps',10 name-value pair) and matlabFunction to create a function you can use in numerical computations.
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Star Strider
2016-12-1
This is my alternative approach. I don’t know what function you’re transforming, but in my experience, coding my own transform — as I did here — generally produceds the result I want.
The ‘problem’ with the fourier function is that it integrates from -Inf to +Inf. If your time-domain function has other than infinite support, this will cause problems. That’s the reason I generally code my transforms myself.
If I know the function has infinite support, fourier produces the appropriate result.
Walter Roberson
2016-11-30
Multiply the symbolic output by the Heaviside function on the frequency to get the positive components, and by Heaviside of negative of the frequency to get the negative components.
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