Find CTFT using MatLab


by olen501
Tags: ctft, matlab
olen501
olen501 is offline
#1
Feb28-08, 10:58 PM
P: 6
Does anyone know how to find the CTFT of a function using MatLab? I know MatLab has a built in function called fft that finds the fast fourier transform, but I don't know how to use the fft to find the CTFT. Can anyone help me out?
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DefaultName
DefaultName is offline
#2
Feb29-08, 07:36 PM
P: 181
You can do something like:

x = cos(2*pi*f*t);
ft = fftshift(fft(x));

Then you must plot over the proper frequency range. This is most likely why you can't work with fft and get the right results.
quadraphonics
quadraphonics is offline
#3
Feb29-08, 08:13 PM
P: 270
When you say CTFT, you mean the Continous-Time Fourier Transform? The only way to do that on a computer is using symbolic math. You can't directly represent a continuous function inside the computer, and so you can't directly compute its Fourier Transform. So, supposing you have an expression for the function in question, you can feed that into the symbolic math toolbox, and have it give you an expression for the answer. I haven't used Matlab's symbolic math capabilities very much, so I can't comment further, but you might also just use The Integrator ( http://integrals.wolfram.com/index.jsp ). The downside to these approaches is that they tend not to be terribly good at simplifying the results, so you're apt to get a huge string of special functions that all end up cancelling eachother out. Often, the process of simplifying the output of these symbolic math systems can be as laborious as simply doing the integral yourself in the first place. They are good resources if you're stuck or want to check your answers, though...

maverick280857
maverick280857 is offline
#4
Mar5-08, 02:29 AM
P: 1,772

Find CTFT using MatLab


Yes, better to use a package designed with symbolic computations in mind...like Mathematica.
olen501
olen501 is offline
#5
Mar7-08, 01:26 AM
P: 6
Thanks
olen501
olen501 is offline
#6
Mar7-08, 01:29 AM
P: 6
thanks


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