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Thread Subject:
S Functions or Matlab function blocks

Subject: S Functions or Matlab function blocks

From: Aravind VJ

Date: 15 Jul, 2012 11:34:27

Message: 1 of 2

Hello

I am an electronics engineer. Interested in using simulink. I am trying to do FFT inside an S function block (I am new to simulink, but have some experience with matlab). Somone please guide me on this

Regards
Aravind

Subject: S Functions or Matlab function blocks

From: Phil Goddard

Date: 15 Jul, 2012 14:00:07

Message: 2 of 2

There is an FFT block in the Signal Processing Blockset is you have access to it.

Otherwise you could use either a MATLAB Fcn block or an S-Function.

Assuming the input signal is sample based (i.e. scalar at each time step), then the first thing you need to do is buffer the signal into an appropriate length vector before performing the fft.
Within an S-function you'd do that with a DWork vector.
Within a MATLAB Fcn block you'd need to use a persistent variable.

If you intend using the MATLAB fft function then within a MATLAB Fcn block you'll need to define fft as being coder.extrinsic.

Phil.

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