I hope that someday Octave will include more signal processing
functions. If you would like to help improve Octave in this area,
please contact bug-octave@che.utexas.edu
.
fft (a)
fft2 (a)
fftconv (a, b, N)
length (a) + length (b)
- 1
. If a and b are the coefficient vectors of two
polynomials, the returned value is the coefficient vector of the product
polynomial.
The computation uses the FFT by calling the function fftfilt
. If
the optional argument N is specified, an N-point FFT is used.
fftfilt (b, x, N)
fftfilt
filters x with the FIR filter
b using the FFT.
Given the optional third argument, N, fftfilt
uses the
overlap-add method to filter x with b using an N-point FFT.
filter (b, a, x)
[y, sf] = filter (b, a, x, si)
filter
uses the argument si as the initial state of the
system and and returns the final state in sf. The state vector is
a column vector whose length is equal to the length of the longest
coefficient vector minus one. If si is not set, the initial state
vector is set to all zeros.
freqz
[h, w] = freqz (b)
returns the complex frequency
response h of the FIR filter with coefficients b. The
response is evaluated at 512 angular frequencies between 0 and
The output value w is a vector containing the 512 frequencies.
[h, w] = freqz (b, a)
returns the complex
frequency response of the rational IIR filter whose numerator has
coefficients b and denominator coefficients a.
[h, w] = freqz (b, a, n)
returns the
response evaluated at n angular frequencies. For fastest
computation n should factor into a small number of small primes.
[h, w] = freqz (b, a, n, "whole")
evaluates the response at n frequencies between 0 and
ifft (a)
ifft2
sinc (x)