1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
|
/*Description
Convolve two vectors using the FFT for computation. c = fftconv (X, Y) returns a vector of length equal to 'length(X) + length (Y) - 1'. If X and Y are the coefficient vectors of two polynomials, the returned value is the coefficient vector of the product polynomial.
If the optional argument n is specified, an N-point FFT is used.
Calling Sequence
Y = fftconv(X, Y)
Y = fftconv(X, Y, n)
Parameters
X, Y: Vectors
Examples
fftconv([1,2,3], [3,4,5])
ans =
3. 10. 22. 22. 15.
*/
function y = fftconv(X, Y, n)
funcprot(0);
rhs = argn(2);
if(rhs<2 | rhs>3)
error("Wrong number of input arguments.");
end
shape_x = size(X);
shape_y = size(Y);
if (shape_x(1) ~= 1 || length(shape_x) ~= 2 || shape_y(1) ~= 1 || length(shape_y) ~= 2)
error('The inputs must be a vector');
end
nx=length(X);
ny=length(Y);
select(rhs)
case 2 then
n=nx + ny;
X=resize_matrix(X,1,n);
Y=resize_matrix(Y,1,n);
fftX=fft(X);
fftY=fft(Y);
y=fft(fftX.*fftY,1);
y=y(1:nx+ny-1);
case 3 then
n = 2^(fix(log2(nx+ny))+1);
X=resize_matrix(X,1,n);
Y=resize_matrix(Y,1,n);
fftX=fft(X);
fftY=fft(Y);
y=fft(fftX.*fftY,1);
y=y(1:nx+ny-1);
end
y=clean(y);
endfunction
|
