1-D interpolation using FFT method
y = interpft(x,n)
y = interpft(x,n,dim)
y = interpft(x,n) returns
the vector y that contains the value of the periodic
function x resampled to n equally
spaced points.
If length(x) = m, and x has
sample interval dx, then the new sample interval
for y is dy = dx*m/n. Note that n cannot
be smaller than m.
If X is a matrix, interpft operates
on the columns of X, returning a matrix Y with
the same number of columns as X, but with n rows.
y = interpft(x,n,dim) operates
along the specified dimension.
Interpolate a triangle-like signal using an interpolation factor of 5. First, set up signal to be interpolated:
y = [0 .5 1 1.5 2 1.5 1 .5 0 -.5 -1 -1.5 -2 -1.5 -1 -.5 0]; N = length(y);
Perform the interpolation:
L = 5;
M = N*L;
x = 0:L:L*N-1;
xi = 0:M-1;
yi = interpft(y,M);
plot(x,y,'o',xi,yi,'*')
legend('Original data','Interpolated data')