interpft - 1-D interpolation using FFT method
Syntax
y = interpft(x,n)
y = interpft(x,n,dim)
Description
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.
Algorithm
The interpft command uses the FFT method. The original
vector x is transformed to the Fourier domain using fft and
then transformed back with more points.
Examples
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')See Also
interp1
 | interp3 | | interpn |  |
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