interp

% error: y = interp(x, q [, n [, Wc]])
%
% Upsample the signal x by a factor of q, using an order 2*q*n+1 FIR
% filter. Note that q must be an integer for this rate change method.
% n defaults to 4 and Wc defaults to 0.5.
%
% Example
%                                          % Generate a signal.
%    t=0:0.01:2; x=chirp(t,2,.5,10,'quadratic')+sin(2*pi*t*0.4); 
%    y = interp(x(1:4:length(x)),4,4,1);   % interpolate a sub-sample
%    stem(t(1:121)*1000,x(1:121),'-g;Original;'); hold on;
%    stem(t(1:121)*1000,y(1:121),'-r;Interpolated;');
%    stem(t(1:4:121)*1000,x(1:4:121),'-b;Subsampled;'); hold off;
%
% See also: decimate, resample