Matlab Linear Interpolation

More generally, linear interpolation is given by

$$w(n+\eta) = (1-\eta)w(n) + (\eta)w(n+1)$$

where $n$ is the integer part of the original index value, and $\eta$ is the fractional part, indicating how far from $n$ we want to interpolate,

$$\eta = x-n.$$

Below is a Matlab function which implements linear interpolation.

function y = lininterp(w, x);
% LININTERP Linear interpolation.
%   Y = LININTERP(W, X) where Y is the output, 
%   X is the input indeces, not necessarily 
%   integers, and W is the transfer function 
%   indexed by X.

n = floor(x);
eta = x-n;
w = [w 0];
y = (1-eta).*w(n) + eta.*w(n+1);
y = y(1:length(x));