Described in table lookup terms, the table is and interp1 looks up the elements of xi in x, and, based upon their locations, returns values yi interpolated within the elements of Y. Interpolation is the same operation as table lookup.

This function is shown below, along with the relationship between vectors x, Y, xi, and yi. It finds values at intermediate points, of a one-dimensional function that underlies the data. The interp1 command interpolates between data points. Returns the scalar extrapval for out of range values. Uses the specified method to perform extrapolation for out of range values. For all other methods, interp1 performs extrapolation for out of range values. If Y is a matrix, then the interpolation is performed for each column of Y and yi is length(xi)-by- size(Y,2).ДЄssumes that x = 1:N, where N is the length of Y for vector Y, or size(Y,1) for matrix Y.ДЇor the 'nearest', 'linear', and 'v5cubic' methods, interp1(x,Y,xi,method) returns NaN for any element of xi that is outside the interval spanned by x. The vector x specifies the points at which the data Y is given. Returns vector yi containing elements corresponding to the elements of xi and determined by interpolation within vectors x and Y. One-dimensional data interpolation (table lookup) Interp1 (MATLAB Functions) MATLAB Function Reference

Matlab interp1