Interpolation

Syntax: vout = INTERPOLATE(x,y,xout,'SPLINE')
vout = INTERPOLATE(x,y,xout,'LINEAR')
vout = INTERPOLATE(x,y,xout,'LAGRANGE')
vout = INTERPOLATE(x,y,xout,'FC')
mout = SPLINTERP(x,y,n)

The INTERPOLATE function interpolates the data contained in vector x, the independent variable, and vector y, the dependent variable. x must be strictly monotonically increasing. The interpolant locations are given in vector xout. The INTERPOLATE function will return the interpolated values as a vector with the same length as xout. The algorithm that is employed depends on the keyword that is used.

The SPLINTERP function interpolates the data contained in vector x, the independent variable, and vector y, the dependent variable. There are no restrictions on x, it doesn't even need to be increasing. The number of interpolant locations is given in scalar n, which must be greater than 1. The output of the SPLINTERP function is a matrix with n rows and 2 columns. The first column will contain the output locations and the second column the interpolated values at those locations.

An interpolated curve will always pass through the original data points. If it is not important that the curve pass through the original data, use the SMOOTH function, unless your independent variable is not monotonically increasing. In that case, use the SPLSMOOTH function.

Linear interpolation
Spline interpolation
Lagrange interpolation
Fritch-Carlson interpolation
SPLINTERP function
2D interpolation