Bi-Linear Interpolation

Brett Towler, USFWS, 1/11/2015

Bi-linear interpolation is an extension of linear interpolation for interpolating functions of two variables (e.g., x and y) on a regular 2D grid. The procedure, below, performs linear interpolation first in one direction, and then again in the other direction. Note that although each step is linear, the interpolation as a whole is not linear but instead quadratic. The code below would work for any size matrix.

1. Given the system [X, Y, XYZ]

X, Y are in ascending order of, any values representative of your system.

2. Construct the Bi-linear matrix