Fast 2-dimensional interpolation

This function performs 2-dimensional interpolation similar to MATLAB's built-in function interp2 with a considerable speed advantage.

qinterp2 may only be used with evenly-spaced, monotonically increasing X and Y library arrays. In addition, there is little error checking on these inputs, as qinterp2's speed boost is derived from avoiding manipulation of these arrays. See the attached image for how interp2 and qinterp2 compare vs. input length. The test was performed on a 2.4GHz Intel Windows XP machine running MATLAB 7 R14SP3.

See file id 10286 (Fast interpolation) for the one-dimensional version of this file.