multiresolution_subtract.m

Subtracts vectors @ different resolution.

Description

This function will subtract two vectors x and y at different resolutions x_grid and y_grid and give an output at the lower resolution. Either x or y may be the low-resolution vector. Vectors may be unsorted according to x_grid and y_grid, but they will be sorted using sort_by_x.m.

Function operates very fast with decent accuracy, but has option to operate slowly at increased accuracy.

• MATLAB release: MATLAB 6.5.1 (R13SP1)
• Other requirements: None

[Jan Simon]

z = multiresolution_subtract(x, x_grid, y, y_grid)
is equivalent to the Matlab method:
z = interp1(x_grid, x, y_grid, 'nearest') - y;
For x = [1x600] and y = [1x110], the INTERP1 method takes 14% of multiresolution_subtract (in fast mode). Therefore this function is not "very fast". And there are even faster methods for interpolation than INTERP1.
The helper function sort_by_x is really slow compared to Matlab's SORT (see comments for your FEX: 6424).
If x and y are smooth, a linear interpolation can be more useful: z = interp1(x_grid, x, y_grid, 'linear') - y;
It works, has a help text, H1-line not useful, author and date are mentioned.