S =
WlsToS(wls)
Converts a list of wavelengths to a [start delta num]
description. Wavelengths must be evenly spaced.
4/17/02 dhb Handle special case of one wavelength passed.
Delta argument is arbitrarily set to 0 for this case.
7/11/03 dhb Handle case the wls is passed in struct format.
1/3/12 dhb Fix check for evenly spaced wavelengths.
Psychtoolbox/PsychColorimetric/WlsToS.m