EQNSOL computes the date of equinoxes and solstices for the input year.This is based upon the formulas given by Jean Meeus in his "Astronomical Algorithms". The date is computed in Julian Date.
This function take in JD2CAL function of "Geodetic Toolbox" by Mike Craymer (ID:15285) to convert Julian Date into Gregorian calendar date.
Great function! While the level of accuracy does not affect my needs, you may want to let others know if they are in need to to the minute or second, may want to validate the results. Comparing this functions results to the US Naval Observatory, the results differ by approximately 1-minute. I'm guessing this is an artifact of matlab and complier precision. Anything dealing with astronomy and floating point precision becomes significant.