MagCalc is a Palm OS program for computing the Earth's magnetic field at any location based on the US DoD magnetic field model.

MagCalc computes the total intensity, horizontal intensity, magnetic declination (or variation) and dip.

It also computes the annular rate of change of each these parameters.

These calculations are performed based on user entered latitude, longitude, altitude above sea level and date.

The complete source code can be downloaded from the author's web site.