Reconstruction of vector field from spherical harmonic coefficients

[ronslow]

The JGM3 model of earth's gravity is expressed in the form of coefficients C and S to Legendre polynomials in r, theta and phi which give the gravitational potential

U = \sum\sum CV + SW

Can anyone tell me the algorithm for calculating acceleration vector g(r, theta, phi) from the coefficients, i.e. \Delta.U expressed as a polar vector?

Thanks

Robert

[ronslow]

Answer here:
http://homepage.mac.com/hanspeterschaub/work/Papers/UnderGradStudents/MagneticField.pdf