MakeGridPoint (Fortran)

Evaluate a real function expressed in real spherical harmonics at a single point.

Usage

value = MakeGridPoint (cilm, lmax, lat, lon, norm, csphase, dealloc)

Parameters

value : output, real(dp)

Value of the function at (lat, lon).

cilm : input, real(dp), dimension (2, lmax+1, lmax+1)

The real spherical harmonic coefficients of the function. The coefficients C1lm and C2lm refer to the cosine (Clm) and sine (Slm) coefficients, respectively, with Clm=cilm(1,l+1,m+1) and Slm=cilm(2,l+1,m+1).

lmax : input, integer(int32)

The maximum spherical harmonic degree used in evaluating the function.

lat : input, real(dp)

The latitude of the point in degrees.

lon : input, real(dp)

The longitude of the point in degrees.

norm : input, optional, integer(int32), default = 1

1 (default) = Geodesy 4-pi normalized harmonics; 2 = Schmidt semi-normalized harmonics; 3 = unnormalized harmonics; 4 = orthonormal harmonics.

csphase : input, optional, integer(int32), default = 1

1 (default) = do not apply the Condon-Shortley phase factor to the associated Legendre functions; -1 = append the Condon-Shortley phase factor of (-1)^m to the associated Legendre functions.

dealloc : input, optional, integer(int32), default = 0

0 (default) = Save variables used in the external Legendre function calls. (1) Deallocate this memory at the end of the funcion call.

Description

MakeGridPoint will expand a function expressed in spherical harmonics at a single point. The input latitude and longitude are in degrees. The employed spherical harmonic normalization and Condon-Shortley phase convention can be set by the optional arguments norm and csphase; if not set, the default is to use geodesy 4-pi normalized harmonics that exclude the Condon-Shortley phase of (-1)^m.

See also

makegridpointc, makegriddh, makegriddhc, makegridglq, makegridglqc