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makegridpoint.doc
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makegridpoint.doc
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Evaluate a real function expressed in real spherical harmonics at a set of
points.
Usage
-----
value = MakeGridPoint (cilm, lat, lon, [lmax, norm, csphase, dealloc])
Returns
-------
value : float, ndarray
Value of the function at (lat, lon).
Parameters
----------
cilm : float, dimension (2, lmaxin+1, lmaxin+1)
The real spherical harmonic coefficients of the function. The coefficients
C0lm and C1lm refer to the cosine (Clm) and sine (Slm) coefficients,
respectively, with Clm=cilm[0,1,m] and Slm=cilm[1,l,m].
lat : float, array_like
The geocentric latitude of the point in degrees.
lon : float, array_like
The longitude of the point in degrees.
lmax : integer, array_like, optional, default = lmaxin
The maximum spherical harmonic degree used in evaluating the function.
norm : integer, array_like, optional, default = 1
1 (default) = Geodesy 4-pi normalized harmonics; 2 = Schmidt semi-normalized
harmonics; 3 = unnormalized harmonics; 4 = orthonormal harmonics.
csphase : integer, array_like, optional, 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 : integer, array_like, optional, 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 given
set of points. The input latitudes and longitudes are in degrees, and the
maximum degree used in evaluating the function is the smaller of lmaxin and
lmax. 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.