Determine the three components of the magnetic field vector at a single point.

## Usage

value = MakeMagGridPoint (cilm, a, r, lat, lon, [lmax, dealloc])


## Returns

value : float, dimension (3)
Vector components (r, theta, phi) of the magnetic field at (r, lat, lon).

## Parameters

cilm : float, dimension (2, lmaxin+1, lmaxin+1)
The real Schmidt semi-normalized spherical harmonic coefficients of the magnetic potential. 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].
a: float
The reference radius of the spherical harmonic coefficients.
r: float
The radius to evaluate the magnetic field.
lat : float
The latitude of the point in degrees.
lon : float
The longitude of the point in degrees.
lmax : optional, integer, default = lmaxin
The maximum spherical harmonic degree used in evaluating the function.
dealloc : optional, integer, 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

MakeMagGridPoint will compute the three components of the magnetic field vector at a single point. The input latitude and longitude are in degrees, and the output components are in spherical coordinates (r, theta, phi). The magnetic potential is given by

V = a Sum_{l=0}^lmax (a/r)^(l+1) Sum_{m=-l}^l C_{lm} Y_{lm},

and the vector magnetic field is

B = - Grad V.

The coefficients are referenced to a radius a, and the output values have the same units as the input spherical harmonic coefficients.

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