PGauss:

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   Computes the Gaussian form of the Legendre functions. 
   Will also compute the first derivatives, if requested.

   Because there is no zero indexing in Matlab, the P's are offset
   in the p matrix as follows:

                 n,m
   p(n+1,m+1) = P 

   Since version 1.
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   Form:
   [p, dP] = PGauss( nMax, mMax, theta )
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   ------
   Inputs
   ------
   nMax               max value of first index
   mMax               max value of second index
   theta              input value (usually an angle in rads)

   -------
   Outputs
   -------                              n,m
   p                  Gauss functions, P
                        n,m
   dP                 ?P    / ?(theta)      

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   References: Wertz, J., Spacecraft Attitude Determination and Control,
               Kluwer, 1976, pp. 781. 
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