Function:	VECTOR_INPROD

 Purpose:      Compute Vector Inner Product

 File:		vector_prod.shl

 Class:	Math

Author:       Albrecht de Jonge

 Use: doubleprecision function VECTOR_INPROD( 
	X,	I	doubleprecision
	Y )  	I	doubleprecision

       X, Y            two 3-dimensional vectors
       VECTOR_INPROD   the inner product ( X dot Y )
 
       Mainly meant as a shorthand for
               P = X(1) * Y(1) + X(2) * Y(2) + X(3) * Y(3)
 
 Update        901113 DK, adapted to GIPSY