1.2.16 `sm1.appell4'
--------------------

sm1.appell4(A|proc=P)
     ::  Returns the Appell hypergeometric system F_4 or F_C.

RETURN
     List

P
     Number

A
     List

   * Returns the hypergeometric system for the Lauricella function
     F_4(a,b,c1,c2,...,cn;x1,...,xn) where A =(a,b,c1,...,cn).  When
     n=2, the Lauricella function is called the Appell function F_4.
     The parameters a, b, c1, ..., cn may be rational numbers.

   *   * It does not call sm1 function appell4. As a concequence, when
     parameters are rational or symbolic, this function also works as
     well as integral parameters.


     [281] sm1.appell4([1,2,3,4]);
       [[-x2^2*dx2^2+(-2*x1*x2*dx1-4*x2)*dx2+(-x1^2+x1)*dx1^2+(-4*x1+3)*dx1-2,
       (-x2^2+x2)*dx2^2+(-2*x1*x2*dx1-4*x2+4)*dx2-x1^2*dx1^2-4*x1*dx1-2],
                                                                   equations
         [x1,x2]]                                      the list of variables

     [282] sm1.rank(@);
     4

