1.2.17 `sm1.rank'
-----------------

sm1.rank(A|proc=P)
     ::  Returns the holonomic rank of the system of differential
     equations A.

RETURN
     Number

P
     Number

A
     List

   * It evaluates the dimension of the space of holomorphic solutions
     at a generic point of the system of differential equations A.  The
     dimension is called the holonomic rank.

   * A is a list consisting of a list of differential equations and a
     list of variables.

   * `sm1.rrank' returns the holonomic rank when A is regular
     holonomic. It is generally faster than `sm1.rank'.


     [284]  sm1.gkz([  [[1,1,1,1],[0,1,3,4]],  [0,2] ]);
     [[x4*dx4+x3*dx3+x2*dx2+x1*dx1,4*x4*dx4+3*x3*dx3+x2*dx2-2,
       -dx1*dx4+dx2*dx3, -dx2^2*dx4+dx1*dx3^2,dx1^2*dx3-dx2^3,-dx2*dx4^2+dx3^3],
      [x1,x2,x3,x4]]
     [285] sm1.rrank(@);
     4

     [286]  sm1.gkz([  [[1,1,1,1],[0,1,3,4]],  [1,2]]);
     [[x4*dx4+x3*dx3+x2*dx2+x1*dx1-1,4*x4*dx4+3*x3*dx3+x2*dx2-2,
      -dx1*dx4+dx2*dx3,-dx2^2*dx4+dx1*dx3^2,dx1^2*dx3-dx2^3,-dx2*dx4^2+dx3^3],
      [x1,x2,x3,x4]]
     [287] sm1.rrank(@);
     5

