rrank

 a rrank b
 array a;  number b
It computes the holonomic rank for regular holonomic system.
For the algorithm, see Grobner deformations of hypergeometric differential equations, 1999, Springer.
Chapter 2.
Example 1 : 
 [ [( (x Dx)^2 + ( y Dy)^2) ( x Dx y Dy -1)] (x,y)] rrank ::



Nobuki Takayama 2020-11-24