Function: sumnum
Section: sums
C-Name: sumnum0
Prototype: V=GGEDGD0,L,p
Help: sumnum(X=a,sig,expr,{tab},{flag=0}): numerical summation of expr from 
 X = ceiling(a) to +infinity. sig is either a scalar or a two-component vector
 coding the function's decrease rate at infinity. It is assumed that the
 scalar part of sig is to the right of all poles of expr. If present, tab
 must be initialized by sumnuminit. If flag is nonzero, assumes that
 conj(expr(z)) = expr(conj(z)).

