Function: matdetmod
Section: linear_algebra
C-Name: matdetmod
Prototype: GG
Help: matdetmod(x,d): determinant of the matrix x modulo d.
Doc: Given a matrix $x$ with \typ{INT} entries and $d$ an arbitrary positive
 integer, return the determinant of $x$ modulo $d$.

 \bprog
 ? A = [4,2,3; 4,5,6; 7,8,9]

 ? matdetmod(A,27)
 %2 = 9
 @eprog Note that using the generic function \kbd{matdet} on a matrix with
 \typ{INTMOD} entries uses Gaussian reduction and will fail in general when
 the modulus is not prime.
 \bprog
 ? matdet(A * Mod(1,27))
  ***   at top-level: matdet(A*Mod(1,27))
  ***                 ^------------------
  *** matdet: impossible inverse in Fl_inv: Mod(3, 27).
 @eprog
