C PMAT3D    SOURCE    FD218221  24/02/07    21:15:23     11834          
      SUBROUTINE PMAT3D(A,B,C,N)
      IMPLICIT INTEGER(I-N)
      IMPLICIT REAL*8 (A-H,O-Z)
      
c     produit matrices carrees
      integer n
      real*8 A(N,N),B(N,N),C(N,N)
      integer i,j,k

      do i=1,n
        do j=1,n
            c(i,j)=0.d0
            do k=1,n
                c(i,j)=c(i,j)+a(i,k)*b(k,j)
            end do
        end do
      end do
      return
      end