SUBROUTINE UXTAXF(N,M,X,LDX,A,LDA,B,LDB)
C  This routine forms the matrix product  B = X'AX, A being symmetric.
C  Inputs:
C  N            Row dimension of X and order of A
C  M            Column dimension of X and order of B
C  X            X matrix
C  LDX          Leading dimension of X in calling program
C  A            A matrix (full storeage)
C  LDA          Leading dimension of A in calling program
C  LDB          Leading dimension of B in calling program
C  Outputs:
C  B            B matrix, B = X'AX
      IMPLICIT REAL*8 (A-H,O-Z)
      DIMENSION X(LDX,M),A(LDA,N),B(LDB,M)
      DO 20 I=1,M
      DO 20 J=1,I
      AA=0.0D0
      DO 10 K=1,N
      DO 10 L=1,N
   10 AA=AA+X(K,I)*A(K,L)*X(L,J)
      B(I,J)=AA
   20 B(J,I)=AA
      RETURN
      END