C
      SUBROUTINE CHOLSK (IDA, NMAT, M, N, A, NRHS, IDB, B)
C
C   CHOLESKY DECOMPOSITION/SUBSTITUTION SUBROUTINE.
C
C   11/28/84  D H BAILEY  MODIFIED FOR NAS KERNEL TEST
C
      REAL A(-M:0, 0:N, 0:IDA), B(0:N, 0:NRHS, 0:IDB), EPSS(0:256)
      DATA EPS/1E-13/
C
C  CHOLESKY DECOMPOSITION
C
      DO L = 0, NMAT
      DO 1 J = 0, N
        I0 = MAX ( -M, -J )
C
C  OFF DIAGONAL ELEMENTS
C
        DO 2 I = I0, -1
          DO 3 JJ = I0 - I, -1
3             A(I,J,L) = A(I,J,L) - A(JJ,I+J,L) * A(I+JJ,J,L)
2           A(I,J,L) = A(I,J,L) * A(0,I+J,L)
C
C  STORE INVERSE OF DIAGONAL ELEMENTS
C
4         EPSS(L) = EPS * A(0,J,L)
        DO 5 JJ = I0, -1
5           A(0,J,L) = A(0,J,L) - A(JJ,J,L) ** 2
1         A(0,J,L) = 1. / SQRT ( ABS (EPSS(L) + A(0,J,L)) )
C
C  SOLUTION
C
      DO 6 I = 0, NRHS
        DO 7 K = 0, N
8           B(K,I,L) = B(K,I,L) * A(0,K,L)
          DO 7 JJ = 1, MIN (M, N-K)
7             B(K+JJ,I,L) = B(K+JJ,I,L) -  A(-JJ,K+JJ,L) * B(K,I,L)
C
        DO 6 K = N, 0, -1
9           B(K,I,L) = B(K,I,L) * A(0,K,L)
          DO 6 JJ = 1, MIN (M, K)
6             B(K-JJ,I,L) = B(K-JJ,I,L) - A(-JJ,K,L) * B(K,I,L)
      ENDDO
C
      RETURN
      END