          SUBROUTINE ZTPTRS( UPLO, TRANS, DIAG, N, NRHS, AP, B, LDB, INFO )
    *
    *  -- LAPACK routine (version 3.1) --
    *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
    *     November 2006
    *
    *     .. Scalar Arguments ..
          CHARACTER          DIAG, TRANS, UPLO
          INTEGER            INFO, LDB, N, NRHS
    *     ..
    *     .. Array Arguments ..
          COMPLEX*16         AP( * ), B( LDB, * )
    *     ..
    *
    *  Purpose
    *  =======
    *
    *  ZTPTRS solves a triangular system of the form
    *
    *     A * X = B,  A**T * X = B,  or  A**H * X = B,
    *
    *  where A is a triangular matrix of order N stored in packed format,
    *  and B is an N-by-NRHS matrix.  A check is made to verify that A is
    *  nonsingular.
    *
    *  Arguments
    *  =========
    *
    *  UPLO    (input) CHARACTER*1
    *          = 'U':  A is upper triangular;
    *          = 'L':  A is lower triangular.
    *
    *  TRANS   (input) CHARACTER*1
    *          Specifies the form of the system of equations:
    *          = 'N':  A * X = B     (No transpose)
    *          = 'T':  A**T * X = B  (Transpose)
    *          = 'C':  A**H * X = B  (Conjugate transpose)
    *
    *  DIAG    (input) CHARACTER*1
    *          = 'N':  A is non-unit triangular;
    *          = 'U':  A is unit triangular.
    *
    *  N       (input) INTEGER
    *          The order of the matrix A.  N >= 0.
    *
    *  NRHS    (input) INTEGER
    *          The number of right hand sides, i.e., the number of columns
    *          of the matrix B.  NRHS >= 0.
    *
    *  AP      (input) COMPLEX*16 array, dimension (N*(N+1)/2)
    *          The upper or lower triangular matrix A, packed columnwise in
    *          a linear array.  The j-th column of A is stored in the array
    *          AP as follows:
    *          if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j;
    *          if UPLO = 'L', AP(i + (j-1)*(2*n-j)/2) = A(i,j) for j<=i<=n.
    *
    *  B       (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
    *          On entry, the right hand side matrix B.
    *          On exit, if INFO = 0, the solution matrix X.
    *
    *  LDB     (input) INTEGER
    *          The leading dimension of the array B.  LDB >= max(1,N).
    *
    *  INFO    (output) INTEGER
    *          = 0:  successful exit
    *          < 0:  if INFO = -i, the i-th argument had an illegal value
    *          > 0:  if INFO = i, the i-th diagonal element of A is zero,
    *                indicating that the matrix is singular and the
    *                solutions X have not been computed.
    *
    *  =====================================================================
    *
    *     .. Parameters ..
          COMPLEX*16         ZERO
          PARAMETER          ( ZERO = ( 0.0D+0, 0.0D+0 ) )
    *     ..
    *     .. Local Scalars ..
          LOGICAL            NOUNIT, UPPER
          INTEGER            J, JC
    *     ..
    *     .. External Functions ..
          LOGICAL            LSAME
          EXTERNAL           LSAME
    *     ..
    *     .. External Subroutines ..
          EXTERNAL           XERBLA, ZTPSV
    *     ..
    *     .. Intrinsic Functions ..
          INTRINSIC          MAX
    *     ..
    *     .. Executable Statements ..
    *
    *     Test the input parameters.
    *
          INFO = 0
          UPPER = LSAME( UPLO, 'U' )
          NOUNIT = LSAME( DIAG, 'N' )
          IF( .NOT.UPPER .AND. .NOT.LSAME( UPLO, 'L' ) ) THEN
             INFO = -1
          ELSE IF( .NOT.LSAME( TRANS, 'N' ) .AND. .NOT.
         $         LSAME( TRANS, 'T' ) .AND. .NOT.LSAME( TRANS, 'C' ) ) THEN
             INFO = -2
          ELSE IF( .NOT.NOUNIT .AND. .NOT.LSAME( DIAG, 'U' ) ) THEN
             INFO = -3
          ELSE IF( N.LT.0 ) THEN
             INFO = -4
          ELSE IF( NRHS.LT.0 ) THEN
             INFO = -5
          ELSE IF( LDB.LT.MAX( 1, N ) ) THEN
             INFO = -8
          END IF
          IF( INFO.NE.0 ) THEN
             CALL XERBLA( 'ZTPTRS', -INFO )
             RETURN
          END IF
    *
    *     Quick return if possible
    *
          IF( N.EQ.0 )
         $   RETURN
    *
    *     Check for singularity.
    *
          IF( NOUNIT ) THEN
             IF( UPPER ) THEN
                JC = 1
                DO 10 INFO = 1, N
                   IF( AP( JC+INFO-1 ).EQ.ZERO )
         $            RETURN
                   JC = JC + INFO
       10       CONTINUE
             ELSE
                JC = 1
                DO 20 INFO = 1, N
                   IF( AP( JC ).EQ.ZERO )
         $            RETURN
                   JC = JC + N - INFO + 1
       20       CONTINUE
             END IF
          END IF
          INFO = 0
    *
    *     Solve  A * x = b,  A**T * x = b,  or  A**H * x = b.
    *
          DO 30 J = 1, NRHS
             CALL ZTPSV( UPLO, TRANS, DIAG, N, AP, B( 1, J ), 1 )
       30 CONTINUE
    *
          RETURN
    *
    *     End of ZTPTRS
    *
          END