text:       SUBROUTINE CHPMV(UPLO,N,ALPHA,AP,X,INCX,BETA,Y,INCY)
  *     .. Scalar Arguments ..
        COMPLEX ALPHA,BETA
        INTEGER INCX,INCY,N
        CHARACTER UPLO
  *     ..
  *     .. Array Arguments ..
        COMPLEX AP(*),X(*),Y(*)
  *     ..
  *
  *  Purpose
  *  =======
  *
  *  CHPMV  performs the matrix-vector operation
  *
  *     y := alpha*A*x + beta*y,
  *
  *  where alpha and beta are scalars, x and y are n element vectors and
  *  A is an n by n hermitian matrix, supplied in packed form.
  *
  *  Arguments
  *  ==========
  *
  *  UPLO   - CHARACTER*1.
  *           On entry, UPLO specifies whether the upper or lower
  *           triangular part of the matrix A is supplied in the packed
  *           array AP as follows:
  *
  *              UPLO = 'U' or 'u'   The upper triangular part of A is
  *                                  supplied in AP.
  *
  *              UPLO = 'L' or 'l'   The lower triangular part of A is
  *                                  supplied in AP.
  *
  *           Unchanged on exit.
  *
  *  N      - INTEGER.
  *           On entry, N specifies the order of the matrix A.
  *           N must be at least zero.
  *           Unchanged on exit.
  *
  *  ALPHA  - COMPLEX         .
  *           On entry, ALPHA specifies the scalar alpha.
  *           Unchanged on exit.
  *
  *  AP     - COMPLEX          array of DIMENSION at least
  *           ( ( n*( n + 1 ) )/2 ).
  *           Before entry with UPLO = 'U' or 'u', the array AP must
  *           contain the upper triangular part of the hermitian matrix
  *           packed sequentially, column by column, so that AP( 1 )
  *           contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 )
  *           and a( 2, 2 ) respectively, and so on.
  *           Before entry with UPLO = 'L' or 'l', the array AP must
  *           contain the lower triangular part of the hermitian matrix
  *           packed sequentially, column by column, so that AP( 1 )
  *           contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 )
  *           and a( 3, 1 ) respectively, and so on.
  *           Note that the imaginary parts of the diagonal elements need
  *           not be set and are assumed to be zero.
  *           Unchanged on exit.
  *
  *  X      - COMPLEX          array of dimension at least
  *           ( 1 + ( n - 1 )*abs( INCX ) ).
  *           Before entry, the incremented array X must contain the n
  *           element vector x.
  *           Unchanged on exit.
  *
  *  INCX   - INTEGER.
  *           On entry, INCX specifies the increment for the elements of
  *           X. INCX must not be zero.
  *           Unchanged on exit.
  *
  *  BETA   - COMPLEX         .
  *           On entry, BETA specifies the scalar beta. When BETA is
  *           supplied as zero then Y need not be set on input.
  *           Unchanged on exit.
  *
  *  Y      - COMPLEX          array of dimension at least
  *           ( 1 + ( n - 1 )*abs( INCY ) ).
  *           Before entry, the incremented array Y must contain the n
  *           element vector y. On exit, Y is overwritten by the updated
  *           vector y.
  *
  *  INCY   - INTEGER.
  *           On entry, INCY specifies the increment for the elements of
  *           Y. INCY must not be zero.
  *           Unchanged on exit.
  *
  *  Further Details
  *  ===============
  *
  *  Level 2 Blas routine.
  *
  *  -- Written on 22-October-1986.
  *     Jack Dongarra, Argonne National Lab.
  *     Jeremy Du Croz, Nag Central Office.
  *     Sven Hammarling, Nag Central Office.
  *     Richard Hanson, Sandia National Labs.
  *
  *  =====================================================================
  *
  *     .. Parameters ..
        COMPLEX ONE
        PARAMETER (ONE= (1.0E+0,0.0E+0))
        COMPLEX ZERO
        PARAMETER (ZERO= (0.0E+0,0.0E+0))
  *     ..
  *     .. Local Scalars ..
        COMPLEX TEMP1,TEMP2
        INTEGER I,INFO,IX,IY,J,JX,JY,K,KK,KX,KY
  *     ..
  *     .. External Functions ..
        LOGICAL LSAME
        EXTERNAL LSAME
  *     ..
  *     .. External Subroutines ..
        EXTERNAL XERBLA
  *     ..
  *     .. Intrinsic Functions ..
        INTRINSIC CONJG,REAL
  *     ..
  *
  *     Test the input parameters.
  *
        INFO = 0
        IF (.NOT.LSAME(UPLO,'U') .AND. .NOT.LSAME(UPLO,'L')) THEN
            INFO = 1
        ELSE IF (N.LT.0) THEN
            INFO = 2
        ELSE IF (INCX.EQ.0) THEN
            INFO = 6
        ELSE IF (INCY.EQ.0) THEN
            INFO = 9
        END IF
        IF (INFO.NE.0) THEN
            CALL XERBLA('CHPMV ',INFO)
            RETURN
        END IF
  *
  *     Quick return if possible.
  *
        IF ((N.EQ.0) .OR. ((ALPHA.EQ.ZERO).AND. (BETA.EQ.ONE))) RETURN
  *
  *     Set up the start points in  X  and  Y.
  *
        IF (INCX.GT.0) THEN
            KX = 1
        ELSE
            KX = 1 - (N-1)*INCX
        END IF
        IF (INCY.GT.0) THEN
            KY = 1
        ELSE
            KY = 1 - (N-1)*INCY
        END IF
  *
  *     Start the operations. In this version the elements of the array AP
  *     are accessed sequentially with one pass through AP.
  *
  *     First form  y := beta*y.
  *
        IF (BETA.NE.ONE) THEN
            IF (INCY.EQ.1) THEN
                IF (BETA.EQ.ZERO) THEN
                    DO 10 I = 1,N
                        Y(I) = ZERO
     10             CONTINUE
                ELSE
                    DO 20 I = 1,N
                        Y(I) = BETA*Y(I)
     20             CONTINUE
                END IF
            ELSE
                IY = KY
                IF (BETA.EQ.ZERO) THEN
                    DO 30 I = 1,N
                        Y(IY) = ZERO
                        IY = IY + INCY
     30             CONTINUE
                ELSE
                    DO 40 I = 1,N
                        Y(IY) = BETA*Y(IY)
                        IY = IY + INCY
     40             CONTINUE
                END IF
            END IF
        END IF
        IF (ALPHA.EQ.ZERO) RETURN
        KK = 1
        IF (LSAME(UPLO,'U')) THEN
  *
  *        Form  y  when AP contains the upper triangle.
  *
            IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN
                DO 60 J = 1,N
                    TEMP1 = ALPHA*X(J)
                    TEMP2 = ZERO
                    K = KK
                    DO 50 I = 1,J - 1
                        Y(I) = Y(I) + TEMP1*AP(K)
                        TEMP2 = TEMP2 + CONJG(AP(K))*X(I)
                        K = K + 1
     50             CONTINUE
                    Y(J) = Y(J) + TEMP1*REAL(AP(KK+J-1)) + ALPHA*TEMP2
                    KK = KK + J
     60         CONTINUE
            ELSE
                JX = KX
                JY = KY
                DO 80 J = 1,N
                    TEMP1 = ALPHA*X(JX)
                    TEMP2 = ZERO
                    IX = KX
                    IY = KY
                    DO 70 K = KK,KK + J - 2
                        Y(IY) = Y(IY) + TEMP1*AP(K)
                        TEMP2 = TEMP2 + CONJG(AP(K))*X(IX)
                        IX = IX + INCX
                        IY = IY + INCY
     70             CONTINUE
                    Y(JY) = Y(JY) + TEMP1*REAL(AP(KK+J-1)) + ALPHA*TEMP2
                    JX = JX + INCX
                    JY = JY + INCY
                    KK = KK + J
     80         CONTINUE
            END IF
        ELSE
  *
  *        Form  y  when AP contains the lower triangle.
  *
            IF ((INCX.EQ.1) .AND. (INCY.EQ.1)) THEN
                DO 100 J = 1,N
                    TEMP1 = ALPHA*X(J)
                    TEMP2 = ZERO
                    Y(J) = Y(J) + TEMP1*REAL(AP(KK))
                    K = KK + 1
                    DO 90 I = J + 1,N
                        Y(I) = Y(I) + TEMP1*AP(K)
                        TEMP2 = TEMP2 + CONJG(AP(K))*X(I)
                        K = K + 1
     90             CONTINUE
                    Y(J) = Y(J) + ALPHA*TEMP2
                    KK = KK + (N-J+1)
    100         CONTINUE
            ELSE
                JX = KX
                JY = KY
                DO 120 J = 1,N
                    TEMP1 = ALPHA*X(JX)
                    TEMP2 = ZERO
                    Y(JY) = Y(JY) + TEMP1*REAL(AP(KK))
                    IX = JX
                    IY = JY
                    DO 110 K = KK + 1,KK + N - J
                        IX = IX + INCX
                        IY = IY + INCY
                        Y(IY) = Y(IY) + TEMP1*AP(K)
                        TEMP2 = TEMP2 + CONJG(AP(K))*X(IX)
    110             CONTINUE
                    Y(JY) = Y(JY) + ALPHA*TEMP2
                    JX = JX + INCX
                    JY = JY + INCY
                    KK = KK + (N-J+1)
    120         CONTINUE
            END IF
        END IF
  *
        RETURN
  *
  *     End of CHPMV .
  *
        END
  