zhemv.c

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/* zhemv.f -- translated by f2c (version 20061008).
   You must link the resulting object file with libf2c:
        on Microsoft Windows system, link with libf2c.lib;
        on Linux or Unix systems, link with .../path/to/libf2c.a -lm
        or, if you install libf2c.a in a standard place, with -lf2c -lm
        -- in that order, at the end of the command line, as in
                cc *.o -lf2c -lm
        Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,

                http://www.netlib.org/f2c/libf2c.zip
*/

#include "f2c.h"
#include "blaswrap.h"

/* Subroutine */ int zhemv_(char *uplo, integer *n, doublecomplex *alpha, 
        doublecomplex *a, integer *lda, doublecomplex *x, integer *incx, 
        doublecomplex *beta, doublecomplex *y, integer *incy)
{
    /* System generated locals */
    integer a_dim1, a_offset, i__1, i__2, i__3, i__4, i__5;
    doublereal d__1;
    doublecomplex z__1, z__2, z__3, z__4;

    /* Builtin functions */
    void d_cnjg(doublecomplex *, doublecomplex *);

    /* Local variables */
    integer i__, j, ix, iy, jx, jy, kx, ky, info;
    doublecomplex temp1, temp2;
    extern logical lsame_(char *, char *);
    extern /* Subroutine */ int xerbla_(char *, integer *);

/*     .. Scalar Arguments .. */
/*     .. */
/*     .. Array Arguments .. */
/*     .. */

/*  Purpose */
/*  ======= */

/*  ZHEMV  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. */

/*  Arguments */
/*  ========== */

/*  UPLO   - CHARACTER*1. */
/*           On entry, UPLO specifies whether the upper or lower */
/*           triangular part of the array A is to be referenced as */
/*           follows: */

/*              UPLO = 'U' or 'u'   Only the upper triangular part of A */
/*                                  is to be referenced. */

/*              UPLO = 'L' or 'l'   Only the lower triangular part of A */
/*                                  is to be referenced. */

/*           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*16      . */
/*           On entry, ALPHA specifies the scalar alpha. */
/*           Unchanged on exit. */

/*  A      - COMPLEX*16       array of DIMENSION ( LDA, n ). */
/*           Before entry with  UPLO = 'U' or 'u', the leading n by n */
/*           upper triangular part of the array A must contain the upper */
/*           triangular part of the hermitian matrix and the strictly */
/*           lower triangular part of A is not referenced. */
/*           Before entry with UPLO = 'L' or 'l', the leading n by n */
/*           lower triangular part of the array A must contain the lower */
/*           triangular part of the hermitian matrix and the strictly */
/*           upper triangular part of A is not referenced. */
/*           Note that the imaginary parts of the diagonal elements need */
/*           not be set and are assumed to be zero. */
/*           Unchanged on exit. */

/*  LDA    - INTEGER. */
/*           On entry, LDA specifies the first dimension of A as declared */
/*           in the calling (sub) program. LDA must be at least */
/*           max( 1, n ). */
/*           Unchanged on exit. */

/*  X      - COMPLEX*16       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*16      . */
/*           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*16       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. */


/*  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 .. */
/*     .. */
/*     .. Local Scalars .. */
/*     .. */
/*     .. External Functions .. */
/*     .. */
/*     .. External Subroutines .. */
/*     .. */
/*     .. Intrinsic Functions .. */
/*     .. */

/*     Test the input parameters. */

    /* Parameter adjustments */
    a_dim1 = *lda;
    a_offset = 1 + a_dim1;
    a -= a_offset;
    --x;
    --y;

    /* Function Body */
    info = 0;
    if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) {
        info = 1;
    } else if (*n < 0) {
        info = 2;
    } else if (*lda < max(1,*n)) {
        info = 5;
    } else if (*incx == 0) {
        info = 7;
    } else if (*incy == 0) {
        info = 10;
    }
    if (info != 0) {
        xerbla_("ZHEMV ", &info);
        return 0;
    }

/*     Quick return if possible. */

    if (*n == 0 || alpha->r == 0. && alpha->i == 0. && (beta->r == 1. && 
            beta->i == 0.)) {
        return 0;
    }

/*     Set up the start points in  X  and  Y. */

    if (*incx > 0) {
        kx = 1;
    } else {
        kx = 1 - (*n - 1) * *incx;
    }
    if (*incy > 0) {
        ky = 1;
    } else {
        ky = 1 - (*n - 1) * *incy;
    }

/*     Start the operations. In this version the elements of A are */
/*     accessed sequentially with one pass through the triangular part */
/*     of A. */

/*     First form  y := beta*y. */

    if (beta->r != 1. || beta->i != 0.) {
        if (*incy == 1) {
            if (beta->r == 0. && beta->i == 0.) {
                i__1 = *n;
                for (i__ = 1; i__ <= i__1; ++i__) {
                    i__2 = i__;
                    y[i__2].r = 0., y[i__2].i = 0.;
/* L10: */
                }
            } else {
                i__1 = *n;
                for (i__ = 1; i__ <= i__1; ++i__) {
                    i__2 = i__;
                    i__3 = i__;
                    z__1.r = beta->r * y[i__3].r - beta->i * y[i__3].i, 
                            z__1.i = beta->r * y[i__3].i + beta->i * y[i__3]
                            .r;
                    y[i__2].r = z__1.r, y[i__2].i = z__1.i;
/* L20: */
                }
            }
        } else {
            iy = ky;
            if (beta->r == 0. && beta->i == 0.) {
                i__1 = *n;
                for (i__ = 1; i__ <= i__1; ++i__) {
                    i__2 = iy;
                    y[i__2].r = 0., y[i__2].i = 0.;
                    iy += *incy;
/* L30: */
                }
            } else {
                i__1 = *n;
                for (i__ = 1; i__ <= i__1; ++i__) {
                    i__2 = iy;
                    i__3 = iy;
                    z__1.r = beta->r * y[i__3].r - beta->i * y[i__3].i, 
                            z__1.i = beta->r * y[i__3].i + beta->i * y[i__3]
                            .r;
                    y[i__2].r = z__1.r, y[i__2].i = z__1.i;
                    iy += *incy;
/* L40: */
                }
            }
        }
    }
    if (alpha->r == 0. && alpha->i == 0.) {
        return 0;
    }
    if (lsame_(uplo, "U")) {

/*        Form  y  when A is stored in upper triangle. */

        if (*incx == 1 && *incy == 1) {
            i__1 = *n;
            for (j = 1; j <= i__1; ++j) {
                i__2 = j;
                z__1.r = alpha->r * x[i__2].r - alpha->i * x[i__2].i, z__1.i =
                         alpha->r * x[i__2].i + alpha->i * x[i__2].r;
                temp1.r = z__1.r, temp1.i = z__1.i;
                temp2.r = 0., temp2.i = 0.;
                i__2 = j - 1;
                for (i__ = 1; i__ <= i__2; ++i__) {
                    i__3 = i__;
                    i__4 = i__;
                    i__5 = i__ + j * a_dim1;
                    z__2.r = temp1.r * a[i__5].r - temp1.i * a[i__5].i, 
                            z__2.i = temp1.r * a[i__5].i + temp1.i * a[i__5]
                            .r;
                    z__1.r = y[i__4].r + z__2.r, z__1.i = y[i__4].i + z__2.i;
                    y[i__3].r = z__1.r, y[i__3].i = z__1.i;
                    d_cnjg(&z__3, &a[i__ + j * a_dim1]);
                    i__3 = i__;
                    z__2.r = z__3.r * x[i__3].r - z__3.i * x[i__3].i, z__2.i =
                             z__3.r * x[i__3].i + z__3.i * x[i__3].r;
                    z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
                    temp2.r = z__1.r, temp2.i = z__1.i;
/* L50: */
                }
                i__2 = j;
                i__3 = j;
                i__4 = j + j * a_dim1;
                d__1 = a[i__4].r;
                z__3.r = d__1 * temp1.r, z__3.i = d__1 * temp1.i;
                z__2.r = y[i__3].r + z__3.r, z__2.i = y[i__3].i + z__3.i;
                z__4.r = alpha->r * temp2.r - alpha->i * temp2.i, z__4.i = 
                        alpha->r * temp2.i + alpha->i * temp2.r;
                z__1.r = z__2.r + z__4.r, z__1.i = z__2.i + z__4.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
/* L60: */
            }
        } else {
            jx = kx;
            jy = ky;
            i__1 = *n;
            for (j = 1; j <= i__1; ++j) {
                i__2 = jx;
                z__1.r = alpha->r * x[i__2].r - alpha->i * x[i__2].i, z__1.i =
                         alpha->r * x[i__2].i + alpha->i * x[i__2].r;
                temp1.r = z__1.r, temp1.i = z__1.i;
                temp2.r = 0., temp2.i = 0.;
                ix = kx;
                iy = ky;
                i__2 = j - 1;
                for (i__ = 1; i__ <= i__2; ++i__) {
                    i__3 = iy;
                    i__4 = iy;
                    i__5 = i__ + j * a_dim1;
                    z__2.r = temp1.r * a[i__5].r - temp1.i * a[i__5].i, 
                            z__2.i = temp1.r * a[i__5].i + temp1.i * a[i__5]
                            .r;
                    z__1.r = y[i__4].r + z__2.r, z__1.i = y[i__4].i + z__2.i;
                    y[i__3].r = z__1.r, y[i__3].i = z__1.i;
                    d_cnjg(&z__3, &a[i__ + j * a_dim1]);
                    i__3 = ix;
                    z__2.r = z__3.r * x[i__3].r - z__3.i * x[i__3].i, z__2.i =
                             z__3.r * x[i__3].i + z__3.i * x[i__3].r;
                    z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
                    temp2.r = z__1.r, temp2.i = z__1.i;
                    ix += *incx;
                    iy += *incy;
/* L70: */
                }
                i__2 = jy;
                i__3 = jy;
                i__4 = j + j * a_dim1;
                d__1 = a[i__4].r;
                z__3.r = d__1 * temp1.r, z__3.i = d__1 * temp1.i;
                z__2.r = y[i__3].r + z__3.r, z__2.i = y[i__3].i + z__3.i;
                z__4.r = alpha->r * temp2.r - alpha->i * temp2.i, z__4.i = 
                        alpha->r * temp2.i + alpha->i * temp2.r;
                z__1.r = z__2.r + z__4.r, z__1.i = z__2.i + z__4.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
                jx += *incx;
                jy += *incy;
/* L80: */
            }
        }
    } else {

/*        Form  y  when A is stored in lower triangle. */

        if (*incx == 1 && *incy == 1) {
            i__1 = *n;
            for (j = 1; j <= i__1; ++j) {
                i__2 = j;
                z__1.r = alpha->r * x[i__2].r - alpha->i * x[i__2].i, z__1.i =
                         alpha->r * x[i__2].i + alpha->i * x[i__2].r;
                temp1.r = z__1.r, temp1.i = z__1.i;
                temp2.r = 0., temp2.i = 0.;
                i__2 = j;
                i__3 = j;
                i__4 = j + j * a_dim1;
                d__1 = a[i__4].r;
                z__2.r = d__1 * temp1.r, z__2.i = d__1 * temp1.i;
                z__1.r = y[i__3].r + z__2.r, z__1.i = y[i__3].i + z__2.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
                i__2 = *n;
                for (i__ = j + 1; i__ <= i__2; ++i__) {
                    i__3 = i__;
                    i__4 = i__;
                    i__5 = i__ + j * a_dim1;
                    z__2.r = temp1.r * a[i__5].r - temp1.i * a[i__5].i, 
                            z__2.i = temp1.r * a[i__5].i + temp1.i * a[i__5]
                            .r;
                    z__1.r = y[i__4].r + z__2.r, z__1.i = y[i__4].i + z__2.i;
                    y[i__3].r = z__1.r, y[i__3].i = z__1.i;
                    d_cnjg(&z__3, &a[i__ + j * a_dim1]);
                    i__3 = i__;
                    z__2.r = z__3.r * x[i__3].r - z__3.i * x[i__3].i, z__2.i =
                             z__3.r * x[i__3].i + z__3.i * x[i__3].r;
                    z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
                    temp2.r = z__1.r, temp2.i = z__1.i;
/* L90: */
                }
                i__2 = j;
                i__3 = j;
                z__2.r = alpha->r * temp2.r - alpha->i * temp2.i, z__2.i = 
                        alpha->r * temp2.i + alpha->i * temp2.r;
                z__1.r = y[i__3].r + z__2.r, z__1.i = y[i__3].i + z__2.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
/* L100: */
            }
        } else {
            jx = kx;
            jy = ky;
            i__1 = *n;
            for (j = 1; j <= i__1; ++j) {
                i__2 = jx;
                z__1.r = alpha->r * x[i__2].r - alpha->i * x[i__2].i, z__1.i =
                         alpha->r * x[i__2].i + alpha->i * x[i__2].r;
                temp1.r = z__1.r, temp1.i = z__1.i;
                temp2.r = 0., temp2.i = 0.;
                i__2 = jy;
                i__3 = jy;
                i__4 = j + j * a_dim1;
                d__1 = a[i__4].r;
                z__2.r = d__1 * temp1.r, z__2.i = d__1 * temp1.i;
                z__1.r = y[i__3].r + z__2.r, z__1.i = y[i__3].i + z__2.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
                ix = jx;
                iy = jy;
                i__2 = *n;
                for (i__ = j + 1; i__ <= i__2; ++i__) {
                    ix += *incx;
                    iy += *incy;
                    i__3 = iy;
                    i__4 = iy;
                    i__5 = i__ + j * a_dim1;
                    z__2.r = temp1.r * a[i__5].r - temp1.i * a[i__5].i, 
                            z__2.i = temp1.r * a[i__5].i + temp1.i * a[i__5]
                            .r;
                    z__1.r = y[i__4].r + z__2.r, z__1.i = y[i__4].i + z__2.i;
                    y[i__3].r = z__1.r, y[i__3].i = z__1.i;
                    d_cnjg(&z__3, &a[i__ + j * a_dim1]);
                    i__3 = ix;
                    z__2.r = z__3.r * x[i__3].r - z__3.i * x[i__3].i, z__2.i =
                             z__3.r * x[i__3].i + z__3.i * x[i__3].r;
                    z__1.r = temp2.r + z__2.r, z__1.i = temp2.i + z__2.i;
                    temp2.r = z__1.r, temp2.i = z__1.i;
/* L110: */
                }
                i__2 = jy;
                i__3 = jy;
                z__2.r = alpha->r * temp2.r - alpha->i * temp2.i, z__2.i = 
                        alpha->r * temp2.i + alpha->i * temp2.r;
                z__1.r = y[i__3].r + z__2.r, z__1.i = y[i__3].i + z__2.i;
                y[i__2].r = z__1.r, y[i__2].i = z__1.i;
                jx += *incx;
                jy += *incy;
/* L120: */
            }
        }
    }

    return 0;

/*     End of ZHEMV . */

} /* zhemv_ */