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313 lines
7.9 KiB
313 lines
7.9 KiB
/* dsymv.f -- translated by f2c (version 20061008). |
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You must link the resulting object file with libf2c: |
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on Microsoft Windows system, link with libf2c.lib; |
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm |
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or, if you install libf2c.a in a standard place, with -lf2c -lm |
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-- in that order, at the end of the command line, as in |
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cc *.o -lf2c -lm |
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g., |
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http://www.netlib.org/f2c/libf2c.zip |
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*/ |
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#include "clapack.h" |
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/* Subroutine */ int dsymv_(char *uplo, integer *n, doublereal *alpha, |
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doublereal *a, integer *lda, doublereal *x, integer *incx, doublereal |
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*beta, doublereal *y, integer *incy) |
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{ |
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/* System generated locals */ |
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integer a_dim1, a_offset, i__1, i__2; |
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/* Local variables */ |
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integer i__, j, ix, iy, jx, jy, kx, ky, info; |
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doublereal temp1, temp2; |
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extern logical lsame_(char *, char *); |
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extern /* Subroutine */ int xerbla_(char *, integer *); |
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/* .. Scalar Arguments .. */ |
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/* .. */ |
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/* .. Array Arguments .. */ |
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/* .. */ |
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/* Purpose */ |
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/* ======= */ |
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/* DSYMV performs the matrix-vector operation */ |
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/* y := alpha*A*x + beta*y, */ |
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/* where alpha and beta are scalars, x and y are n element vectors and */ |
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/* A is an n by n symmetric matrix. */ |
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/* Arguments */ |
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/* ========== */ |
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/* UPLO - CHARACTER*1. */ |
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/* On entry, UPLO specifies whether the upper or lower */ |
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/* triangular part of the array A is to be referenced as */ |
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/* follows: */ |
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/* UPLO = 'U' or 'u' Only the upper triangular part of A */ |
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/* is to be referenced. */ |
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/* UPLO = 'L' or 'l' Only the lower triangular part of A */ |
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/* is to be referenced. */ |
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/* Unchanged on exit. */ |
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/* N - INTEGER. */ |
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/* On entry, N specifies the order of the matrix A. */ |
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/* N must be at least zero. */ |
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/* Unchanged on exit. */ |
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/* ALPHA - DOUBLE PRECISION. */ |
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/* On entry, ALPHA specifies the scalar alpha. */ |
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/* Unchanged on exit. */ |
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/* A - DOUBLE PRECISION array of DIMENSION ( LDA, n ). */ |
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/* Before entry with UPLO = 'U' or 'u', the leading n by n */ |
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/* upper triangular part of the array A must contain the upper */ |
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/* triangular part of the symmetric matrix and the strictly */ |
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/* lower triangular part of A is not referenced. */ |
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/* Before entry with UPLO = 'L' or 'l', the leading n by n */ |
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/* lower triangular part of the array A must contain the lower */ |
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/* triangular part of the symmetric matrix and the strictly */ |
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/* upper triangular part of A is not referenced. */ |
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/* Unchanged on exit. */ |
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/* LDA - INTEGER. */ |
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/* On entry, LDA specifies the first dimension of A as declared */ |
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/* in the calling (sub) program. LDA must be at least */ |
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/* max( 1, n ). */ |
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/* Unchanged on exit. */ |
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/* X - DOUBLE PRECISION array of dimension at least */ |
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/* ( 1 + ( n - 1 )*abs( INCX ) ). */ |
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/* Before entry, the incremented array X must contain the n */ |
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/* element vector x. */ |
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/* Unchanged on exit. */ |
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/* INCX - INTEGER. */ |
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/* On entry, INCX specifies the increment for the elements of */ |
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/* X. INCX must not be zero. */ |
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/* Unchanged on exit. */ |
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/* BETA - DOUBLE PRECISION. */ |
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/* On entry, BETA specifies the scalar beta. When BETA is */ |
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/* supplied as zero then Y need not be set on input. */ |
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/* Unchanged on exit. */ |
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/* Y - DOUBLE PRECISION array of dimension at least */ |
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/* ( 1 + ( n - 1 )*abs( INCY ) ). */ |
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/* Before entry, the incremented array Y must contain the n */ |
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/* element vector y. On exit, Y is overwritten by the updated */ |
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/* vector y. */ |
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/* INCY - INTEGER. */ |
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/* On entry, INCY specifies the increment for the elements of */ |
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/* Y. INCY must not be zero. */ |
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/* Unchanged on exit. */ |
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/* Level 2 Blas routine. */ |
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/* -- Written on 22-October-1986. */ |
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/* Jack Dongarra, Argonne National Lab. */ |
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/* Jeremy Du Croz, Nag Central Office. */ |
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/* Sven Hammarling, Nag Central Office. */ |
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/* Richard Hanson, Sandia National Labs. */ |
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/* .. Parameters .. */ |
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/* .. */ |
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/* .. Local Scalars .. */ |
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/* .. */ |
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/* .. External Functions .. */ |
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/* .. */ |
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/* .. External Subroutines .. */ |
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/* .. */ |
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/* .. Intrinsic Functions .. */ |
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/* .. */ |
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/* Test the input parameters. */ |
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/* Parameter adjustments */ |
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a_dim1 = *lda; |
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a_offset = 1 + a_dim1; |
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a -= a_offset; |
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--x; |
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--y; |
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/* Function Body */ |
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info = 0; |
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if (! lsame_(uplo, "U") && ! lsame_(uplo, "L")) { |
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info = 1; |
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} else if (*n < 0) { |
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info = 2; |
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} else if (*lda < max(1,*n)) { |
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info = 5; |
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} else if (*incx == 0) { |
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info = 7; |
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} else if (*incy == 0) { |
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info = 10; |
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} |
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if (info != 0) { |
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xerbla_("DSYMV ", &info); |
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return 0; |
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} |
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/* Quick return if possible. */ |
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if (*n == 0 || *alpha == 0. && *beta == 1.) { |
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return 0; |
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} |
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/* Set up the start points in X and Y. */ |
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if (*incx > 0) { |
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kx = 1; |
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} else { |
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kx = 1 - (*n - 1) * *incx; |
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} |
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if (*incy > 0) { |
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ky = 1; |
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} else { |
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ky = 1 - (*n - 1) * *incy; |
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} |
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/* Start the operations. In this version the elements of A are */ |
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/* accessed sequentially with one pass through the triangular part */ |
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/* of A. */ |
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/* First form y := beta*y. */ |
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if (*beta != 1.) { |
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if (*incy == 1) { |
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if (*beta == 0.) { |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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y[i__] = 0.; |
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/* L10: */ |
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} |
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} else { |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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y[i__] = *beta * y[i__]; |
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/* L20: */ |
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} |
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} |
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} else { |
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iy = ky; |
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if (*beta == 0.) { |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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y[iy] = 0.; |
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iy += *incy; |
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/* L30: */ |
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} |
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} else { |
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i__1 = *n; |
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for (i__ = 1; i__ <= i__1; ++i__) { |
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y[iy] = *beta * y[iy]; |
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iy += *incy; |
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/* L40: */ |
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} |
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} |
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} |
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} |
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if (*alpha == 0.) { |
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return 0; |
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} |
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if (lsame_(uplo, "U")) { |
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/* Form y when A is stored in upper triangle. */ |
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if (*incx == 1 && *incy == 1) { |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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temp1 = *alpha * x[j]; |
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temp2 = 0.; |
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i__2 = j - 1; |
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for (i__ = 1; i__ <= i__2; ++i__) { |
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y[i__] += temp1 * a[i__ + j * a_dim1]; |
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temp2 += a[i__ + j * a_dim1] * x[i__]; |
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/* L50: */ |
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} |
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y[j] = y[j] + temp1 * a[j + j * a_dim1] + *alpha * temp2; |
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/* L60: */ |
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} |
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} else { |
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jx = kx; |
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jy = ky; |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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temp1 = *alpha * x[jx]; |
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temp2 = 0.; |
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ix = kx; |
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iy = ky; |
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i__2 = j - 1; |
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for (i__ = 1; i__ <= i__2; ++i__) { |
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y[iy] += temp1 * a[i__ + j * a_dim1]; |
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temp2 += a[i__ + j * a_dim1] * x[ix]; |
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ix += *incx; |
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iy += *incy; |
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/* L70: */ |
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} |
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y[jy] = y[jy] + temp1 * a[j + j * a_dim1] + *alpha * temp2; |
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jx += *incx; |
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jy += *incy; |
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/* L80: */ |
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} |
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} |
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} else { |
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/* Form y when A is stored in lower triangle. */ |
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if (*incx == 1 && *incy == 1) { |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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temp1 = *alpha * x[j]; |
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temp2 = 0.; |
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y[j] += temp1 * a[j + j * a_dim1]; |
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i__2 = *n; |
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for (i__ = j + 1; i__ <= i__2; ++i__) { |
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y[i__] += temp1 * a[i__ + j * a_dim1]; |
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temp2 += a[i__ + j * a_dim1] * x[i__]; |
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/* L90: */ |
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} |
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y[j] += *alpha * temp2; |
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/* L100: */ |
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} |
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} else { |
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jx = kx; |
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jy = ky; |
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i__1 = *n; |
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for (j = 1; j <= i__1; ++j) { |
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temp1 = *alpha * x[jx]; |
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temp2 = 0.; |
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y[jy] += temp1 * a[j + j * a_dim1]; |
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ix = jx; |
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iy = jy; |
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i__2 = *n; |
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for (i__ = j + 1; i__ <= i__2; ++i__) { |
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ix += *incx; |
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iy += *incy; |
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y[iy] += temp1 * a[i__ + j * a_dim1]; |
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temp2 += a[i__ + j * a_dim1] * x[ix]; |
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/* L110: */ |
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} |
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y[jy] += *alpha * temp2; |
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jx += *incx; |
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jy += *incy; |
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/* L120: */ |
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} |
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} |
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} |
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return 0; |
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/* End of DSYMV . */ |
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} /* dsymv_ */
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