SUBROUTINE SSYMV( UPLO, N, ALPHA, A, LDA, X, INCX, $ BETA, Y, INCY ) * * -- Automatically Tuned Linear Algebra Software (ATLAS) * (C) Copyright 2000 All Rights Reserved * * -- ATLAS routine -- F77 Interface -- Version 3.2 -- December 25, 2000 * * -- Suggestions, comments, bugs reports should be sent to the follo- * wing e-mail address: atlas@cs.utk.edu * * Author : Antoine P. Petitet * University of Tennessee - Innovative Computing Laboratory * Knoxville TN, 37996-1301, USA. * * --------------------------------------------------------------------- * * -- Copyright notice and Licensing terms: * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions, and the following disclaimer in * the documentation and/or other materials provided with the distri- * bution. * 3. The name of the University, the ATLAS group, or the names of its * contributors may not be used to endorse or promote products deri- * ved from this software without specific written permission. * * -- Disclaimer: * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEO- * RY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (IN- * CLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * --------------------------------------------------------------------- * * .. Scalar Arguments .. CHARACTER*1 UPLO INTEGER INCX, INCY, LDA, N REAL ALPHA, BETA * .. * .. Array Arguments .. REAL A( LDA, * ), X( * ), Y( * ) * .. * * Purpose * ======= * * SSYMV 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 symmetric matrix. * * Arguments * ========= * * UPLO (input) CHARACTER*1 * On entry, UPLO specifies whether the upper or lower triangu- * lar 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 (input) INTEGER * On entry, N specifies the order of the matrix A. N must be at * least zero. Unchanged on exit. * * ALPHA (input) REAL * On entry, ALPHA specifies the scalar alpha. When ALPHA is * supplied as zero then A and X need not be set on input. Un- * changed on exit. * * A (input) REAL array * On entry, A is an array of DIMENSION ( LDA, n ). Before en- * try with UPLO = 'U' or 'u', the leading n by n upper trian- * gular part of the array A must contain the upper triangular * part of the symmetric matrix and the strictly lower triangu- * lar 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 trian- * gular part of the symmetric matrix and the strictly upper * triangular part of A is not referenced. Unchanged on exit. * * LDA (input) 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 (input) REAL array * On entry, X is an incremented array of dimension at least * ( 1 + ( n - 1 ) * abs( INCX ) ). Before entry, the incremen- * ted array X must contain the vector x. Unchanged on exit. * * INCX (input) INTEGER * On entry, INCX specifies the increment for the elements of X. * INCX must not be zero. Unchanged on exit. * * BETA (input) REAL * 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 (input/output) REAL array * On entry, Y is an incremented array of dimension at least * ( 1 + ( n - 1 ) * abs( INCY ) ). Before entry with BETA non- * zero, the incremented array Y must contain the vector y. On * exit, Y is overwritten by the updated vector y. * * INCY (input) INTEGER * On entry, INCY specifies the increment for the elements of Y. * INCY must not be zero. Unchanged on exit. * * Further Details * =============== * * For further information on the Level 1 BLAS specification, see: * * ``A Proposal for Standard Linear Algebra Subprograms'' by R. Hanson, * F. Krogh and C. Lawson, ACM SIGNUM Newsl., 8(16), 1973, * * ``Basic Linear Algebra Subprograms for Fortran Usage'' by C. Lawson, * R. Hanson, D. Kincaid and F. Krogh, ACM Transactions on Mathematical * Software, 5(3) pp 308-323, 1979. * * For further information on the Level 2 BLAS specification, see: * * ``An Extended Set of FORTRAN Basic Linear Algebra Subprograms'' by * J. Dongarra, J. Du Croz, S. Hammarling and R. Hanson, ACM Transac- * tions on Mathematical Software, 14(1) pp 1-17, 1988. * * ``Algorithm 656: An extended Set of Basic Linear Algebra Subprograms: * Model Implementation and Test Programs'' by J. Dongarra, J. Du Croz, * S. Hammarling and R. Hanson, ACM Transactions on Mathematical Soft- * ware, 14(1) pp 18-32, 1988. * * For further information on the Level 3 BLAS specification, see: * * ``A Set of Level 3 Basic Linear Algebra Subprograms'' by J. Dongarra, * J. Du Croz, I. Duff and S. Hammarling, ACM Transactions on Mathemati- * cal Software, 16(1), pp 1-17, 1990. * * ===================================================================== * * .. Parameters .. INTEGER ILOWER, IUPPER PARAMETER ( IUPPER = 121, ILOWER = 122 ) * .. * .. Local Scalars .. INTEGER INFO, IUPLO * .. * .. External Subroutines .. EXTERNAL ATL_F77WRAP_SSYMV, XERBLA * .. * .. External Functions .. EXTERNAL LSAME LOGICAL LSAME * .. * .. Intrinsic Functions .. INTRINSIC MAX * .. * .. Executable Statements .. * INFO = 0 * IF( LSAME( UPLO , 'U' ) ) THEN IUPLO = IUPPER ELSE IF( LSAME( UPLO , 'L' ) ) THEN IUPLO = ILOWER ELSE IF( INFO.EQ.0 ) THEN INFO = 1 END IF * IF( INFO.EQ.0 ) THEN IF( N.LT.0 ) THEN INFO = 2 ELSE IF( LDA.LT.MAX( 1, N ) ) THEN INFO = 5 ELSE IF( INCX.EQ.0 ) THEN INFO = 7 ELSE IF( INCY.EQ.0 ) THEN INFO = 10 END IF END IF * IF( INFO.NE.0 ) THEN CALL XERBLA( 'SSYMV ', INFO ) RETURN END IF * CALL ATL_F77WRAP_SSYMV( IUPLO, N, ALPHA, A, LDA, X, INCX, $ BETA, Y, INCY ) * RETURN * * End of SSYMV * END