BLAS/SRC/dspmv.f(3)

💖 NAME 💖

Welcome to BLAS/SRC/dspmv.f(3), bestie — this is the Library Functions Manual entry for BLAS/SRC/dspmv.f. It's literally the page for the dspmv subroutine, and we're gonna get into all of it ✨

✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine dspmv (uplo, n, alpha, ap, x, incx, beta, y, incy) — DSPMV

🦋 Function/Subroutine Documentation 🦋

subroutine dspmv

Here's the full signature, exactly as the page gives it:

       subroutine dspmv (character uplo, integer n, double precision alpha, double
       precision, dimension(*) ap, double precision, dimension(*) x, integer
       incx, double precision beta, double precision, dimension(*) y, integer
       incy)

DSPMV

Purpose:

DSPMV 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, supplied in packed form.

Parameters

• UPLO — UPLO is 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.
• N — N is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero.
• ALPHA — ALPHA is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha.
• AP — AP is DOUBLE PRECISION array, 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 symmetric 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 symmetric 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.
• X — X is DOUBLE PRECISION array, dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x.
• INCX — INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero.
• BETA — BETA is DOUBLE PRECISION. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input.
• Y — Y is DOUBLE PRECISION array, 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 — INCY is INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero.

Author

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Further Details:

• Level 2 Blas routine.
• The vector and matrix arguments are not referenced when N = 0, or M = 0
• -- 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.

Definition at line 146 of file dspmv.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

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okay bestie, that's the whole vibe 💖 this page is LAPACK Version 3.12.0, for BLAS/SRC/dspmv.f(3), and the source code was originally written on 22-October-1986 — catch you later, mwah 💋✨