BLAS/SRC/dspmv.f(3)

💖 NAME 💖

BLAS/SRC/dspmv.f — it's giving legendary Fortran, no cap ✨ (this is the page for dspmv, straight out of the LAPACK BLAS source tree, bestie)

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🌸 SYNOPSIS 🌸

Functions/Subroutines

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

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✨ Function/Subroutine Documentation ✨

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 🎀

okay so listen. 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. literally that's the whole vibe 💅

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🧚 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. (zero is valid bestie, don't come for me 🙈)

• 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. (free real estate, you're welcome 💅)

• 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. 😭 (she gets rewritten, it's fine, that's her glow-up)

• INCY

INCY is INTEGER. On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. 🚫

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👑 Author 👑

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

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🔥 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.

ngl, 1986?? these icons were doing linear algebra before it was cool. periodt. 💜

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⭐ Definition at line 146 of file dspmv.f. ⭐

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💀 Author 💀

Generated automatically by Doxygen for LAPACK from the source code. (not me being a whole robot-written manpage 🙈✨)

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okay that's the whole page bestie, thanks for reading my ted talk 🎀 this was Version 3.12.0, dated Tue Nov 28 2023 12:08:41, and yes it lives at BLAS/SRC/dspmv.f(3) — slay, bye 💖🦋🌸