BLAS/SRC/chpmv.f(3)

💖 BLAS/SRC/chpmv.f(3) — LAPACK 💖

okay bestie, welcome to the chpmv page, straight outta BLAS/SRC/chpmv.f(3) in the LAPACK manual. it's giving "level 2 BLAS, hermitian packed matrix, main character energy" and i'm obsessed. let's get into it 🦋

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✨ NAME ✨

BLAS/SRC/chpmv.f

like... that's the file. that's the whole name. iconic of her tbh 💅

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🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine chpmv (uplo, n, alpha, ap, x, incx, beta, y, incy) — CHPMV

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🎀 Function/Subroutine Documentation 🎀

subroutine chpmv (character uplo, integer n, complex alpha, complex,
    dimension(*) ap, complex, dimension(*) x, integer incx, complex beta,
    complex, dimension(*) y, integer incy)

CHPMV

⭐ Purpose

okay so CHPMV 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, supplied in packed form. periodt. ✨

🫶 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, and it goes like this:

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. And bestie, N must be at least zero. like, zero is the floor, no going lower 💀

• ALPHA

ALPHA is COMPLEX

On entry, ALPHA specifies the scalar alpha. just a lil scalar doing her thing 🎀

• AP

AP is COMPLEX 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 hermitian 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. like a lil stack of triangles, one column at a time 🧚

Before entry with UPLO = 'L' or 'l', the array AP must contain the lower triangular part of the hermitian 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.

Note that the imaginary parts of the diagonal elements need not be set and are assumed to be zero. so like... don't stress about them, they're already zero in spirit 🙈

• X

X is COMPLEX array, dimension at least

( 1 + ( n - 1 )*abs( INCX ) ).

Before entry, the incremented array X must contain the n element vector x. slay 💅

• INCX

INCX is INTEGER

On entry, INCX specifies the increment for the elements of X. and heads up: INCX must not be zero. fr fr, zero is not the vibe. 🚫

• BETA

BETA is COMPLEX

On entry, BETA specifies the scalar beta. When BETA is supplied as zero then Y need not be set on input. so if beta's a zero, Y gets to stay in bed, no cap 😭

• Y

Y is COMPLEX 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. so like, she goes in as one thing and comes out transformed, glow-up arc 💖

• INCY

INCY is INTEGER

On entry, INCY specifies the increment for the elements of Y. INCY must not be zero. same rule, bestie, we do not do zero increments here 🌈

👑 Author

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

the whole squad, respectfully 💜

🔥 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.

like, 1986?? the way these legends were out here writing level 2 BLAS before i was even a thought. historical icons, periodt ⭐

📍 Definition

Definition at line 148 of file chpmv.f.

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🌟 Author (the meta one) 🌟

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a lil robot doing her best 🤖💕

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okay that's the whole page bestie, you're now fully fluent in chpmv. go forth and multiply your hermitian packed matrices 💖✨

Version 3.12.0 — Tue Nov 28 2023 12:08:41 — BLAS/SRC/chpmv.f(3) 🎀 bye ily, see you in the next manpage 🫶