BLAS/SRC/chpr.f(3)

💖 NAME 💖

BLAS/SRC/chpr.f — bestie, this is the page for chpr, and it's literally the hermitian rank 1 update glow-up. No cap.

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines

• subroutine chpr (uplo, n, alpha, x, incx, ap) — CHPR, she's the whole moment 💅

🦋 Function/Subroutine Documentation

• subroutine chpr (character uplo, integer n, real alpha, complex, dimension(*) x, integer incx, complex, dimension(*) ap) — CHPR again, our icon 👑

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🌸 Purpose

okay so CHPR performs the hermitian rank 1 operation

   A := alpha*x*x**H + A,

where alpha is a real scalar, x is an n element vector and A is an n by n hermitian matrix, supplied in packed form. it's giving "rank-1 update but make it packed" ✨

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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. like, zero is fine, negative is NOT the vibe 🚫
• ALPHA — ALPHA is REAL. On entry, ALPHA specifies the scalar alpha. that's it, that's the tea ☕
• 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.
• INCX — INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. fr fr, zero is not allowed 💀
• 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. On exit, the array AP is overwritten by the upper triangular part of the updated matrix. 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. On exit, the array AP is overwritten by the lower triangular part of the updated matrix. Note that the imaginary parts of the diagonal elements need not be set, they are assumed to be zero, and on exit they are set to zero. periodt 💅

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👑 Author

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

the legends themselves, we stan 🫶

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🔥 Further Details:

Level 2 Blas routine.

   -- 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.

1986?? the way this routine is older than basically everyone and still ate 😭 iconic behavior.

Definition at line 129 of file chpr.f.

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💜 Author

Generated automatically by Doxygen for LAPACK from the source code. not me being a robot-generated page and still serving looks 🤖✨

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Version 3.12.0 · Tue Nov 28 2023 12:08:41 — that's the footer bestie, so this whole page is BLAS/SRC/chpr.f(3), version 3.12.0, dated Tue Nov 28 2023 at 12:08:41, and that's the vibe check, we're done here 🎀💖✨