BLAS/SRC/dsyr.f(3)

💖 BLAS/SRC/dsyr.f 💖

okay bestie, welcome to the manual page for dsyr — a lil file living over in BLAS/SRC/. it's part of the LAPACK fam and honestly? it's giving main character energy in the world of rank-1 updates. let's get into it ✨

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🦋 SYNOPSIS 🦋

Functions/Subroutines

subroutine dsyr (uplo, n, alpha, x, incx, a, lda)

DSYR 💅

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🌸 Function/Subroutine Documentation 🌸

subroutine dsyr

subroutine dsyr (character uplo, integer n, double precision alpha, double
    precision, dimension(*) x, integer incx, double precision,
    dimension(lda,*) a, integer lda)

DSYR 🫶

🎀 Purpose

so what does DSYR actually do, bestie? it performs the symmetric rank 1 operation

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

where alpha is a real scalar, x is an n element vector and A is an n by n symmetric matrix. literally math but make it cute ✨

🌈 Parameters

• UPLO — UPLO is CHARACTER*1. on entry, UPLO specifies whether the upper or lower triangular part of the array A is to be referenced, like this:
  • 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.
• N — N is INTEGER. on entry, N specifies the order of the matrix A. N must be at least zero. (zero is valid, she's inclusive 💜)
• ALPHA — ALPHA is DOUBLE PRECISION. on entry, ALPHA specifies the scalar alpha. the moment, the icon, the multiplier 🔥
• 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. she's bringing the vector to the function, periodt.
• INCX — INCX is INTEGER. on entry, INCX specifies the increment for the elements of X. INCX must not be zero. like, do not do it. that's a hard no. 🙈
• A — A is DOUBLE PRECISION array, dimension ( LDA, N ).
  • before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array A must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of A is not referenced. on exit, the upper triangular part of the array A is overwritten by the upper triangular part of the updated matrix. glow up complete 💖
  • before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of A is not referenced. on exit, the lower triangular part of the array A is overwritten by the lower triangular part of the updated matrix. iconic behaviour, truly.
• LDA — LDA is 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 ). no shrinking her, bestie.

👑 Author

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

the whole squad showed up for this one, we love a collab 🫶

💫 Further Details

Level 2 Blas routine. yep, she's level 2 and she knows it 💅

-- 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.

look at this legendary lineup, actual pioneers fr fr 🌟

⭐ Definition at line 131 of file dsyr.f.

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💜 Author

Generated automatically by Doxygen for LAPACK from the source code. (not me writing this by hand, the robots did it, and honestly? they ate.)

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k that's the whole page bestie, no cap. every flag, every dimension, every warning, all of it. go forth and update your symmetric matrices responsibly 💅✨

Version 3.12.0 · Tue Nov 28 2023 12:08:41 · BLAS/SRC/dsyr.f(3) — mwah, bye! 🎀🦋🌸