STRMV(3)

💅 STRMV(3) — the triangular matrix-vector glow-up 💅

okay bestie, so this is a page from the LAPACK library functions manual, and it lives at /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/strmv.f 🫶 (yes that's a whole address, she's got main character energy AND a long home directory).

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✨ SYNOPSIS ✨

Functions/Subroutines:

subroutine STRMV (uplo, trans, diag, n, a, lda, x, incx)
    STRMV

🦋 Function/Subroutine Documentation 🦋

subroutine STRMV (character uplo, character trans, character diag, integer
    n, real, dimension(lda,*) a, integer lda, real, dimension(*) x, integer
    incx)

STRMV — that's her name, that's her whole thing 💖

Purpose:

!>
!> STRMV  performs one of the matrix-vector operations
!>
!>    x := A*x,   or   x := A**T*x,
!>
!> where x is an n element vector and  A is an n by n unit, or non-unit,
!> upper or lower triangular matrix.
!>

so literally she takes your triangular matrix A and multiplies it into your vector x — either a straight x := A*x or the transposed x := A**T*x — and hands you back a transformed x. no cap, that's it, that's the vibe 🔥

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🌸 Parameters 🌸

• UPLO — UPLO is CHARACTER*1. On entry, UPLO specifies whether the matrix is an upper or lower triangular matrix as follows:
  • UPLO = 'U' or 'u' — A is an upper triangular matrix.
  • UPLO = 'L' or 'l' — A is a lower triangular matrix.
• TRANS — TRANS is CHARACTER*1. On entry, TRANS specifies the operation to be performed as follows:
  • TRANS = 'N' or 'n' — x := A*x.
  • TRANS = 'T' or 't' — x := A**T*x.
  • TRANS = 'C' or 'c' — x := A**T*x.

(yes 'T' and 'C' do the exact same thing here, she's not gonna pretend otherwise 🙈)

• DIAG — DIAG is CHARACTER*1. On entry, DIAG specifies whether or not A is unit triangular as follows:
  • DIAG = 'U' or 'u' — A is assumed to be unit triangular.
  • DIAG = 'N' or 'n' — A is not assumed to be unit triangular.
• N — N is INTEGER. On entry, N specifies the order of the matrix A. N must be at least zero. (zero is fine, she's chill like that 🧚)
• A — A is REAL 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 matrix and the strictly lower triangular part of A is not referenced.
  • Before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array A must contain the lower triangular matrix and the strictly upper triangular part of A is not referenced.
  • Note that when DIAG = 'U' or 'u', the diagonal elements of A are not referenced either, but are assumed to be unity.

💀 real talk: those unreferenced chunks? she does NOT look at them. don't come for her.

• 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 ). ✨
• X — X is REAL array, dimension at least ( 1 + ( n - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the n element vector x. On exit, X is overwritten with the transformed vector x. 😭 she really said "your input is my output now" and honestly? iconic.
• INCX — INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. ⭐ (fr fr, zero will ruin her whole day)

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👑 Author 👑

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

the whole squad behind it, we love a collaborative slay 🫶

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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.
!>

so she's a Level 2 Blas routine, and the vector and matrix arguments are not referenced when N = 0, or M = 0 — literally nothing gets touched, she's resting 💅

and she was written on 22-October-1986 by Jack Dongarra (Argonne National Lab.), Jeremy Du Croz (Nag Central Office.), Sven Hammarling (Nag Central Office.) and Richard Hanson (Sandia National Labs.) — vintage but still serving, we stan a legend 🌈

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Definition at line 146 of file strmv.f. 📍

💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code. 🎀

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okay that's the whole page bestie, you're officially STRMV-pilled 🦋 and yeah — LAPACK, Version 3.12.0, dated /home/abui...SRC/strmv.f(3) — that's the sign-off, mwah 💋 periodt ✨