BLAS/SRC/strsv.f(3)

💖 BLAS/SRC/strsv.f — the vibe 💖

okay bestie, this page lives in LAPACK's BLAS/SRC folder, and it's literally the manual for strsv.f 🦋

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✨ NAME ✨

BLAS/SRC/strsv.f — that's the file, that's the whole name, no notes 💅

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🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine strsv (uplo, trans, diag, n, a, lda, x, incx) — STRSV, the icon herself 👑

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🎀 Function/Subroutine Documentation 🎀

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

STRSV ✨

Purpose:

so here's the tea, bestie — STRSV solves one of these systems of equations:

A*x = b,   or   A**T*x = b,

where b and x are n element vectors and A is an n by n unit, or non-unit, upper or lower triangular matrix. that's it, that's the job 💜

okay real talk though, no cap: no test for singularity or near-singularity is included in this routine. such tests must be performed before calling this routine. like, it will NOT warn you, it will NOT check, it's giving "not my job" energy 😭 do your own vibe check first, fr fr.

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 equations to be solved as follows:

• TRANS = 'N' or 'n' — A*x = b.
• TRANS = 'T' or 't' — A**T*x = b.
• TRANS = 'C' or 'c' — A**T*x = b.

• 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.

• 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. ✨ (iconic behaviour honestly, we love a shortcut)

• 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 right-hand side vector b. On exit, X is overwritten with the solution vector x. 🦋 she gets a whole glow-up on the way out.

• INCX

INCX is INTEGER. On entry, INCX specifies the increment for the elements of X. INCX must not be zero. 🚫 seriously bestie, zero is not it.

Author

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

Further Details:

• Level 2 Blas routine. 💅
• Written on 22-October-1986. (yes, the 80s. vintage. iconic. periodt.)
  • Jack Dongarra, Argonne National Lab.
  • Jeremy Du Croz, Nag Central Office.
  • Sven Hammarling, Nag Central Office.
  • Richard Hanson, Sandia National Labs.

Definition at line 148 of file strsv.f. 📍

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code. (not me, a robot did this, and honestly? she ate 🤖✨)

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and that's the whole page bestie, no notes, no cap 🫶

Version 3.12.0 — Tue Nov 28 2023 12:08:41 — BLAS/SRC/strsv.f(3) 🌈 ty for coming to my ted talk, go solve your triangular systems, mwah 💋