BLAS/SRC/dtrsm.f(3)

📦
version 3.12.0 · 7 versions
, in centos-stream 10, fedora 43, fedora 44

💖 BLAS/SRC/dtrsm.f(3) 💖

okay bestie, gather round, because we're reading a LAPACK page together and honestly? it's giving iconic BLAS energy. this one lives in LAPACK under BLAS/SRC/dtrsm.f(3) and it's about to solve some triangular matrix equations with you. no cap. 🦋

✨ NAME ✨

BLAS/SRC/dtrsm.f — that's the file, that's the whole name section, periodt. 💅

🌸 SYNOPSIS 🌸

Functions/Subroutines

  • subroutine dtrsm (side, uplo, transa, diag, m, n, alpha, a, lda, b, ldb) — the moment we've all been waiting for: DTRSM itself 👑

🎀 Function/Subroutine Documentation 🎀

subroutine dtrsm (character side, character uplo, character transa, character diag, integer m, integer n, double precision alpha, double precision, dimension(lda,*) a, integer lda, double precision, dimension(ldb,*) b, integer ldb)

DTRSM ⭐

💜 Purpose:

so like, DTRSM solves one of these matrix equations:

op( A )*X = alpha*B,   or   X*op( A ) = alpha*B,

where alpha is a scalar, X and B are m by n matrices, A is a unit, or non-unit, upper or lower triangular matrix and op( A ) is one of

op( A ) = A   or   op( A ) = A**T.

and the way that the matrix X just gets overwritten on B?? efficiency icon behavior fr fr. 💖

🌈 Parameters

  • SIDE

SIDE is CHARACTER*1

On entry, SIDE specifies whether op( A ) appears on the left or right of X as follows:

  • SIDE = 'L' or 'l' — op( A )*X = alpha*B.
  • SIDE = 'R' or 'r' — X*op( A ) = alpha*B.
  • UPLO

UPLO is CHARACTER*1

On entry, UPLO specifies whether the matrix A 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.
  • TRANSA

TRANSA is CHARACTER*1

On entry, TRANSA specifies the form of op( A ) to be used in the matrix multiplication as follows:

  • TRANSA = 'N' or 'n' — op( A ) = A.
  • TRANSA = 'T' or 't' — op( A ) = A**T.
  • TRANSA = 'C' or 'c' — op( A ) = A**T.
  • 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.
  • M

M is INTEGER

On entry, M specifies the number of rows of B. M must be at least zero. (yes bestie, at least zero, we don't do negative rows here 🙈)

  • N

N is INTEGER

On entry, N specifies the number of columns of B. N must be at least zero.

  • ALPHA

ALPHA is DOUBLE PRECISION.

On entry, ALPHA specifies the scalar alpha. When alpha is zero then A is not referenced and B need not be set before entry. that's the free real estate right there 💀

  • A

A is DOUBLE PRECISION array, dimension ( LDA, k ), where k is m when SIDE = 'L' or 'l' and k is n when SIDE = 'R' or 'r'.

Before entry with UPLO = 'U' or 'u', the leading k by k 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 k by k 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. lowkey they're just vibing, untouched, assumed perfect. ✨

  • LDA

LDA is INTEGER

On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. When SIDE = 'L' or 'l' then LDA must be at least max( 1, m ), when SIDE = 'R' or 'r' then LDA must be at least max( 1, n ).

  • B

B is DOUBLE PRECISION array, dimension ( LDB, N )

Before entry, the leading m by n part of the array B must contain the right-hand side matrix B, and on exit is overwritten by the solution matrix X. she transforms, she's the main character now 👑

  • LDB

LDB is INTEGER

On entry, LDB specifies the first dimension of B as declared in the calling (sub) program. LDB must be at least max( 1, m ).

🫶 Author

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

💫 Further Details:

  • Level 3 Blas routine.
  • -- Written on 8-February-1989. Jack Dongarra, Argonne National Laboratory. Iain Duff, AERE Harwell. Jeremy Du Croz, Numerical Algorithms Group Ltd. Sven Hammarling, Numerical Algorithms Group Ltd.
not the 1989 date?? these legends really said "we'll write the BLAS and it'll outlive us all" and they were SO right. 🔥👑

📍 Definition at line 180 of file dtrsm.f.

🧚 Author

Generated automatically by Doxygen for LAPACK from the source code. (yes bestie, a robot wrote this page, we're just here to make it cute 🎀)

and that's the whole page!! tysm for reading, you understood all of it, no notes, slay. 💖✨

LAPACK Version 3.12.0 — Tue Nov 28 2023 12:08:41 — mwah, love u, go solve a triangular system 🦋💅🌸

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