BLAS/SRC/strmm.f(3)

💖 BLAS/SRC/strmm.f 💖

okay bestie, buckle up, because this is the Fortran file that lives at BLAS/SRC/strmm.f and it is lowkey a legend. it's a LAPACK/BLAS situation and it's giving "triangular matrix times matrix" realness. no cap. 🦋

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines

• subroutine strmm (side, uplo, transa, diag, m, n, alpha, a, lda, b, ldb) — this is the one and only STRMM, she's the whole moment 💅

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🌸 Function/Subroutine Documentation 🌸

subroutine strmm (character side, character uplo, character transa, character diag, integer m, integer n, real alpha, real, dimension(lda,*) a, integer lda, real, dimension(ldb,*) b, integer ldb)

STRMM

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💜 Purpose:

STRMM performs one of the matrix-matrix operations

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

where alpha is a scalar, B is an m by n matrix, 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.

so yeah, it's literally the triangular-matrix glow-up machine ✨

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🌈 Parameters

• SIDE — SIDE is CHARACTER*1. on entry, SIDE specifies whether op( A ) multiplies B from the left or right, like this:
  • SIDE = 'L' or 'l' → B := alpha*op( A )*B.
  • SIDE = 'R' or 'r' → B := alpha*B*op( A ).
• UPLO — UPLO is CHARACTER*1. on entry, UPLO specifies whether the matrix A is an upper or lower triangular matrix, bestie:
  • 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, and it goes like:
  • 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. (zero is the floor, periodt)
• N — N is INTEGER. on entry, N specifies the number of columns of B. N must be at least zero.
• ALPHA — ALPHA is REAL. on entry, ALPHA specifies the scalar alpha. when alpha is zero then A is not referenced and B need not be set before entry. (so you can just... skip the setup? iconic behaviour fr fr 🙈)
• A — A is REAL array, dimension ( LDA, k ), where k is m when SIDE = 'L' or 'l' and 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. ✨
• 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 REAL array, dimension ( LDB, N ). before entry, the leading m by n part of the array B must contain the matrix B, and on exit is overwritten by the transformed matrix. (she gets a whole new look, no cap 💅)
• 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 ).

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👑 Author

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

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🧚 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.

fr, these four wrote this thing back in 1989 and it's still out here slaying in every BLAS build. main character energy since day one. 🫶

Definition at line 176 of file strmm.f.

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⭐ Author

Generated automatically by Doxygen for LAPACK from the source code.

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okay that's the whole page, bestie 💖 that was LAPACK, Version 3.12.0, dated Tue Nov 28 2023 12:08:41, and yeah it's still BLAS/SRC/strmm.f(3) at the end of the day. go forth and multiply your triangular matrices, but like, correctly. slay ✨🌈