BLAS/SRC/dtrmm.f(3)

✨ BLAS/SRC/dtrmm.f ✨

ok so bestie, you've stumbled into the LAPACK manual — specifically the BLAS/SRC/dtrmm.f page 💖 (that's the manual name, it lives at the top, i'm just telling you early so you're not confused). this is the DTRMM glow-up page and it's so much less scary than it looks, i promise. 🫶

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🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine dtrmm (side, uplo, transa, diag, m, n, alpha, a, lda, b, ldb) — literally just DTRMM, that's the whole vibe ✨

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🎀 Function/Subroutine Documentation 🎀

subroutine dtrmm (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)

DTRMM 👑

💜 Purpose:

bestie. DTRMM performs one of the matrix-matrix operations, okay:

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.

that's it. that's the whole job. triangular matrix times stuff, scaled by alpha. iconic behavior fr 💅

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🌈 Parameters

• SIDE — SIDE is CHARACTER*1. On entry, SIDE specifies whether op( A ) multiplies B from the left or right as follows:
  • 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 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.

(yes bestie, 'T' and 'C' do the same thing here, that's not a typo, that's canon 🫶)

• M — M is INTEGER. On entry, M specifies the number of rows of B. M must be at least zero.
• 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. (so if you're zeroing it all out, you get a free pass on A, no cap 🌸)
• A — A is DOUBLE PRECISION 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 DOUBLE PRECISION 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. (yeah it gets ate, the original B is gone 💀 that's the whole point tho)
• 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.

Definition at line 176 of file dtrmm.f.

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💖 Author

Generated automatically by Doxygen for LAPACK from the source code.

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and that's the whole page bestie, you ate it 🫶 this was LAPACK version 3.12.0, dated Tue Nov 28 2023 12:08:41, and it's the BLAS/SRC/dtrmm.f(3) page — go forth and multiply your triangles, mwah 💅✨