CHEMM(3)

💖 NAME 💖

Bestie, this is the page for chemm.f(3), and the manual name is Library Functions Manual — so we're in Unix-manpage land, but make it fashion. The source file is:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/chemm.f

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine CHEMM (side, uplo, m, n, alpha, a, lda, b, ldb, beta, c, ldc)
    CHEMM

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🦋 Function/Subroutine Documentation 🦋

Here's the full signature, copied exactly because we do not mess with Fortran signatures, periodt:

subroutine CHEMM (character side, character uplo, integer m, integer n,
    complex alpha, complex, dimension(lda,*) a, integer lda, complex,
    dimension(ldb,*) b, integer ldb, complex beta, complex, dimension(ldc,*)
    c, integer ldc)
    CHEMM

🌸 Purpose 🌸

Okay so CHEMM performs one of the matrix-matrix operations, and the source comment says it like this:

!>
!> CHEMM  performs one of the matrix-matrix operations
!>
!>    C := alpha*A*B + beta*C,
!>
!> or
!>
!>    C := alpha*B*A + beta*C,
!>
!> where alpha and beta are scalars, A is an hermitian matrix and  B and
!> C are m by n matrices.
!>

Translation for the group chat: alpha and beta are scalars, A is hermitian, and B and C are m by n matrices. Slay. 💅

👑 Parameters 👑

• SIDE — SIDE is CHARACTER*1. On entry, SIDE specifies whether the hermitian matrix A appears on the left or right in the operation, like this:
  • SIDE = 'L' or 'l' → C := alpha*A*B + beta*C
  • SIDE = 'R' or 'r' → C := alpha*B*A + beta*C
• UPLO — UPLO is CHARACTER*1. On entry, UPLO specifies whether the upper or lower triangular part of the hermitian matrix A is to be referenced:
  • UPLO = 'U' or 'u' → only the upper triangular part of the hermitian matrix is to be referenced.
  • UPLO = 'L' or 'l' → only the lower triangular part of the hermitian matrix is to be referenced.
• M — M is INTEGER. On entry, M specifies the number of rows of the matrix C. M must be at least zero.
• N — N is INTEGER. On entry, N specifies the number of columns of the matrix C. N must be at least zero.
• ALPHA — ALPHA is COMPLEX. On entry, ALPHA specifies the scalar alpha.
• A — A is COMPLEX array, dimension ( LDA, ka ), where ka is m when SIDE = 'L' or 'l' and is n otherwise. Here's the whole situation:
  • Before entry with SIDE = 'L' or 'l', the m by m part of the array A must contain the hermitian matrix, such that:
    • when UPLO = 'U' or 'u', the leading m by m upper triangular part of the array A must contain the upper triangular part of the hermitian matrix, and the strictly lower triangular part of A is not referenced;
    • when UPLO = 'L' or 'l', the leading m by m lower triangular part of the array A must contain the lower triangular part of the hermitian matrix, and the strictly upper triangular part of A is not referenced.
  • Before entry with SIDE = 'R' or 'r', the n by n part of the array A must contain the hermitian matrix, such that:
    • when UPLO = 'U' or 'u', the leading n by n upper triangular part of the array A must contain the upper triangular part of the hermitian matrix, and the strictly lower triangular part of A is not referenced;
    • when UPLO = 'L' or 'l', the leading n by n lower triangular part of the array A must contain the lower triangular part of the hermitian matrix, and the strictly upper triangular part of A is not referenced.
  • Note that the imaginary parts of the diagonal elements need not be set, they are assumed to be zero.
• 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 ), otherwise LDA must be at least max( 1, n ).
• B — B is COMPLEX array, dimension ( LDB, N ). Before entry, the leading m by n part of the array B must contain the matrix B.
• 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 ).
• BETA — BETA is COMPLEX. On entry, BETA specifies the scalar beta. When BETA is supplied as zero then C need not be set on input.
• C — C is COMPLEX array, dimension ( LDC, N ). Before entry, the leading m by n part of the array C must contain the matrix C, except when beta is zero, in which case C need not be set on entry. On exit, the array C is overwritten by the m by n updated matrix.
• LDC — LDC is INTEGER. On entry, LDC specifies the first dimension of C as declared in the calling (sub) program. LDC must be at least max( 1, m ).

🌈 Author 🌈

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

⭐ Further Details ⭐

The source says it's a Level 3 Blas routine, and then gives the vintage receipt:

!>
!>  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 190 of file chemm.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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And that's the whole page, bestie. The footer vibes are: LAPACK Version 3.12.0, source path /home/abui...SRC/chemm.f(3). Iconic. 🫶💖