DSYRK(3)

💅 DSYRK(3) — the symmetric rank-k update, bestie edition 🌸

ok so first things first: this page lives in the LAPACK manual (that's the library-name situation, iykyk), and the file it's documenting is literally this one right here:

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

that's the NAME, that's the file, we move 💫

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines

subroutine DSYRK (uplo, trans, n, k, alpha, a, lda, beta, c, ldc)

DSYRK 🫶

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📖 Function/Subroutine Documentation 📖

subroutine DSYRK (character uplo, character trans, integer n, integer k,
    double precision alpha, double precision, dimension(lda,*) a, integer
    lda, double precision beta, double precision, dimension(ldc,*) c,
    integer ldc)

DSYRK — that's her name, that's the whole girl 💅

🎯 Purpose 🎯

no cap, DSYRK performs one of the symmetric rank k operations:

C := alpha*A*A**T + beta*C,

or

C := alpha*A**T*A + beta*C,

where alpha and beta are scalars, C is an n by n symmetric matrix, and A is an n by k matrix in the first case and a k by n matrix in the second case. periodt ✨

🌈 Parameters 🌈

💜 UPLO

UPLO is CHARACTER*1.

on entry, UPLO specifies whether the upper or lower triangular part of the array C is to be referenced, as follows:

• UPLO = 'U' or 'u' — only the upper triangular part of C is to be referenced.
• UPLO = 'L' or 'l' — only the lower triangular part of C is to be referenced.

💜 TRANS

TRANS is CHARACTER*1.

on entry, TRANS specifies the operation to be performed as follows:

• TRANS = 'N' or 'n' — C := alpha*A*A**T + beta*C.
• TRANS = 'T' or 't' — C := alpha*A**T*A + beta*C.
• TRANS = 'C' or 'c' — C := alpha*A**T*A + beta*C.

(yeah 'T' and 'C' do the exact same thing here, she's not doing anything different, slay 💀)

💜 N

N is INTEGER.

on entry, N specifies the order of the matrix C. N must be at least zero 🫶

💜 K

K is INTEGER.

on entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrix A, and on entry with TRANS = 'T' or 't' or 'C' or 'c', K specifies the number of rows of the matrix A. K must be at least zero ⭐

💜 ALPHA

ALPHA is DOUBLE PRECISION.

on entry, ALPHA specifies the scalar alpha. iconic, no notes 🎀

💜 A

A is DOUBLE PRECISION array, dimension ( LDA, ka ), where ka is k when TRANS = 'N' or 'n', and is n otherwise.

before entry with TRANS = 'N' or 'n', the leading n by k part of the array A must contain the matrix A, otherwise the leading k by n part of the array A must contain the matrix A. 🦋

💜 LDA

LDA is INTEGER.

on entry, LDA specifies the first dimension of A as declared in the calling (sub) program. when TRANS = 'N' or 'n' then LDA must be at least max( 1, n ), otherwise LDA must be at least max( 1, k ). do not get this wrong bestie, she WILL read the wrong memory 😭

💜 BETA

BETA is DOUBLE PRECISION.

on entry, BETA specifies the scalar beta. 💖

💜 C

C is DOUBLE PRECISION array, dimension ( LDC, N ).

before entry with UPLO = 'U' or 'u', the leading n by n upper triangular part of the array C must contain the upper triangular part of the symmetric matrix and the strictly lower triangular part of C is not referenced. on exit, the upper triangular part of the array C is overwritten by the upper triangular part of the updated matrix.

before entry with UPLO = 'L' or 'l', the leading n by n lower triangular part of the array C must contain the lower triangular part of the symmetric matrix and the strictly upper triangular part of C is not referenced. on exit, the lower triangular part of the array C is overwritten by the lower triangular part of the updated matrix.

🫶 quick vibe check: the other triangle literally does not get looked at. not read, not written. so don't be out here storing your whole life in it and expecting it back, because she did not touch it, fr fr.

💜 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, n ). 👑

👑 Author 👑

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

(the whole squad gets credit, as they should 💅)

🔥 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.

written in 1989 and still main character energy, we love to see it ⭐

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Definition at line 168 of file dsyrk.f.

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🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code. (yes bestie, a robot wrote this bit, not me 🙈)

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that's the whole page!! 💖✨🦋 this was LAPACK, Version 3.12.0, documented from /home/abui...SRC/dsyrk.f(3) — mwah, go call your BLAS routines, ily 🫶🌸