/home/abui...C/zsyr2k.f(3)

💅 ZSYR2K 💅

okay so this is straight out of the Library Functions Manual (the LAPACK one, bestie) and the file it lives in is literally called /home/abui...C/zsyr2k.f(3) — cute, right? anyway. sit down. we're doing symmetric rank-2k updates and honestly? it's giving iconic. 🦋

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🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/BLAS/SRC/zsyr2k.f

yes bestie that is the whole name, it's a whole ass path, do not come for me, that's just how the build directory is set up. 🎀

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✨ SYNOPSIS ✨

Functions/Subroutines

• subroutine ZSYR2K (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c, ldc) — that's the one. that's ZSYR2K. main character energy fr fr 👑

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🫶 Function/Subroutine Documentation 🫶

subroutine ZSYR2K (character uplo, character trans, integer n, integer k,
    complex*16 alpha, complex*16, dimension(lda,*) a, integer lda,
    complex*16, dimension(ldb,*) b, integer ldb, complex*16 beta,
    complex*16, dimension(ldc,*) c, integer ldc)

ZSYR2K. (yes it's just its own name up there, it's a whole thing, we don't question it 💀)

🎀 Purpose 🎀

okay so lowkey here's the whole vibe. ZSYR2K performs one of the symmetric rank 2k operations:

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

or

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

where alpha and beta are scalars, C is an n by n symmetric matrix, and A and B are n by k matrices in the first case and k by n matrices in the second case. no cap, that's the whole thing. 🔥

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💜 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, like this:
  • 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*B**T + alpha*B*A**T + beta*C.
  • TRANS = 'T' or 't' — C := alpha*A**T*B + alpha*B**T*A + beta*C.
• N — N is INTEGER. on entry, N specifies the order of the matrix C. N must be at least zero. (at least zero, bestie, we do not do negative orders here 🙈)
• K — K is INTEGER. on entry with TRANS = 'N' or 'n', K specifies the number of columns of the matrices A and B, and on entry with TRANS = 'T' or 't', K specifies the number of rows of the matrices A and B. K must be at least zero. same energy, also at least zero 💅
• ALPHA — ALPHA is COMPLEX*16. on entry, ALPHA specifies the scalar alpha. that's it. that's the whole parameter. slay 🌸
• A — A is COMPLEX*16 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. literally just put the matrix in the matrix, iykyk 🦋
• 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 ). write that down. 🎀
• B — B is COMPLEX*16 array, dimension ( LDB, kb ), where kb 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 B must contain the matrix B; otherwise the leading k by n part of the array B must contain the matrix B. yes it's the exact same deal as A, it's a matching set, they're twins 👑
• LDB — LDB is INTEGER. on entry, LDB specifies the first dimension of B as declared in the calling (sub) program. when TRANS = 'N' or 'n' then LDB must be at least max( 1, n ), otherwise LDB must be at least max( 1, k ). twins again, obsessed. ✨
• BETA — BETA is COMPLEX*16. on entry, BETA specifies the scalar beta. that's the whole description, it's short and it knows it. 💅
• C — C is COMPLEX*16 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. (so like. it gets rewritten. be aware. 😭)
  • 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.
• 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 ). that's non-negotiable bestie 🫶

👑 Author 👑

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

look at that lineup. four whole legends. we stan. 🌈

⭐ 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.

okay 1989?? they were doing this before i was even a thought. respect. genuinely iconic behaviour. 🧚

Definition at line 187 of file zsyr2k.f.

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💖 Author 💖

Generated automatically by Doxygen for LAPACK from the source code. yes it wrote itself basically, it's self-made, it's independent, we love that for it. 🙈

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and that's the page, bestie!! brought to you by LAPACK, Version 3.12.0 — and the header was all like /home/abui...C/zsyr2k.f(3), which is the file, in case you were wondering. mwah. 💋 go forth and multiply your matrices. 🍓