BLAS/SRC/dsyr2k.f(3)

📦
version 3.12.0 · 7 versions
, in centos-stream 10, fedora 43, fedora 44

💖 BLAS/SRC/dsyr2k.f(3) 💖

okay bestie, welcome to the LAPACK manual page for BLAS/SRC/dsyr2k.f — yes that's the manual name, we're folding it in right here at the top like a little name tag at a party 🎀

✨ NAME ✨

BLAS/SRC/dsyr2k.f — the file, the moment, the legend 💅

🌸 SYNOPSIS 🌸

Functions/Subroutines

  • subroutine dsyr2k (uplo, trans, n, k, alpha, a, lda, b, ldb, beta, c, ldc) — DSYR2K

🦋 Function/Subroutine Documentation 🦋

subroutine dsyr2k (character uplo, character trans, integer n, integer k, double precision alpha, double precision, dimension(lda,*) a, integer lda, double precision, dimension(ldb,*) b, integer ldb, double precision beta, double precision, dimension(ldc,*) c, integer ldc)

DSYR2K

👑 Purpose:

DSYR2K 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. like. that's the whole vibe. matrix math glow-up fr fr 🔥

🌈 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*B**T + alpha*B*A**T + beta*C.
    • TRANS = 'T' or 't' — C := alpha*A**T*B + alpha*B**T*A + beta*C.
    • TRANS = 'C' or 'c' — 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. (zero is allowed, she's inclusive 💜)
  • 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' or 'C' or 'c', K specifies the number of rows of the matrices A and B. K must be at least zero.
  • ALPHA — ALPHA is DOUBLE PRECISION. On entry, ALPHA specifies the scalar alpha.
  • 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 ).
  • B — B is DOUBLE PRECISION 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.
  • 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 ).
  • 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.
bestie pay attention: the half of C you don't reference is genuinely not touched, and the half you do reference gets overwritten on exit. it's giving "read the half, write the half" 💅
  • 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.

🧚 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 191 of file dsyr2k.f.

💜 Author (again, yes really)

Generated automatically by Doxygen for LAPACK from the source code.

and that's the whole page bestie, no notes, ate and left no crumbs 🎀 — this was Version 3.12.0, dated Tue Nov 28 2023 12:08:41, straight from the BLAS/SRC/dsyr2k.f(3) corner of the LAPACK universe. mwah 💖✨

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