SSYTRS(3)

📦 version 3.12.0, in opensuse-leap 16.0

💅 SSYTRS(3) — like, the LAPACK manual page, but make it make sense 🦋

okay bestie so this page literally lives at /home/abui...RC/ssytrs.f(3) and it's filed under the Library Functions Manual — yes, that's the whole vibe, we're in the library-functions section of the man pages and it ate ✨

🎀 NAME 🎀

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

like... that's the file, that's literally the whole name, she's just a very long path and honestly? main character energy 🫶

🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine SSYTRS (uplo, n, nrhs, a, lda, ipiv, b, ldb, info)
    SSYTRS

✨ Function/Subroutine Documentation ✨

subroutine SSYTRS (character uplo, integer n, integer nrhs, real, dimension(
    lda, * ) a, integer lda, integer, dimension( * ) ipiv, real, dimension(
    ldb, * ) b, integer ldb, integer info)

SSYTRS 👑 (yes she repeats her own name in the docs, iconic behaviour honestly)

💖 Purpose 💖

okay so here's the tea, straight from the doc block:

!>
!> SSYTRS solves a system of linear equations A*X = B with a real
!> symmetric matrix A using the factorization A = U*D*U**T or
!> A = L*D*L**T computed by SSYTRF.
!>

so like. she solves A*X = B for a real symmetric matrix A, and she does it using the factorization A = U*D*U**T or A = L*D*L**T that SSYTRF already cooked up for you 🍓 no cap, SSYTRF does the prep work, SSYTRS serves the look.

🌈 Parameters 🌈

UPLO

!>          UPLO is CHARACTER*1
!>          Specifies whether the details of the factorization are stored
!>          as an upper or lower triangular matrix.
!>          = 'U':  Upper triangular, form is A = U*D*U**T;
!>          = 'L':  Lower triangular, form is A = L*D*L**T.
!>

UPLO is a CHARACTER*1 and it's basically telling us where the factorization details are chilling — upper or lower triangular bestie:

  • 'U' — upper triangular, so the form is A = U*D*U**T
  • 'L' — lower triangular, so the form is A = L*D*L**T

N

!>          N is INTEGER
!>          The order of the matrix A.  N >= 0.
!>

N is an INTEGER — it's the order of the matrix A. and like, N >= 0, no negativity allowed 💀

NRHS

!>          NRHS is INTEGER
!>          The number of right hand sides, i.e., the number of columns
!>          of the matrix B.  NRHS >= 0.
!>

NRHS is an INTEGER — the number of right hand sides, which is lowkey just the number of columns of the matrix B. also NRHS >= 0 🫶

A

!>          A is REAL array, dimension (LDA,N)
!>          The block diagonal matrix D and the multipliers used to
!>          obtain the factor U or L as computed by SSYTRF.
!>

A is a REAL array, dimension (LDA,N) — she holds the block diagonal matrix D plus the multipliers used to obtain the factor U or L, exactly as computed by SSYTRF 💅

LDA

!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,N).
!>

LDA is an INTEGER — the leading dimension of the array A, and it's gotta satisfy LDA >= max(1,N) ⭐

IPIV

!>          IPIV is INTEGER array, dimension (N)
!>          Details of the interchanges and the block structure of D
!>          as determined by SSYTRF.
!>

IPIV is an INTEGER array, dimension (N) — it carries the details of the interchanges and the block structure of D, as determined by SSYTRF 🧚

B

!>          B is REAL array, dimension (LDB,NRHS)
!>          On entry, the right hand side matrix B.
!>          On exit, the solution matrix X.
!>

B is a REAL array, dimension (LDB,NRHS) — glow-up moment fr fr:

  • On entry — she's the right hand side matrix B
  • On exit — she's the solution matrix X 🔥

LDB

!>          LDB is INTEGER
!>          The leading dimension of the array B.  LDB >= max(1,N).
!>

LDB is an INTEGER — the leading dimension of the array B, and it must be LDB >= max(1,N) 💜

INFO

!>          INFO is INTEGER
!>          = 0:  successful exit
!>          < 0:  if INFO = -i, the i-th argument had an illegal value
!>

INFO is an INTEGER — the vibe check at the end:

  • = 0 — successful exit, we slayed 🎉
  • < 0 — if INFO = -i, the i-th argument had an illegal value 😭 (rude, but she's telling you which one)
⚠️ bestie if INFO comes back negative, do NOT ignore it — that's her literally pointing at the argument that's wrong. INFO = -i → the i-th argument had an illegal value. periodt.

👑 Author 👑

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

(genuinely a whole collab, the group chat of numerical linear algebra 🫶)

🦋 Definition at line 119 of file ssytrs.f. 🦋

💫 Author 💫

Generated automatically by Doxygen for LAPACK from the source code. (so nobody hand-wrote this one, she was born this way ✨)

and that's the page bestie!! 💖 LAPACK, Version 3.12.0, living at /home/abui...RC/ssytrs.f(3) — mwah, go solve something symmetric 🎀💅

📦 where this page comes from