SSYSWAPR(3)

🦋 ssyswapr.f(3) — Library Functions Manual 🦋

okay bestie so this is page ssyswapr.f(3), and it lives in the LAPACK manual — the Library Functions Manual, to be exact. Let's get into it ✨

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💅 NAME

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

that's the file, that's the whole name, she's long and she's iconic, no cap 🎀

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✨ SYNOPSIS

Functions/Subroutines 🌸

• subroutine SSYSWAPR (uplo, n, a, lda, i1, i2) — SSYSWAPR applies an elementary permutation on the rows and columns of a symmetric matrix. that's it, that's the vibe 💖

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👑 Function/Subroutine Documentation

subroutine SSYSWAPR (character uplo, integer n, real, dimension( lda, * ) a,
    integer lda, integer i1, integer i2)

SSYSWAPR applies an elementary permutation on the rows and columns of a symmetric matrix. she's a swapper, she's a permuter, she does one job and she ate 🔥

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🎯 Purpose

!>
!> SSYSWAPR applies an elementary permutation on the rows and the columns of
!> a symmetric matrix.
!>

literally the whole purpose, right there, in a comment block with !> on every line because that's how Fortran doxxes its docstrings 😭

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🧚 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 CHARACTER*1 and it's the main character deciding where the factorization details get stored — upper or lower triangular, bestie, pick a lane 💅

• = 'U' → Upper triangular, form is A = U*D*U**T
• = 'L' → Lower triangular, form is A = L*D*L**T

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• N

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

N is INTEGER, she's the order of the matrix A, and N >= 0. zero is allowed, negative is not, periodt 🙈

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• A

!>          A is REAL array, dimension (LDA,*)
!>          On entry, the N-by-N matrix A. On exit, the permuted matrix
!>          where the rows I1 and I2 and columns I1 and I2 are interchanged.
!>          If UPLO = 'U', the interchanges are applied to the upper
!>          triangular part and the strictly lower triangular part of A is
!>          not referenced; if UPLO = 'L', the interchanges are applied to
!>          the lower triangular part and the part of A above the diagonal
!>          is not referenced.
!>

A is a REAL array, dimension (LDA,*). on entry she's the N-by-N matrix A 🫶 on exit she's the permuted matrix where the rows I1 and I2 and columns I1 and I2 are interchanged. glow-up fr fr.

and like, pay attention to the fine print because this part matters:

• if UPLO = 'U', the interchanges are applied to the upper triangular part, and the strictly lower triangular part of A is not referenced
• if UPLO = 'L', the interchanges are applied to the lower triangular part, and the part of A above the diagonal is not referenced

so like, half of A is just sitting there unbothered, not even looked at 💀

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• LDA

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

LDA is INTEGER, the leading dimension of the array A, and she must satisfy LDA >= max(1,N). no negotiating on that one ⭐

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• I1

!>          I1 is INTEGER
!>          Index of the first row to swap
!>

I1 is INTEGER — the index of the first row to swap 🌈

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• I2

!>          I2 is INTEGER
!>          Index of the second row to swap
!>

I2 is INTEGER — the index of the second row to swap. her and I1 are a package deal, you can't have one without the other 🎀

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🍓 Author

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

the whole squad behind this, we stan 💜

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Definition at line 99 of file ssyswapr.f. line ninety-nine, iconic number, no notes 🧚

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💜 Author

Generated automatically by Doxygen for LAPACK from the source code. not a human, not a bot bestie exactly, just Doxygen doing her little autogenerated thing ✨

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heads up: this page was auto-generated by Doxygen from the source code, so if something looks weird, blame the generator, not the queens at Univ. of Tennessee, Berkeley, Colorado Denver, and NAG Ltd. 💖

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okay that's the whole page, mwah 💋 — LAPACK Version 3.12.0, from /home/abui.../ssyswapr.f(3), and that's the sign-off bestie, love u, go swap some rows 🫶