SRC/zhetrs2.f(3)

💅 SRC/zhetrs2.f(3) — Library Functions Manual 🎀

okay bestie, welcome to the <pink>Library Functions Manual</pink> ✨ this page is literally all about SRC/zhetrs2.f and honestly? she's iconic. let's get into it 🫶

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines

• subroutine zhetrs2 (uplo, n, nrhs, a, lda, ipiv, b, ldb, work, info) — that's her! ZHETRS2 💖

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🦋 Function/Subroutine Documentation 🦋

💫 the signature (verbatim, no cap)

subroutine zhetrs2 (character uplo, integer n, integer nrhs, complex*16,
    dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv,
    complex*16, dimension( ldb, * ) b, integer ldb, complex*16, dimension( *
    ) work, integer info)

ZHETRS2 🔥

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🎯 Purpose:

!>
!> ZHETRS2 solves a system of linear equations A*X = B with a complex
!> Hermitian matrix A using the factorization A = U*D*U**H or
!> A = L*D*L**H computed by ZHETRF and converted by ZSYCONV.
!>

so basically: give her a system of linear equations A*X = B, where A is a complex Hermitian matrix, and she will solve it. the factorization she expects is A = U*D*U**H or A = L*D*L**H — the one ZHETRF computed and ZSYCONV converted. periodt 💅

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🧚 Parameters (all of them, every single one, no cutting corners)

• 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**H;
!>          = 'L':  Lower triangular, form is A = L*D*L**H.
!>

<cyan>CHARACTER*1</cyan> energy 🌈 she decides whether the factorization details are stored as an upper or lower triangular matrix:

• 'U' — upper triangular, form is A = U*D*U**H ⭐
• 'L' — lower triangular, form is A = L*D*L**H 💜

• N

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

<cyan>INTEGER</cyan>, the order of the matrix A. constraint: N >= 0 🍓

• NRHS

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

<cyan>INTEGER</cyan>, the number of right hand sides — aka how many columns the matrix B has. constraint: NRHS >= 0 ✨

• A

!>          A is COMPLEX*16 array, dimension (LDA,N)
!>          The block diagonal matrix D and the multipliers used to
!>          obtain the factor U or L as computed by ZHETRF.
!>

<cyan>COMPLEX*16</cyan> 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 ZHETRF 👑

• LDA

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

<cyan>INTEGER</cyan>, the leading dimension of the array A. constraint: LDA >= max(1,N) 🎀

• IPIV

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

<cyan>INTEGER</cyan> array, dimension (N) — the deets on the interchanges and the block structure of D, as determined by ZHETRF 🌸

• B

!>          B is COMPLEX*16 array, dimension (LDB,NRHS)
!>          On entry, the right hand side matrix B.
!>          On exit, the solution matrix X.
!>

<cyan>COMPLEX*16</cyan> array, dimension (LDB,NRHS). on entry it's the right hand side matrix B; on exit it's the solution matrix X. glow-up fr fr ✨

• LDB

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

<cyan>INTEGER</cyan>, the leading dimension of the array B. constraint: LDB >= max(1,N) 🦋

• WORK

!>          WORK is COMPLEX*16 array, dimension (N)
!>

<cyan>COMPLEX*16</cyan> array, dimension (N). she works hard so you don't have to 💅

• INFO

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

<cyan>INTEGER</cyan>, the vibe check report:

• = 0 — successful exit, we ate 🎉
• < 0 — if INFO = -i, the i-th argument had an illegal value 😭

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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 🫶

Definition at line 125 of file zhetrs2.f. ⭐

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📝 Author (again, yes really)

Generated automatically by Doxygen for LAPACK from the source code. 🤖✨

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ngl bestie, if your INFO comes back negative it's giving "one of your arguments is illegal" — go check the exact one at index i and fix it before you come for her 💀

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LAPACK · Version 3.12.0 · SRC/zhetrs2.f(3) — mwah, that's the whole page, ily, go solve those Hermitian systems 💖🎀🦋🌈👑