SRC/csyconvf.f(3)

💖 NAME

SRC/csyconvf.f — that's the page name, bestie, and this one lives in the Library Functions Manual. We're folding the manual name in right here so the vibe check is complete. ✨

✨ SYNOPSIS

Functions/Subroutines

subroutine csyconvf (uplo, way, n, a, lda, e, ipiv, info)
    CSYCONVF

🧚 Function/Subroutine Documentation

subroutine csyconvf (character uplo, character way, integer n, complex,
       dimension( lda, * ) a, integer lda, complex, dimension( * ) e, integer,
       dimension( * ) ipiv, integer info)
       CSYCONVF

🎀 Purpose

Okay so here's the tea for WAY = 'C', bestie: CSYCONVF converts the factorization output format used in CSYTRF — the one provided on entry in parameter A — into the factorization output format used in CSYTRF_RK (or CSYTRF_BK) that is stored on exit in parameters A and E. It also converts, in place, details of the interchanges stored in IPIV from the format used in CSYTRF into the format used in CSYTRF_RK (or CSYTRF_BK). Iconic behavior, no cap. 💅

If parameter WAY = 'R', CSYCONVF performs the conversion in the reverse direction, i.e. it converts the factorization output format used in CSYTRF_RK (or CSYTRF_BK) provided on entry in parameters A and E into the factorization output format used in CSYTRF that is stored on exit in parameter A. It also converts, in place, details of the interchanges stored in IPIV from the format used in CSYTRF_RK (or CSYTRF_BK) into the format used in CSYTRF. Reversible queen. 🦋

CSYCONVF can also convert in Hermitian matrix case, i.e. between formats used in CHETRF and CHETRF_RK (or CHETRF_BK). Versatile much? 🌈

🌸 Parameters

Every parameter, served fresh, zero skips. 🍓

UPLO

UPLO is CHARACTER*1. It specifies whether the details of the factorization are stored as an upper or lower triangular matrix A.

• = 'U': Upper triangular
• = 'L': Lower triangular

WAY

WAY is CHARACTER*1.

• = 'C': Convert
• = 'R': Revert

N

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

A

A is COMPLEX array, dimension (LDA,N).

1) If WAY ='C: (yes, the source has that exact spacing, we're keeping it)

• On entry, contains factorization details in format used in CSYTRF:
  • a) all elements of the symmetric block diagonal matrix D on the diagonal of A and on superdiagonal (or subdiagonal) of A, and
  • b) If UPLO = 'U': multipliers used to obtain factor U in the superdiagonal part of A. If UPLO = 'L': multipliers used to obtain factor L in the superdiagonal part of A.
• On exit, contains factorization details in format used in CSYTRF_RK or CSYTRF_BK:
  • a) ONLY diagonal elements of the symmetric block diagonal matrix D on the diagonal of A, i.e. D(k,k) = A(k,k); (superdiagonal (or subdiagonal) elements of D are stored on exit in array E), and
  • b) If UPLO = 'U': factor U in the superdiagonal part of A. If UPLO = 'L': factor L in the subdiagonal part of A.

2) If WAY = 'R':

• On entry, contains factorization details in format used in CSYTRF_RK or CSYTRF_BK:
  • a) ONLY diagonal elements of the symmetric block diagonal matrix D on the diagonal of A, i.e. D(k,k) = A(k,k); (superdiagonal (or subdiagonal) elements of D are stored on exit in array E), and
  • b) If UPLO = 'U': factor U in the superdiagonal part of A. If UPLO = 'L': factor L in the subdiagonal part of A.
• On exit, contains factorization details in format used in CSYTRF:
  • a) all elements of the symmetric block diagonal matrix D on the diagonal of A and on superdiagonal (or subdiagonal) of A, and
  • b) If UPLO = 'U': multipliers used to obtain factor U in the superdiagonal part of A. If UPLO = 'L': multipliers used to obtain factor L in the superdiagonal part of A.

LDA

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

E

E is COMPLEX array, dimension (N).

1) If WAY ='C:

• On entry, just a workspace.
• On exit, contains the superdiagonal (or subdiagonal) elements of the symmetric block diagonal matrix D with 1-by-1 or 2-by-2 diagonal blocks, where If UPLO = 'U': E(i) = D(i-1,i), i=2:N, E(1) is set to 0; If UPLO = 'L': E(i) = D(i+1,i), i=1:N-1, E(N) is set to 0.

2) If WAY = 'R':

• On entry, contains the superdiagonal (or subdiagonal) elements of the symmetric block diagonal matrix D with 1-by-1 or 2-by-2 diagonal blocks, where If UPLO = 'U': E(i) = D(i-1,i),i=2:N, E(1) not referenced; If UPLO = 'L': E(i) = D(i+1,i),i=1:N-1, E(N) not referenced.
• On exit, is not changed

IPIV

IPIV is INTEGER array, dimension (N).

• 1) If WAY ='C: On entry, details of the interchanges and the block structure of D in the format used in CSYTRF. On exit, details of the interchanges and the block structure of D in the format used in CSYTRF_RK ( or CSYTRF_BK).
• 1) If WAY ='R: On entry, details of the interchanges and the block structure of D in the format used in CSYTRF_RK ( or CSYTRF_BK). On exit, details of the interchanges and the block structure of D in the format used in CSYTRF.

yes, both are labeled 1) in the original — we are preserving that exact lore, bestie 💀

INFO

INFO is INTEGER.

• = 0: successful exit
• < 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.

🌈 Contributors

November 2017, Igor Kozachenko, Computer Science Division, University of California, Berkeley

Definition at line 208 of file csyconvf.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

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Okay that's the whole page, bestie — signing off from LAPACK Version 3.12.0 on SRC/csyconvf.f(3). Stay converted, stay iconic. 💅✨🫶