SRC/ssyconvf_rook.f(3)

okay so this is the SRC/ssyconvf_rook.f(3) page from the Library Functions Manual, and ngl it's giving linear-algebra format-shifter main character energy. We're converting symmetric factorization output between SSYTRF_ROOK and SSYTRF_RK / SSYTRF_BK vibes, and the IPIV format stays the same. Let's get into it bestie 💅✨

🎀 NAME 🎀

SRC/ssyconvf_rook.f

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

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

This one is SSYCONVF_ROOK, periodt. 👑

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🦋 Function/Subroutine Documentation 🦋

subroutine ssyconvf_rook (character uplo, character way, integer n, real,
    dimension( lda, * ) a, integer lda, real, dimension( * ) e, integer,
    dimension( * ) ipiv, integer info)

SSYCONVF_ROOK is the icon of this page 👑.

🌸 Purpose 🌸

• If parameter WAY = 'C': SSYCONVF_ROOK converts the factorization output format used in SSYTRF_ROOK provided on entry in parameter A into the factorization output format used in SSYTRF_RK (or SSYTRF_BK) that is stored on exit in parameters A and E. The IPIV format for SSYTRF_ROOK and SSYTRF_RK (or SSYTRF_BK) is the same and is not converted.
• If parameter WAY = 'R': SSYCONVF_ROOK performs the conversion in reverse direction, i.e. converts the factorization output format used in SSYTRF_RK (or SSYTRF_BK) provided on entry in parameters A and E into the factorization output format used in SSYTRF_ROOK that is stored on exit in parameter A. The IPIV format for SSYTRF_ROOK and SSYTRF_RK (or SSYTRF_BK) is the same and is not converted.

💅 Parameters 💅

• UPLO — UPLO is CHARACTER*1. 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 REAL array, dimension (LDA,N).
  • 1) If WAY ='C': On entry, contains factorization details in format used in SSYTRF_ROOK:
    • 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 SSYTRF_RK or SSYTRF_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 SSYTRF_RK or SSYTRF_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 SSYTRF_ROOK:
    • 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 REAL 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).
  • On entry, details of the interchanges and the block structure of D as determined:
    1. by SSYTRF_ROOK, if WAY ='C';
    2. by SSYTRF_RK (or SSYTRF_BK), if WAY ='R'.
  • The IPIV format is the same for all these routines.
  • On exit, is not changed.
• 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 196 of file ssyconvf_rook.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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okay bestie, that's the whole page! This footer situation is SRC/ssyconvf_rook.f(3) and LAPACK Version 3.12.0 — no cap, she ate. Byeee 💖🦋✨