SRC/ssyconvf.f(3)

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version 3.12.1 · 5 versions
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🎀 NAME 🎀

Bestie, this page is SRC/ssyconvf.f, and it lives in the Library Functions Manual. The full page-title vibe is SRC/ssyconvf.f(3) — yes, we’re folding that header info in right here. 💅✨

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

  • subroutine ssyconvf (uplo, way, n, a, lda, e, ipiv, info)
  • SSYCONVF

🌸 Function/Subroutine Documentation 🌸

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

SSYCONVF — that’s the icon, periodt. 👑

💅 Purpose 💅

Okay so bestie, here’s the conversion tea. If parameter WAY = 'C': SSYCONVF converts the factorization output format used in SSYTRF 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. It also converts in place details of the interchanges stored in IPIV from the format used in SSYTRF into the format used in SSYTRF_RK (or SSYTRF_BK).

If parameter WAY = 'R': SSYCONVF 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 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 SSYTRF_RK (or SSYTRF_BK) into the format used in SSYTRF.

🌈 Parameters 🌈

💖 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 REAL array, dimension (LDA,N).

1) If WAY ='C':

On entry, contains factorization details in format used in SSYTRF:

  • 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:

  • 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).

1) If WAY ='C': On entry, details of the interchanges and the block structure of D in the format used in SSYTRF. On exit, details of the interchanges and the block structure of D in the format used in SSYTRF_RK ( or SSYTRF_BK).

1) If WAY ='R': On entry, details of the interchanges and the block structure of D in the format used in SSYTRF_RK ( or SSYTRF_BK). On exit, details of the interchanges and the block structure of D in the format used in SSYTRF.

💖 INFO 💖

INFO is INTEGER.

  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value

💖 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 205 of file ssyconvf.f.

🌈 Author 🌈

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