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ssyconvf_rook.f(3) LAPACK ssyconvf_rook.f(3)

NAME

ssyconvf_rook.f

SYNOPSIS

Functions/Subroutines


subroutine ssyconvf_rook (UPLO, WAY, N, A, LDA, E, IPIV, INFO)
SSYCONVF_ROOK

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

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. 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. 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

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2017

Contributors:


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

Definition at line 199 of file ssyconvf_rook.f.

Author

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Tue Nov 14 2017 Version 3.8.0