SRC/ssyconvf.f(3)

NAME
SRC/ssyconvf.f

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

Purpose:

    !> 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
    !>          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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