ssyconvf.f(3)

NAME
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 coverts in place details of
     the intechanges 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 coverts in place details of
     the intechanges 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.

Date:
    November 2017

Contributors:

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

Definition at line 208 of file ssyconvf.f.

Author

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