dsyconvf.f(3)

NAME
dsyconvf.f

SYNOPSIS

  Functions/Subroutines
subroutine dsyconvf (UPLO, WAY, N, A, LDA, E, IPIV, INFO)
DSYCONVF

Function/Subroutine Documentation

  subroutine dsyconvf (character UPLO, character WAY, integer N, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( * ) E, integer, dimension( * ) IPIV, integer INFO)

Purpose:

     If parameter WAY = 'C':
     DSYCONVF converts the factorization output format used in
     DSYTRF provided on entry in parameter A into the factorization
     output format used in DSYTRF_RK (or DSYTRF_BK) that is stored
     on exit in parameters A and E. It also converts in place details of
     the intechanges stored in IPIV from the format used in DSYTRF into
     the format used in DSYTRF_RK (or DSYTRF_BK).
     If parameter WAY = 'R':
     DSYCONVF performs the conversion in reverse direction, i.e.
     converts the factorization output format used in DSYTRF_RK
     (or DSYTRF_BK) provided on entry in parameters A and E into
     the factorization output format used in DSYTRF that is stored
     on exit in parameter A. It also converts in place details of
     the intechanges stored in IPIV from the format used in DSYTRF_RK
     (or DSYTRF_BK) into the format used in DSYTRF.

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 DOUBLE PRECISION array, dimension (LDA,N)
              1) If WAY ='C':
              On entry, contains factorization details in format used in
              DSYTRF:
                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
              DSYTRF_RK or DSYTRF_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
              DSYTRF_RK or DSYTRF_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
              DSYTRF:
                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 DOUBLE PRECISION 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 DSYTRF.
              On exit, details of the interchanges and the block
              structure of D in the format used in DSYTRF_RK
              ( or DSYTRF_BK).
              1) If WAY ='R':
              On entry, details of the interchanges and the block
              structure of D in the format used in DSYTRF_RK
              ( or DSYTRF_BK).
              On exit, details of the interchanges and the block
              structure of D in the format used in DSYTRF.

    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 dsyconvf.f.

Author

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