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## ssyconvf()

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

SSYCONVF

Download SSYCONVF + dependencies [TGZ] [ZIP] [TXT]

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

  [in]

  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
      !>

  [in]

  WAY

      !>          WAY is CHARACTER*1
      !>          = 'C': Convert
      !>          = 'R': Revert
      !>

  [in]

  N

      !>          N is INTEGER
      !>          The order of the matrix A.  N >= 0.
      !>

  [in,out]

  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.
      !>

  [in]

  LDA

      !>          LDA is INTEGER
      !>          The leading dimension of the array A.  LDA >= max(1,N).
      !>

  [in,out]

  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
      !>

  [in,out]

  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.
      !>

  [out]

  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
      !>
      !>