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.

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

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Univ. of California Berkeley

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NAG Ltd.

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