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.

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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

December 2016

  December 2016,  Igor Kozachenko,
                  Computer Science Division,
                  University of California, Berkeley