If parameter WAY = 'C':


 DSYCONVF_ROOK converts the factorization output format used in


 DSYTRF_ROOK 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. IPIV format for DSYTRF_ROOK and


 DSYTRF_RK (or DSYTRF_BK) is the same and is not converted.


 If parameter WAY = 'R':


 DSYCONVF_ROOK 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_ROOK that is stored


 on exit in parameter A. IPIV format for DSYTRF_ROOK and


 DSYTRF_RK (or DSYTRF_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 DOUBLE PRECISION array, dimension (LDA,N)


          1) If WAY ='C':


          On entry, contains factorization details in format used in


          DSYTRF_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


          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_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 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)


          On entry, details of the interchanges and the block


          structure of D as determined:


          1) by DSYTRF_ROOK, if WAY ='C';


          2) by DSYTRF_RK (or DSYTRF_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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

  November 2017,  Igor Kozachenko,


                  Computer Science Division,


                  University of California, Berkeley