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

  November 2017,  Igor Kozachenko,


                  Computer Science Division,


                  University of California, Berkeley