# csyconvf.f man page

csyconvf.f

## Synopsis

### Functions/Subroutines

subroutine **csyconvf** (UPLO, WAY, **N**, A, **LDA**, E, IPIV, INFO)**CSYCONVF**

## Function/Subroutine Documentation

### subroutine csyconvf (character UPLO, character WAY, integer N, complex, dimension( lda, * ) A, integer LDA, complex, dimension( * ) E, integer, dimension( * ) IPIV, integer INFO)

**CSYCONVF**

**Purpose:**

If parameter WAY = 'C': CSYCONVF converts the factorization output format used in CSYTRF provided on entry in parameter A into the factorization output format used in CSYTRF_RK (or CSYTRF_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 CSYTRF into the format used in CSYTRF_RK (or CSYTRF_BK). If parameter WAY = 'R': CSYCONVF performs the conversion in reverse direction, i.e. converts the factorization output format used in CSYTRF_RK (or CSYTRF_BK) provided on entry in parameters A and E into the factorization output format used in CSYTRF 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 CSYTRF_RK (or CSYTRF_BK) into the format used in CSYTRF. CSYCONVF can also convert in Hermitian matrix case, i.e. between formats used in CHETRF and CHETRF_RK (or CHETRF_BK).

**Parameters:***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 COMPLEX array, dimension (LDA,N) 1) If WAY ='C': On entry, contains factorization details in format used in CSYTRF: 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 CSYTRF_RK or CSYTRF_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 CSYTRF_RK or CSYTRF_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 CSYTRF: 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 COMPLEX 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 CSYTRF. On exit, details of the interchanges and the block structure of D in the format used in CSYTRF_RK ( or CSYTRF_BK). 1) If WAY ='R': On entry, details of the interchanges and the block structure of D in the format used in CSYTRF_RK ( or CSYTRF_BK). On exit, details of the interchanges and the block structure of D in the format used in CSYTRF.

*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.

**Date:**November 2017

**Contributors:**

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

Definition at line 211 of file csyconvf.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page csyconvf(3) is an alias of csyconvf.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK