?syconv

Converts a symmetric matrix given by a triangular matrix factorization into two matrices and vice versa.

Syntax

FORTRAN 77:

call ssyconv( uplo, way, n, a, lda, ipiv, work, info )

call dsyconv( uplo, way, n, a, lda, ipiv, work, info )

call csyconv( uplo, way, n, a, lda, ipiv, work, info )

call zsyconv( uplo, way, n, a, lda, ipiv, work, info )

Fortran 95:

call syconv( a[,uplo][,way][,ipiv][,info] )

C:

lapack_int LAPACKE_<?>syconv (int matrix_layout, char uplo, char way, lapack_int n, <datatype> * a, lapack_int lda, const lapack_int * ipiv);

Include Files

  • Fortran: mkl.fi
  • Fortran 95: lapack.f90
  • C: mkl.h

Description

The routine converts matrix A, which results from a triangular matrix factorization, into matrices L and D and vice versa. The routine gets non-diagonalized elements of D returned in the workspace and applies or reverses permutation done with the triangular matrix factorization.

Input Parameters

The data types are given for the Fortran interface. A <datatype> placeholder, if present, is used for the C interface data types in the C interface section above. See C Interface Conventions for the C interface principal conventions and type definitions.

uplo

CHARACTER*1. Must be 'U' or 'L'.

Indicates whether the details of the factorization are stored as an upper or lower triangular matrix:

If uplo = 'U': the upper triangular, A = U*D*UT.

If uplo = 'L': the lower triangular, A = L*D*LT.

way

CHARACTER*1. Must be 'C' or 'R'.

Indicates whether the routine converts or reverts the matrix:

way = 'C' means conversion.

way = 'R' means reversion.

n

INTEGER. The order of matrix A; n 0.

a

REAL for ssyconv

DOUBLE PRECISION for dsyconv

COMPLEX for csyconv

DOUBLE COMPLEX for zsyconv

Array of DIMENSION (lda,n).

The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ?sytrf.

lda

INTEGER. The leading dimension of a; lda max(1, n).

ipiv

INTEGER. Array, DIMENSION at least max(1, n).

Details of the interchanges and the block structure of D, as returned by ?sytrf.

work

INTEGER. Workspace array, DIMENSION at least max(1, n).

Output Parameters

info

INTEGER. If info = 0, the execution is successful.

If info < 0, the i-th parameter had an illegal value.

Fortran 95 Interface Notes

Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see Fortran 95 Interface Conventions.

Specific details for the routine syconv interface are as follows:

a

Holds the matrix A of size (n, n).

uplo

Must be 'U' or 'L'.

way

Must be 'C' or 'R'.

ipiv

Holds the vector of length n.

For more complete information about compiler optimizations, see our Optimization Notice.