?syconv

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 4/28/2026

Version

Public

?syconv

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

Syntax

lapack_intLAPACKE_ssyconv ( intmatrix_layout , charuplo , charway , lapack_intn , float*a , lapack_intlda , constlapack_int*ipiv , float*e );

lapack_intLAPACKE_dsyconv ( intmatrix_layout , charuplo , charway , lapack_intn , double*a , lapack_intlda , constlapack_int*ipiv , double*e );

lapack_intLAPACKE_csyconv ( intmatrix_layout , charuplo , charway , lapack_intn , lapack_complex_float*a , lapack_intlda , constlapack_int*ipiv , lapack_complex_float*e );

lapack_intLAPACKE_zsyconv ( intmatrix_layout , charuplo , charway , lapack_intn , lapack_complex_double*a , lapack_intlda , constlapack_int*ipiv , lapack_complex_double*e );

Include Files

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 returns non-diagonalized elements of D and applies or reverses permutation done with the triangular matrix factorization.

Input Parameters

matrix_layout: Specifies whether matrix storage layout is row major ( LAPACK_ROW_MAJOR ) or column major ( LAPACK_COL_MAJOR ).

uplo

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*U^{T} . If uplo = 'L' : the lower triangular, A = L*D*L^{T} .

way

Must be ‘C’ or ‘R’ .

n

The order of matrix A ; n ≥ 0.

a

REAL for ssyconv DOUBLE PRECISION for dsyconv COMPLEX for csyconv DOUBLE COMPLEX for zsyconv

Array of size max(1, lda * n ) .

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

lda

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

ipiv

Array, size at least max(1, n) .

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

Output Parameters

e: REAL for ssyconv DOUBLE PRECISION for dsyconv COMPLEX for csyconv DOUBLE COMPLEX for zsyconv Array of size max(1, n) containing the superdiagonal/subdiagonal of the symmetric 1-by-1 or 2-by-2 block diagonal matrix D in L*D*L^T .

Return Values

info: If info = 0 , the execution is successful. If info < 0 , the i -th parameter had an illegal value. If info = -1011 , memory allocation error occurred.

LAPACK 95 Interface Notes

There exist FORTRAN 77 and FORTRAN 95 interfaces for this routine. See the Intel® oneMKL Fortran Developer Reference for details.

NOTE:

?sytrf

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Developer Reference for Intel® oneAPI Math Kernel Library for C

?syconv

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values

LAPACK 95 Interface Notes