?hetrs_rook

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

?hetrs_rook

Solves a system of linear equations with a UDU- or LDL-factored Hermitian coefficient matrix.

Syntax

call chetrs_rook ( uplo , n , nrhs , a , lda , ipiv , b , ldb , info )

call zhetrs_rook ( uplo , n , nrhs , a , lda , ipiv , b , ldb , info )

call hetrs_rook ( a , b , ipiv [ , uplo ] [ , info ] )

Include Files

mkl.fi , mkl_lapack.f90

Description

chetrs_rook zhetrs_rook hetrs_rook

The routine solves for a system of linear equations A*X = B with a complex Hermitian matrix A using the factorization A = U*D*U^{H} or A = L*D*L^{H} computed by ?hetrf_rook (Computes the bounded Bunch-Kaufman factorization of a complex Hermitian matrix.) .

Input Parameters

uplo

CHARACTER*1 . Must be ‘U’ or ‘L’ .

Indicates how the input matrix A has been factored:

If uplo = 'U' , the factorization is of the form A = U*D*U^{H} .

If uplo = 'L' , the factorization is of the form A = L*D*L^{H} .

n

INTEGER . The order of matrix A ; n ≥ 0.

nrhs

INTEGER . The number of right-hand sides; nrhs ≥ 0.

ipiv

INTEGER .

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

The ipiv array, as returned by ?hetrf_rook (Computes the bounded Bunch-Kaufman factorization of a complex Hermitian matrix.) .

a , b

COMPLEX for chetrs_rook

DOUBLE COMPLEX for zhetrs_rook .

Arrays: a(lda,n) , b(ldb,nrhs) .

The array a contains the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ?hetrf_rook (Computes the bounded Bunch-Kaufman factorization of a complex Hermitian matrix.) (see uplo ).

The array b contains the matrix B whose columns are the right-hand sides for the system of equations.

lda

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

ldb

INTEGER . The leading dimension of b ; ldb≥ max(1, n) .

Output Parameters

b

Overwritten by the solution matrix X .

info

INTEGER .

If info=0 , the execution is successful.
If info = -i , the i- th parameter had an illegal value.

Return Values

No return value, info is an Output Parameter.

LAPACK 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 LAPACK 95 Interface Conventions .

Specific details for the routine hetrs_rook interface are as follows:

a

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

b

Holds the matrix B of size ( n , nrhs ).

ipiv

Holds the vector of length n .

uplo

Must be ‘U’ or ‘L’ . The default value is ‘U’ .

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?hetrs_rook

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values

LAPACK 95 Interface Notes