?hetri2x

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 4/28/2026

Version

Public

?hetri2x

Computes the inverse of a Hermitian indefinite matrix after ?hetri2 sets the leading dimension of the workspace allocates memory .

Syntax

lapack_intLAPACKE_chetri2x ( intmatrix_layout , charuplo , lapack_intn , lapack_complex_float*a , lapack_intlda , constlapack_int*ipiv , lapack_intnb );

lapack_intLAPACKE_zhetri2x ( intmatrix_layout , charuplo , lapack_intn , lapack_complex_double*a , lapack_intlda , constlapack_int*ipiv , lapack_intnb );

Include Files

mkl.h

Description

The routine computes the inverse inv(A) of a Hermitian indefinite matrix A using the factorization A = U*D*U^{H} or A = L*D*L^{H} computed by ?hetrf .

The ?hetri2x actually computes the inverse after the ?hetri2 routine sets the leading dimension of the workspace allocates memory before calling ?hetri2x .

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 how the input matrix A has been factored:

If uplo = 'U' , the array a stores the factorization A = U*D*U^{H} .

If uplo = 'L' , the array a stores the factorization A = L*D*L^{H} .

n

The order of the matrix A ; n≥ 0 .

a , work

Arrays:

a ( lda ,*) contains the nb (block size) diagonal matrix D and the multipliers used to obtain the factor U or L as returned by ?hetrf .

work is a workspace array of the dimension (n+nb+1)*(nb+3)

where

nb is the block size as set by ?hetrf .

a

Arrays a (size max(1, lda * n )) contains the nb (block size) diagonal matrix D and the multipliers used to obtain the factor U or L as returned by ?hetrf .

lda

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

ipiv

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

Details of the interchanges and the nb structure of D as returned by ?hetrf .

nb

Block size.

Output Parameters

a

If info = 0, the symmetric inverse of the original matrix.

If info = ‘U’ , the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced.

If info = ‘L’ , the lower triangular part of the inverse is formed and the part of A above the diagonal is not referenced.

Return Values

This function returns a value info .

If info = 0, the execution is successful.
If info = -i , parameter i had an illegal value.
If info = i , D_{ii} = 0; D is singular and its inversion could not be computed.

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:

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Developer Reference for Intel® oneAPI Math Kernel Library for C

?hetri2x

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values

LAPACK 95 Interface Notes