?sytri2x

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 3/22/2024

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?sytri2x

Computes the inverse of a symmetric indefinite matrix after ?sytri2allocates memory.

Syntax

lapack_int LAPACKE_ssytri2x (int matrix_layout , char uplo , lapack_int n , float * a , lapack_int lda , const lapack_int * ipiv , lapack_int nb );

lapack_int LAPACKE_dsytri2x (int matrix_layout , char uplo , lapack_int n , double * a , lapack_int lda , const lapack_int * ipiv , lapack_int nb );

lapack_int LAPACKE_csytri2x (int matrix_layout , char uplo , lapack_int n , lapack_complex_float * a , lapack_int lda , const lapack_int * ipiv , lapack_int nb );

lapack_int LAPACKE_zsytri2x (int matrix_layout , char uplo , lapack_int n , lapack_complex_double * a , lapack_int lda , const lapack_int * ipiv , lapack_int nb );

Include Files

mkl.h

Description

The routine computes the inverse inv(A) of a symmetric indefinite matrix A using the factorization A = U*D*U^T or A = L*D*L^T computed by ?sytrf.

The ?sytri2x actually computes the inverse after the ?sytri2 routine allocates memory before calling ?sytri2x.

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 = UDU^T`. If `uplo = 'L'`, the array `a` stores the factorization `A = LDL^T`.
n	The order of the matrix `A`; `n≥ 0`.
a	Array 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 ?sytrf. The second dimension of a must be at least `max(1,n)`.
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 ?sytrf.
nb	Block size.

Output Parameters

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.

Parent topic: Matrix Inversion: LAPACK Computational Routines

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Developer Reference for Intel® oneAPI Math Kernel Library for C

?sytri2x

Syntax

Include Files

Description

Input Parameters

Output Parameters

Return Values

See Also