?sytri2

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 12/16/2022

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?sytri2

Computes the inverse of a symmetric indefinite matrix through allocating memory and calling ?sytri2x.

Syntax

lapack_int LAPACKE_ssytri2 (int matrix_layout , char uplo , lapack_int n , float * a , lapack_int lda , const lapack_int * ipiv );

lapack_int LAPACKE_dsytri2 (int matrix_layout , char uplo , lapack_int n , double * a , lapack_int lda , const lapack_int * ipiv );

lapack_int LAPACKE_csytri2 (int matrix_layout , char uplo , lapack_int n , lapack_complex_float * a , lapack_int lda , const lapack_int * ipiv );

lapack_int LAPACKE_zsytri2 (int matrix_layout , char uplo , lapack_int n , lapack_complex_double * a , lapack_int lda , const lapack_int * ipiv );

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 ?sytri2 routine allocates a temporary buffer before calling ?sytri2x that actually computes the inverse.

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 block diagonal matrix `D` and the multipliers used to obtain the factor U or L as returned 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

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

If uplo = 'U', the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced.

If uplo = '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, the i-th parameter had an illegal value.

If info = i, D(i,i) = 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

?sytri2

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