?tftri

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 12/16/2022

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?tftri

Computes the inverse of a triangular matrix stored in the Rectangular Full Packed (RFP) format.

Syntax

lapack_int LAPACKE_stftri (int matrix_layout , char transr , char uplo , char diag , lapack_int n , float * a );

lapack_int LAPACKE_dtftri (int matrix_layout , char transr , char uplo , char diag , lapack_int n , double * a );

lapack_int LAPACKE_ctftri (int matrix_layout , char transr , char uplo , char diag , lapack_int n , lapack_complex_float * a );

lapack_int LAPACKE_ztftri (int matrix_layout , char transr , char uplo , char diag , lapack_int n , lapack_complex_double * a );

Include Files

mkl.h

Description

Computes the inverse of a triangular matrix A stored in the Rectangular Full Packed (RFP) format. For the description of the RFP format, see Matrix Storage Schemes.

This is the block version of the algorithm, calling Level 3 BLAS.

Input Parameters

matrix_layout	Specifies whether matrix storage layout is row major (LAPACK_ROW_MAJOR) or column major (LAPACK_COL_MAJOR).
transr	Must be 'N', 'T' (for real data) or 'C' (for complex data). If transr = 'N', the Normal transr of RFP `A` is stored. If transr = 'T', the Transpose transr of RFP `A` is stored. If transr = 'C', the Conjugate-Transpose transr of RFP `A` is stored.
uplo	Must be 'U' or 'L'. Indicates whether the upper or lower triangular part of RFP `A` is stored: If uplo = 'U', the array a stores the upper triangular part of the matrix `A`. If uplo = 'L', the array a stores the lower triangular part of the matrix `A`.
diag	Must be 'N' or 'U'. If `diag = 'N'`, then `A` is not a unit triangular matrix. If `diag = 'U'`, `A` is unit triangular: diagonal elements of `A` are assumed to be 1 and not referenced in the array `a`.
n	The order of the matrix `A`; n≥ 0.
a	Array, size max(1, n*(n + 1)/2). The array a contains the matrix `A` in the RFP format.

Output Parameters

a	The (triangular) inverse of the original matrix in the same storage format.

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, A_{i, i} is exactly zero. The triangular matrix is singular and its inverse cannot be computed.

Parent topic: Matrix Inversion: LAPACK Computational Routines

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