Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?trti2
Computes the inverse of a triangular matrix (unblocked algorithm).
Syntax
call strti2(uplo, diag, n, a, lda, info)
call dtrti2(uplo, diag, n, a, lda, info)
call ctrti2(uplo, diag, n, a, lda, info)
call ztrti2(uplo, diag, n, a, lda, info)
Include Files
mkl.fi
Description
The routine ?trti2 computes the inverse of a real/complex upper or lower triangular matrix.
This is the Level 2 BLAS version of the algorithm.
Input Parameters
- uplo
-
CHARACTER*1 . Specifies whether the matrix A is upper or lower triangular. = ‘U’ : upper triangular = ‘L’ : lower triangular
- diag
-
CHARACTER*1 . Specifies whether or not the matrix A is unit triangular. = ‘N’ : non-unit triangular = ‘N’ : non-unit triangular
- n
-
INTEGER. Specifies the order of the matrix A. The value of n must be at least zero.
- a
-
REAL for strti2 DOUBLE PRECISION for dtrti2 COMPLEX for ctrti2 DOUBLE COMPLEX for ztrti2 . Array, DIMENSION ( lda , n ). On entry, the triangular matrix A . If uplo = 'U' , the leading n -by- n upper triangular part of the array a contains the upper triangular matrix, and the strictly lower triangular part of a is not referenced. If uplo = 'L' , the leading n -by- n lower triangular part of the array a contains the lower triangular matrix, and the strictly upper triangular part of a is not referenced. If diag = 'U' , the diagonal elements of a are also not referenced and are assumed to be 1.
- lda
-
INTEGER . The leading dimension of the array a . lda≥ max(1,n) .
Output Parameters
- a
-
On exit, the (triangular) inverse of the original matrix, in the same storage format.
info
INTEGER .
= 0 : successful exit
< 0 : if info = -k , the k -th argument had an illegal value