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 . The order of the matrix A . n≥ 0 .
- 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