p?trtri

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

p?trtri

Computes the inverse of a triangular distributed matrix.

Syntax

call pstrtri ( uplo , diag , n , a , ia , ja , desca , info )

call pdtrtri ( uplo , diag , n , a , ia , ja , desca , info )

call pctrtri ( uplo , diag , n , a , ia , ja , desca , info )

call pztrtri ( uplo , diag , n , a , ia , ja , desca , info )

Include Files

mkl_scalapack.h

Description

pstrtri pdtrtri pctrtri pztrtri The p?trtri routine function computes the inverse of a real or complex upper or lower triangular distributed matrix sub( A ) = A ( ia : ia + n -1, ja : ja + n -1).

Input Parameters

uplo

(global) CHARACTER*1 . Must be ‘U’ or ‘L’ .

Specifies whether the distributed matrix sub( A ) is upper or lower triangular. If uplo = 'U' , sub( A ) is upper triangular. If uplo = 'L' , sub( A ) is lower triangular.

diag

CHARACTER*1 . Must be ‘N’ or ‘U’ .

Specifies whether or not the distributed matrix sub( A ) is unit triangular. If diag = 'N' , then sub( A ) is non-unit triangular. If diag = 'U' , then sub( A ) is unit triangular.

n

(global) INTEGER . The number of rows and columns to be operated on, that is, the order of the distributed matrix sub( A ) (n≥0) .

a

(local) REAL for pstrtri DOUBLE PRECISION for pdtrtri COMPLEX for pctrtri DOUBLE COMPLEX for pztrtri .

Pointer into the local memory to an array of local size (lld_a,LOCc(ja+n-1)) .

The array a contains the local pieces of the triangular distributed matrix sub( A ). If uplo = 'U' , the leading n -by- n upper triangular part of sub( A ) contains the upper triangular matrix to be inverted, and the strictly lower triangular part of sub( A ) is not referenced. If uplo = 'L' , the leading n -by- n lower triangular part of sub( A ) contains the lower triangular matrix, and the strictly upper triangular part of sub( A ) is not referenced.

ia , ja

(global) INTEGER . The row and column indices in the global matrix A indicating the first row and the first column of the matrix sub( A ), respectively.

desca

(global and local) INTEGER array of size dlen_ . The array descriptor for the distributed matrix A .

Output Parameters

a: On exit, overwritten by the (triangular) inverse of the original matrix.

info

(global) INTEGER . If info=0 , the execution is successful.

info < 0 :

If the i -th argument is an array and the j- th entry had an illegal value, then info = -( i *100+ j ); if the i- th argument is a scalar and had an illegal value, then info = -i .

info> 0 :

If info = k , A ( ia + k -1, ja + k -1) is exactly zero. The triangular matrix sub( A ) is singular and its inverse cannot be computed.

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?trtri

Syntax

Include Files

Description

Input Parameters

Output Parameters