NAME

strtri - compute the inverse of a real upper or lower triangular matrix A

SYNOPSIS

  SUBROUTINE STRTRI( UPLO, DIAG, N, A, LDA, INFO)
  CHARACTER * 1 UPLO, DIAG
  INTEGER N, LDA, INFO
  REAL A(LDA,*)

  SUBROUTINE STRTRI_64( UPLO, DIAG, N, A, LDA, INFO)
  CHARACTER * 1 UPLO, DIAG
  INTEGER*8 N, LDA, INFO
  REAL A(LDA,*)

  SUBROUTINE TRTRI( UPLO, DIAG, [N], A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO, DIAG
  INTEGER :: N, LDA, INFO
  REAL, DIMENSION(:,:) :: A

  SUBROUTINE TRTRI_64( UPLO, DIAG, [N], A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO, DIAG
  INTEGER(8) :: N, LDA, INFO
  REAL, DIMENSION(:,:) :: A

#include <sunperf.h>

void strtri(char uplo, char diag, int n, float *a, int lda, int *info);

void strtri_64(char uplo, char diag, long n, float *a, long lda, long *info);

strtri computes the inverse of a real upper or lower triangular matrix A.

This is the Level 3 BLAS version of the algorithm.

UPLO (input)

 = 'U':  A is upper triangular;

 = 'L':  A is lower triangular.

DIAG (input)

 = 'N':  A is non-unit triangular;

 = 'U':  A is unit triangular.

N (input)
The order of the matrix A. N > = 0.
A (input/output)
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. On exit, the (triangular) inverse of the original matrix, in the same storage format.
LDA (input)
The leading dimension of the array A. LDA > = max(1,N).

INFO (output)

 = 0: successful exit

 < 0: if INFO  = -i, the i-th argument had an illegal value

 > 0: if INFO  = i, A(i,i) is exactly zero.  The triangular
matrix is singular and its inverse can not be computed.