• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

ctrtri - compute the inverse of a complex upper or lower triangular matrix A

SYNOPSIS

  SUBROUTINE CTRTRI( UPLO, DIAG, N, A, LDA, INFO)
  CHARACTER * 1 UPLO, DIAG
  COMPLEX A(LDA,*)
  INTEGER N, LDA, INFO

  SUBROUTINE CTRTRI_64( UPLO, DIAG, N, A, LDA, INFO)
  CHARACTER * 1 UPLO, DIAG
  COMPLEX A(LDA,*)
  INTEGER*8 N, LDA, INFO

F95 INTERFACE

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

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

C INTERFACE

#include <sunperf.h>

void ctrtri(char uplo, char diag, int n, complex *a, int lda, int *info);

void ctrtri_64(char uplo, char diag, long n, complex *a, long lda, long *info);

PURPOSE

ctrtri computes the inverse of a complex upper or lower triangular matrix A.

This is the Level 3 BLAS version of the algorithm.

ARGUMENTS

• 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.