functiondtrtri

Information

Lapack documentation:

   Purpose
   =======

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

   This is the Level 3 BLAS version of the algorithm.

   Arguments
   =========

   UPLO    (input) CHARACTER*1
           = 'U':  A is upper triangular;
           = 'L':  A is lower triangular.

   DIAG    (input) CHARACTER*1
           = 'N':  A is non-unit triangular;
           = 'U':  A is unit triangular.

   N       (input) INTEGER
           The order of the matrix A.  N >= 0.

   A       (input/output) DOUBLE PRECISION 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.
           On exit, the (triangular) inverse of the original matrix, in
           the same storage format.

   LDA     (input) INTEGER
           The leading dimension of the array A.  LDA >= max(1,N).

   INFO    (output) INTEGER
           = 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.

   =====================================================================

Inputs

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