1DTRTI2(1)                LAPACK routine (version 3.1)                DTRTI2(1)
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NAME

6       DTRTI2 - the inverse of a real upper or lower triangular matrix
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SYNOPSIS

9       SUBROUTINE DTRTI2( UPLO, DIAG, N, A, LDA, INFO )
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11           CHARACTER      DIAG, UPLO
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13           INTEGER        INFO, LDA, N
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15           DOUBLE         PRECISION A( LDA, * )
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PURPOSE

18       DTRTI2 computes the inverse of a real upper or lower triangular matrix.
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20       This is the Level 2 BLAS version of the algorithm.
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ARGUMENTS

24       UPLO    (input) CHARACTER*1
25               Specifies whether the matrix A is upper or lower triangular.  =
26               'U':  Upper triangular
27               = 'L':  Lower triangular
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29       DIAG    (input) CHARACTER*1
30               Specifies whether or not the matrix A is  unit  triangular.   =
31               'N':  Non-unit triangular
32               = 'U':  Unit triangular
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34       N       (input) INTEGER
35               The order of the matrix A.  N >= 0.
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37       A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
38               On  entry, the triangular matrix A.  If UPLO = 'U', the leading
39               n by n upper triangular part of the array A contains the  upper
40               triangular  matrix, and the strictly lower triangular part of A
41               is not referenced.  If UPLO = 'L', the leading  n  by  n  lower
42               triangular  part  of  the array A contains the lower triangular
43               matrix, and the strictly upper triangular part of A is not ref‐
44               erenced.   If  DIAG  = 'U', the diagonal elements of A are also
45               not referenced and are assumed to be 1.
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47               On exit, the (triangular) inverse of the  original  matrix,  in
48               the same storage format.
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50       LDA     (input) INTEGER
51               The leading dimension of the array A.  LDA >= max(1,N).
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53       INFO    (output) INTEGER
54               = 0: successful exit
55               < 0: if INFO = -k, the k-th argument had an illegal value
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59 LAPACK routine (version 3.1)    November 2006                       DTRTI2(1)
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