NAME

       dtrtrs.f -

SYNOPSIS

   Functions/Subroutines
       subroutine dtrtrs (UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB, INFO)
           DTRTRS

Function/Subroutine Documentation

   subroutine dtrtrs (characterUPLO, characterTRANS, characterDIAG, integerN, integerNRHS, double
       precision, dimension( lda, * )A, integerLDA, double precision, dimension( ldb, * )B,
       integerLDB, integerINFO)
       DTRTRS

       Purpose:

            DTRTRS solves a triangular system of the form

               A * X = B  or  A**T * X = B,

            where A is a triangular matrix of order N, and B is an N-by-NRHS
            matrix.  A check is made to verify that A is nonsingular.

       Parameters:
           UPLO

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

           TRANS

                     TRANS is CHARACTER*1
                     Specifies the form of the system of equations:
                     = 'N':  A * X = B  (No transpose)
                     = 'T':  A**T * X = B  (Transpose)
                     = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

           DIAG

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

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           NRHS

                     NRHS is INTEGER
                     The number of right hand sides, i.e., the number of columns
                     of the matrix B.  NRHS >= 0.

           A

                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     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.

           LDA

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

           B

                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     On entry, the right hand side matrix B.
                     On exit, if INFO = 0, the solution matrix X.

           LDB

                     LDB is INTEGER
                     The leading dimension of the array B.  LDB >= max(1,N).

           INFO

                     INFO is INTEGER
                     = 0:  successful exit
                     < 0: if INFO = -i, the i-th argument had an illegal value
                     > 0: if INFO = i, the i-th diagonal element of A is zero,
                          indicating that the matrix is singular and the solutions
                          X have not been computed.

       Author:
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Date:
           November 2011

       Definition at line 140 of file dtrtrs.f.

Author

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