Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3 - solves a triangular system of the form   A * X = B or A**T * X = B,

SYNOPSIS

       SUBROUTINE DTRTRS( UPLO, TRANS, DIAG, N, NRHS, A, LDA, B, LDB, INFO )

           CHARACTER      DIAG, TRANS, UPLO

           INTEGER        INFO, LDA, LDB, N, NRHS

           DOUBLE         PRECISION A( LDA, * ), B( LDB, * )

PURPOSE

       DTRTRS solves a triangular system of the form
        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.

ARGUMENTS

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

        TRANS   (input) 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    (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.

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

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

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

        LDB     (input) INTEGER
                The leading dimension of the array B.  LDB >= 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, the i-th diagonal element of A is zero,
                indicating that the matrix is singular and the solutions
                X have not been computed.

 LAPACK routine (version 3.2)               April 2011                            DTRTRS(3lapack)