SRC/ctrtrs.f(3)

NAME
SRC/ctrtrs.f

SYNOPSIS

  Functions/Subroutines
subroutine ctrtrs (uplo, trans, diag, n, nrhs, a, lda, b, ldb, info)
CTRTRS

Function/Subroutine Documentation

  subroutine ctrtrs (character uplo, character trans, character diag, integer n, integer nrhs, complex, dimension( lda, * ) a, integer lda, complex, dimension( ldb, * ) b, integer ldb, integer info)

CTRTRS

Purpose:

     CTRTRS solves a triangular system of the form
        A * X = B,  A**T * X = B,  or  A**H * 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)

    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 COMPLEX 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 COMPLEX 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.

Definition at line 138 of file ctrtrs.f.

Author

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