SRC/dgtsv.f(3)

NAME
SRC/dgtsv.f

SYNOPSIS

  Functions/Subroutines
subroutine dgtsv (n, nrhs, dl, d, du, b, ldb, info)
DGTSV computes the solution to system of linear equations A * X = B for GT matrices

Function/Subroutine Documentation

  subroutine dgtsv (integer n, integer nrhs, double precision, dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double precision, dimension( ldb, * ) b, integer ldb, integer info)

DGTSV computes the solution to system of linear equations A * X = B for GT matrices

Purpose:

     DGTSV  solves the equation
        A*X = B,
     where A is an n by n tridiagonal matrix, by Gaussian elimination with
     partial pivoting.
     Note that the equation  A**T*X = B  may be solved by interchanging the
     order of the arguments DU and DL.

Parameters
    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.

    DL

              DL is DOUBLE PRECISION array, dimension (N-1)
              On entry, DL must contain the (n-1) sub-diagonal elements of
              A.
              On exit, DL is overwritten by the (n-2) elements of the
              second super-diagonal of the upper triangular matrix U from
              the LU factorization of A, in DL(1), ..., DL(n-2).

    D

              D is DOUBLE PRECISION array, dimension (N)
              On entry, D must contain the diagonal elements of A.
              On exit, D is overwritten by the n diagonal elements of U.

    DU

              DU is DOUBLE PRECISION array, dimension (N-1)
              On entry, DU must contain the (n-1) super-diagonal elements
              of A.
              On exit, DU is overwritten by the (n-1) elements of the first
              super-diagonal of U.

    B

              B is DOUBLE PRECISION array, dimension (LDB,NRHS)
              On entry, the N by NRHS matrix of right hand side matrix B.
              On exit, if INFO = 0, the N by NRHS 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, U(i,i) is exactly zero, and the solution
                   has not been computed.  The factorization has not been
                   completed unless i = N.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 126 of file dgtsv.f.

Author

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