TESTING/LIN/dgtt01.f(3)

NAME
TESTING/LIN/dgtt01.f

SYNOPSIS

  Functions/Subroutines
subroutine dgtt01 (n, dl, d, du, dlf, df, duf, du2, ipiv, work, ldwork, rwork, resid)
DGTT01

Function/Subroutine Documentation

  subroutine dgtt01 (integer n, double precision, dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double precision, dimension( * ) dlf, double precision, dimension( * ) df, double precision, dimension( * ) duf, double precision, dimension( * ) du2, integer, dimension( * ) ipiv, double precision, dimension( ldwork, * ) work, integer ldwork, double precision, dimension( * ) rwork, double precision resid)

DGTT01

Purpose:

     DGTT01 reconstructs a tridiagonal matrix A from its LU factorization
     and computes the residual
        norm(L*U - A) / ( norm(A) * EPS ),
     where EPS is the machine epsilon.

Parameters
    N

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

    DL

              DL is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) sub-diagonal elements of A.

    D

              D is DOUBLE PRECISION array, dimension (N)
              The diagonal elements of A.

    DU

              DU is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) super-diagonal elements of A.

    DLF

              DLF is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) multipliers that define the matrix L from the
              LU factorization of A.

    DF

              DF is DOUBLE PRECISION array, dimension (N)
              The n diagonal elements of the upper triangular matrix U from
              the LU factorization of A.

    DUF

              DUF is DOUBLE PRECISION array, dimension (N-1)
              The (n-1) elements of the first super-diagonal of U.

    DU2

              DU2 is DOUBLE PRECISION array, dimension (N-2)
              The (n-2) elements of the second super-diagonal of U.

    IPIV

              IPIV is INTEGER array, dimension (N)
              The pivot indices; for 1 <= i <= n, row i of the matrix was
              interchanged with row IPIV(i).  IPIV(i) will always be either
              i or i+1; IPIV(i) = i indicates a row interchange was not
              required.

    WORK

              WORK is DOUBLE PRECISION array, dimension (LDWORK,N)

    LDWORK

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

    RWORK

              RWORK is DOUBLE PRECISION array, dimension (N)

    RESID

              RESID is DOUBLE PRECISION
              The scaled residual:  norm(L*U - A) / (norm(A) * EPS)

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 132 of file dgtt01.f.

Author

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