Table.C

/*---------------------------------------------------------------------------*\
  =========                 |
  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
   \\    /   O peration     |
    \\  /    A nd           | Copyright (C) 1991-2007 OpenCFD Ltd.
     \\/     M anipulation  |
-------------------------------------------------------------------------------
License
    This file is part of OpenFOAM.

    OpenFOAM is free software; you can redistribute it and/or modify it
    under the terms of the GNU General Public License as published by the
    Free Software Foundation; either version 2 of the License, or (at your
    option) any later version.

    OpenFOAM is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    for more details.

    You should have received a copy of the GNU General Public License
    along with OpenFOAM; if not, write to the Free Software Foundation,
    Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

\*---------------------------------------------------------------------------*/

#include "Table.H"

// * * * * * * * * * * * * * * * * Constructors  * * * * * * * * * * * * * * //

template<class Type>
Foam::Table<Type>::Table
(
    const word& entryName,
    const dictionary& dict
)
:
    DataEntry<Type>(typeName, entryName, dict),
    table_(this->dict_.lookup("table"))
{
    if (!table_.size())
    {
        FatalErrorIn
        (
             "Foam::Table<Type>::Table"
             "("
                 "const word& entryName,"
                 "const dictionary& dict"
             ")"
        ) << "Table is invalid (empty)" << nl
          << exit(FatalError);
    }
}


// * * * * * * * * * * * * * * * * Destructor  * * * * * * * * * * * * * * * //

template<class Type>
Foam::Table<Type>::~Table()
{}


// * * * * * * * * * * * * * * * Member Functions  * * * * * * * * * * * * * //

template<class Type>
Type Foam::Table<Type>::value(const scalar x) const
{
    // Return zero if out of bounds
    if ((x > table_[table_.size()-1].first()) || (x < table_[0].first()))
    {
        return pTraits<Type>::zero;
    }

    // Find i such that x(i) < x < x(i+1)
    label i = 0;
    while ((table_[i+1].first() < x) && (i+1 < table_.size()))
    {
        i++;
    }

    // Linear interpolation to find value
    return
        (x - table_[i].first())/(table_[i+1].first() - table_[i].first())
      * (table_[i+1].second() - table_[i].second())
      + table_[i].second();
}


template<class Type>
Type Foam::Table<Type>::integrate(const scalar x1, const scalar x2) const
{
    // Initialise return value
    Type sum = pTraits<Type>::zero;

    // Return zero if out of bounds
    if ((x1 > table_[table_.size()-1].first()) || (x2 < table_[0].first()))
    {
        return sum;
    }

    // Find start index
    label id1 = 0;
    while ((table_[id1].first() < x1) && (id1 < table_.size()))
    {
        id1++;
    }

    // Find end index
    label id2 = table_.size() - 1;
    while ((table_[id2].first() > x2) && (id2 >= 1))
    {
        id2--;
    }

    // Integrate table body
    for (label i=id1; i<id2; i++)
    {
        sum +=
            (table_[i].second() + table_[i+1].second())
          * (table_[i+1].first() - table_[i].first());
    }
    sum *= 0.5;

    // Add table ends (partial segments)
    if (id1 > 0)
    {
        sum += 0.5
          * (value(x1) + table_[id1].second())
          * (table_[id1].first() - x1);
    }
    if (id2 < table_.size() - 1)
    {
        sum += 0.5
          * (table_[id2].second() + value(x2))
          * (x2 - table_[id2].first());
    }

    return sum;
}


// ************************************************************************* //