TabFunct.hxx

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/*
 * Copyright (c) 2001-2004 MUSIC TECHNOLOGY GROUP (MTG)
 *                         UNIVERSITAT POMPEU FABRA
 *
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#ifndef __TABFUNCT__
#define __TABFUNCT__

#include "DataTypes.hxx"
#include "Assert.hxx"
#include <vector>

using std::vector;

namespace CLAM
{
template <class OriginalFunction> class TabFunct : public OriginalFunction
{
private:
        TabFunct() {};
public:
        TData operator() (const TData arg) {

                CLAM_DEBUG_ASSERT(arg>=mLowerBound && arg<=mUpperBound, "Tablulated functor argument out of bound");
                
                int index = int((arg-mLowerBound) / mIncr);

                CLAM_DEBUG_ASSERT(index<=mTableSize-2, "Bad index calculation");

                TData x1 = mLowerBound+mIncr*index;
                TData yIncr = mTable[index+1]-mTable[index];

                return mTable[index] + ((arg-x1) * yIncr) * mInvIncr;
        }

// constructor
        TabFunct(const unsigned tableSize, const TData lowerBound, const TData upperBound) :
                mLowerBound(lowerBound),
                mUpperBound(upperBound),
                mTableSize(tableSize)

        {
                CLAM_ASSERT(tableSize>=2, "Tabulating a function with less than 2 points.");
                CLAM_ASSERT(lowerBound < upperBound, "No interval left to calculate values");

                CalculateTable();
        }

private:
        
        void CalculateTable()
        {
                mTable.reserve(mTableSize);
                
                mIncr = (mUpperBound - mLowerBound) / (mTableSize-1);
                mInvIncr = 1/mIncr;

                TData arg = mLowerBound;

                for (int i=0; i<=mTableSize-1; arg+=mIncr, i++)
                        mTable[i] = OriginalFunction::operator() (arg);

        }
        // internal table
        vector<TData>      mTable;
        TData              mLowerBound;
        TData              mUpperBound;
        unsigned           mTableSize;
        TData              mIncr, mInvIncr;

};

} //namespace

#endif // TabFunct.hxx