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Power.cc

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// -*- C++ -*-
// $Id: Power.cc,v 1.4 2003/10/10 17:40:39 garren Exp $
#include "CLHEP/GenericFunctions/Power.hh"
#include <cmath>      // for pow()

namespace Genfun {
FUNCTION_OBJECT_IMP(Power)

Power::Power(int n):
    _intPower(n),
    _asInteger(true)
{}

Power::Power(unsigned int n):
    _intPower(n),
    _asInteger(true)
{}

Power::Power(double n):
    _doublePower(n),
    _asInteger(false)
{}

Power::Power(const Power & right)
    : _doublePower(right._doublePower),
      _intPower(right._intPower),
      _asInteger(right._asInteger)
{}

Power::~Power() {
}

double Power::operator() (double x) const {
    if (_asInteger) {
        if (_intPower==0) {
            return 1;
        }
        else if (_intPower>0) {
            double f = 1;
            for (int i=0;i<_intPower;i++) {
                f *=x;
            }
            return f;
        }
        else {
            double f = 1;
            for (int i=0;i<-_intPower;i++) {
                f /=x;
            }
            return f;
        }           
    }
    else {
        return pow(x,_doublePower);
    }

}



Derivative Power::partial(unsigned int index) const {
  if (_asInteger) {
    const AbsFunction & fPrime = _intPower*Power(_intPower-1);
    return Derivative(&fPrime);
  }
  else {
    const AbsFunction & fPrime = _doublePower*Power(_doublePower-1);
    return Derivative(&fPrime);
  }

}


} // namespace Genfun

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