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)
    : AbsFunction(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 std::pow(x,_doublePower);
    }
 
}
 
 
 
Derivative Power::partial(unsigned int) 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