inline_maths.hh
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inline_maths.hh
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	#ifndef INLINE_MATHS
	#define INLINE_MATHS

	#include <cerrno>

	namespace SpartyJet {

	namespace inline_maths {

	const double PI = fabs(acos(-1.));

	const double TWOPI = 2*PI;


	inline double sqr(double a) {
	return a*a;
	}



	inline double min(double a, double b) {
	return (a < b) ? a : b;
	}



	inline double delta_phi(double phi1, double phi2) {
	return min( double(fabs(phi1-phi2)), double(2.*PI-fabs(phi1-phi2)) );
	}



	inline double phi(double px, double py) {
	return atan2(py, px);
	}



	inline double y(double E, double pz) {
	errno=0;
	double y;
	//cout << "inline_maths: ";
	if (fabs(E-pz) == 0.) {
	// cout << "Error in header mathe.h: division by 0 in function eta!" << " p=" << p << " pz=" << pz << endl;
	// exit(721);
	errno=721;
	y = 99999.;
	}
	else {
	y = 0.5*log((E+pz)/(E-pz));
	}
	//cout << "y: E=" << E << " pz=" << pz << " y=" << y << endl;
	return y;
	}


	} //end usename inline_maths




	} // namespace SpartyJet
	#endif