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#ifndef INLINE_MATHS
#define INLINE_MATHS
// This file is distributed with FastJet under the terms of the GNU
// General Public License (v2). Permission to do so has been granted
// by Lars Sonnenschein and the D0 collaboration (see COPYING for
// details)
//
// History of changes in FastJet compared tothe original version of
// inline_math.h
//
// 2011-12-13 Gregory Soyez <soyez@fastjet.fr>
//
// * added license information
//
// 2009-01-17 Gregory Soyez <soyez@fastjet.fr>
//
// * put the code in the fastjet::d0 namespace
#include <cerrno>
#include <fastjet/internal/base.hh>
FASTJET_BEGIN_NAMESPACE
namespace d0{
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 d0
FASTJET_END_NAMESPACE
#endif
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