Gabriele Cosmo
77 lines
2.1 KiB
C++
77 lines
2.1 KiB
C++
// -*- C++ -*-
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// ---------------------------------------------------------------------------
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//
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// This file is a part of the CLHEP - a Class Library for High Energy Physics.
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//
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// This is the implementation of the subset of those methods of the Hep3Vector
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// class which originated from the ZOOM SpaceVector class *and* which involve
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// the esoteric concepts of polar/azimuthal angular decomposition.
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//
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#ifdef GNUPRAGMA
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#pragma implementation
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#endif
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#include "CLHEP/Vector/ThreeVector.h"
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#include <cmath>
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namespace CLHEP {
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//-*********************************************
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// - 6 -
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// Decomposition of an angle between two vectors
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//
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//-*********************************************
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double Hep3Vector::polarAngle (const Hep3Vector & v2) const {
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return std::fabs(v2.getTheta() - getTheta());
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} /* polarAngle */
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double Hep3Vector::polarAngle (const Hep3Vector & v2,
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const Hep3Vector & ref) const {
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return std::fabs( v2.angle(ref) - angle(ref) );
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} /* polarAngle (v2, ref) */
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// double Hep3Vector::azimAngle (const Hep3Vector & v2) const
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// is now in the .icc file as deltaPhi(v2)
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double Hep3Vector::azimAngle (const Hep3Vector & v2,
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const Hep3Vector & ref) const {
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Hep3Vector vperp ( perpPart(ref) );
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if ( vperp.mag2() == 0 ) {
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std::cerr << "Hep3Vector::azimAngle() - "
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<< "Cannot find azimuthal angle with reference direction parallel to "
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<< "vector 1 -- will return zero" << std::endl;
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return 0;
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}
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Hep3Vector v2perp ( v2.perpPart(ref) );
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if ( v2perp.mag2() == 0 ) {
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std::cerr << "Hep3Vector::azimAngle() - "
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<< "Cannot find azimuthal angle with reference direction parallel to "
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<< "vector 2 -- will return zero" << std::endl;
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return 0;
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}
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double ang = vperp.angle(v2perp);
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// Now compute the sign of the answer: that of U*(VxV2) or
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// the equivalent expression V*(V2xU).
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if ( dot(v2.cross(ref)) >= 0 ) {
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return ang;
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} else {
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return -ang;
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}
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//-| Note that if V*(V2xU) is zero, we want to return 0 or PI
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//-| depending on whether vperp is aligned or antialigned with v2perp.
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//-| The computed angle() expression does this properly.
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} /* azimAngle (v2, ref) */
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} // namespace CLHEP
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