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Vector
src
SpaceVectorD.cc
Go to the documentation of this file.
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// -*- 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/defs.h"
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#include "CLHEP/Vector/ThreeVector.h"
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#include "CLHEP/Vector/ZMxpv.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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ZMthrowC
(ZMxpvAmbiguousAngle(
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"Cannot find azimuthal angle with reference direction parallel to "
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"vector 1 -- will return zero"
));
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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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ZMthrowC
(ZMxpvAmbiguousAngle(
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"Cannot find azimuthal angle with reference direction parallel to "
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"vector 2 -- will return zero"
));
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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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