// sv-3.cc
// 		A ZOOM PhysicsVectors tutorial example
//
// 		Tutorial example 3 for the SpaceVector and UnitVector class:
//
// 		UnitVectors
//
// * Constructing UnitVectors
// * Using different forms of coordinates
// * Changing individual components
// * The coordinate axis UnitVectors

// Key lines are marked by 				    // <-------------

	// Get the UnitVector class

#include "ZMutility/ZMenvironment.h"
#include "ZMutility/FixedTypes.h"
#include "PhysicsVectors/UnitVector.h"
ZM_USING_NAMESPACE( zmpv )
USING( std::cout )
USING( std::endl )

	// These classes themselves pull in FixedTypes, but just to
	// remind ourselves that we are using Float8, not double, for
	// 64-bit floats...

#include "ZMutility/FixedTypes.h"
ZM_USING_NAMESPACE( zmfxt )

	// This example will use iostream output, so get that --
	// in a portable way.

#include "ZMutility/iostream"
using std::cout;
using std::endl;

const Float8 PI =  3.1415926535897931;


int main() {

// ***** Constructing a UnitVector

	// Here is how to construct a unit vector from theta, phi
	//-------------------------------------------------------

  cout << "Constructing u1 from theta and phi \n";

  Float8 theta = 45;
  Float8 phi   = 30;

  UnitVector u1 ( theta, DEGREES, phi, DEGREES );	    // <-------------

	// Note the use of the keyword DEGREES; this and RADIANS
	// can be mixed, if you wish.

  UnitVector u2 ( 45, DEGREES, PI/6, RADIANS );

  cout << "u1 =" << u1 << endl;
  cout << "u2 =" << u1 << endl;

	// Here is how to construct a unit vector by normalizing x, y, z
	//--------------------------------------------------------------

  cout << "Constructing u3 by normalizing cartesian coordinates \n";

  Float8 x = 3;
  Float8 y = 4;
  Float8 z = 12;
  UnitVector u3 ( x, y, z );				    // <-------------

  cout << "u3 =" << u3 << endl;

//cout << "13 times that UnitVector is " << 13 * SpaceVector(u3) << endl;
  cout << "13 times that UnitVector is " << 13 * u3 << endl;

	// Here is how to construct a unit vector by normalizing a SpaceVector
	//--------------------------------------------------------------------

  SpaceVector v1 (24, 6, -8);

  UnitVector u4(v1);					    // <-------------

  cout << "The UnitVector constructed from " << v1 << " is " << u4 << endl;

        // How to construct an array of UnitVectors:
        //-------------------------------------------

        // These hundred UnitVectors will be initialized to (0,0,1) = Z_HAT

  UnitVector uu [100];


// ***** Using different forms of coordinates

	// Here is how to obtain the polar coordinates of a UnitVector:
	//--------------------------------------------------------------

  theta = u1.theta();					    // <-------------
  phi = u1.phi();					    // <-------------
  Float8 r = u1.r();					    // <-------------

  	// u1.r(), of course, returns 1 without having to think.

  cout << "u1 has r= " << r << " theta = " << theta << " phi = " << phi << endl;

	// Here is how to obtain the Cartesian coordinates of a UnitVector:
	//------------------------------------------------------------------

  x = u2.x();						    // <-------------
  y = u2.y();						    // <-------------
  z = u2.z();						    // <-------------

  cout << "u2 has x= " << x << " y = " << y << " z = " << z << endl;


// ***** Changing individual components

	// Here is how to change phi or theta, keeping the other fixed
	//------------------------------------------------------------

  cout << "u1 =" << u1 << endl;

  u1.setPhi( -PI/6 );					    // <-------------
  cout << "Now u1 =" << u1 << endl;
  u1.setTheta( PI/3 );					    // <-------------
  cout << "Now u1 =" << u1 << endl;

	// You can also use the modify/assign operators

  u1.setPhi( u1.phi() * -1 );				    // <-------------
  cout << "I negated phi; now u1 =" << u1 << endl;

	// Here is how to change phi and theta both at once
	//-------------------------------------------------

  u2.set ( 45, DEGREES, PI, RADIANS );			    // <-------------
  cout << "Now u2 =" << u2 << endl;

// ***** The coordinate axis UnitVectors

	// Here is how to use X_HAT, Y_HAT and Z_HAT
	//------------------------------------------

  UnitVector  u5 = Y_HAT;				    // <-------------
  cout << "Y_HAT = " << u5 << endl;

  SpaceVector v3 = X_HAT - Z_HAT;			    // <-------------
  cout << "X_HAT - Z_HAT = " << v3 << endl;

	// Notice that the sum of two UnitVectors is a SpaceVector

  return 0;

} /* end of main */