#include "Fraunhofer.h"
#include <math.h>

// ---------------------------------------------------------------------------------
//		¥ CreateFraunhoferFit [static]
// ---------------------------------------------------------------------------------

FitFunction *
FraunhoferFit::CreateFraunhoferFit( )
{
	return NEW FraunhoferFit();
}


FraunhoferFit::FraunhoferFit() : FitFunction(false, true)
{
	// Add the parameters
	
	FitParameter *fp;
	
	// The functional form is
	
	AddParameter( NEW FitParameter("Intensity", 1.0) );
	AddParameter( NEW FitParameter("Center Position (mm)", 10) );
	AddParameter( NEW FitParameter("Radius (mm)", 0.1) );
	AddParameter( NEW FitParameter("Object Distance (mm)", 1500) );
	
	AddParameter( fp = NEW FitParameter("Wavelength", 0.0006328) );
	fp->Lock();
}

FraunhoferFit::~FraunhoferFit()
{
}


// Remember that fit parameters are 1-based


REAL FraunhoferFit::CalcFitFunction(REAL x)
{

	x -= Param(2)();							// the center position parameter
	REAL argument = 2 * 3.14159265358979 / Param(5)();	// k
	argument *= Param(3)() * x / Param(4)();
	
	REAL result = argument == 0.0 ? 1.0 : 2.0 * BesselJ1(argument) / argument;
	return result * result * Param(1)();
}