function Fbi = funBi(i, phi, p, AF, m)
%funBi(i, phi, p, AF, m)	calculates Fbi for the PSFip calculations
%
%
%Input variables:
%i = which out of four B to use
%phi = angle (degrees)
%p = pupil diameter (mm)
%AF = age factor = agefact(age)
%m = pigmentation parameter
%
%SEE PSFip, B1calc, B2calc, B3calc, B4calc
%

switch i
	
	case{1}
		Bi = B1calc(p, AF);
	case{2}
		Bi = B2calc(p, AF);
	case{3}
		Bi = B3calc(AF, m);
	case{4}
		Bi = 1;
end

Fbi = Bi/ (2 * pi * (((sin(phi)^2) + ((Bi^2) * ((cos(phi))^2)))^1.5));