function F = flux(nth,nphi)
% Flux from a limb darkened spherical star.
%
% D. Holmgren holmgren@phobos.astro.uwo.ca

theta = linspace(0,pi,nth)';
phi = linspace(-pi/2,pi/2,nphi)';
dth = theta(2)-theta(1); dphi = phi(2)-phi(1);
sum = 0.; u = 0.6;
for k = 1:nth
  for l = 1:nphi
    sum = sum + (1 - u + u*cos(theta(k)))*cos(theta(k))*sin(theta(k));
  end
end
F = sum*dth*dphi