The three functions are solid_angle_calc, solid_angle_calc2, calc_omega, all of which take four arguments:. solid_angle_calc(p, q, h, a, b) returns the solid angle subtended by an ellipse with ...

I can only see the atan function in the code, and I don't know where the atan function is used either. The atan function is known as 90° support rather than 180° support, but only the atan function ...