#if !defined(ellipsoid_h)
#define ellipsoid_h

/**
 * Structure definition for ellipsoid parameters
 * The ellipsoid has axes radius_b, radius_b, radius_a.
 * Ref: Jan Skov Pedersen, Advances in Colloid and Interface Science, 70 (1997) 171-210
 */
 //[PYTHONCLASS] = EllipsoidModel
 //[DISP_PARAMS] = radius_a, radius_b, axis_theta, axis_phi
 //[DESCRIPTION] = <text>"P(q.alpha)= scale*f(q)^(2)+ bkg\n\
 //					f(q)= 3*(scatter_sld- scatter_solvent)*V*[sin(q*r(Ra,Rb,alpha)) - q*r*cos(qr(Ra,Rb,alpha))]
 //							/[qr(Ra,Rb,alpha)]^(3)"
 //						r(Ra,Rb,alpha)= [Rb^(2)*(sin(alpha))^(2) + Ra^(2)*(cos(alpha))^(2)]^(1/2)
 //						scatter_sld: scattering length density of the scatter
 //						solvent_sld: scattering length density of the solvent
 //						V: volune of the Eliipsoid
 //						Ra: radius along the rotation axis of the Ellipsoid
 //						Rb: radius perpendicular to the rotation axis of the ellipsoid
 //						</text>
 //[FIXED]= <text> axis_phi.width; axis_theta.width;radius_a.width;
 //radius_b.width; length.width; r_minor.width
 //, r_ratio.width</text>
typedef struct {
    /// Scale factor
    //  [DEFAULT]=scale=1.0
    double scale;

    ///	Rotation axis radius_a [A]
    //  [DEFAULT]=radius_a=20.0 A
    double radius_a;

    /// Radius_b [A]
    //  [DEFAULT]=radius_b=400 A
    double radius_b;

    ///	Contrast [Å-2]
    //  [DEFAULT]=contrast=3.0e-6 A-2
    double contrast;

	/// Incoherent Background [cm-1]
	//  [DEFAULT]=background=0 cm-1
	double background;

    /// Orientation of the long axis of the ellipsoid w/respect incoming beam [rad]
    //  [DEFAULT]=axis_theta=1.57 rad
    double axis_theta;
    /// Orientation of the long axis of the ellipsoid in the plane of the detector [rad]
    //  [DEFAULT]=axis_phi=0.0 rad
    double axis_phi;
} EllipsoidParameters;



/// 1D scattering function
double ellipsoid_analytical_1D(EllipsoidParameters *pars, double q);

/// 2D scattering function
double ellipsoid_analytical_2D(EllipsoidParameters *pars, double q, double phi);
double ellipsoid_analytical_2DXY(EllipsoidParameters *pars, double qx, double qy);
double ellipsoid_analytical_2D_scaled(EllipsoidParameters *pars, double q, double q_x, double q_y);

#endif