double Moon::Angle ( double  r, double  d  ) const

inline

Definition at line 402 of file smartfact.cc.

    {
        const double theta0 = M_PI/2-d*M_PI/180;
        const double phi0   = r*M_PI/12;

        const double theta1 = M_PI/2-dec*M_PI/180;
        const double phi1   = ra*M_PI/12;

        const double x0 = sin(theta0) * cos(phi0);
        const double y0 = sin(theta0) * sin(phi0);
        const double z0 = cos(theta0);

        const double x1 = sin(theta1) * cos(phi1);
        const double y1 = sin(theta1) * sin(phi1);
        const double z1 = cos(theta1);

        double arg = x0*x1 + y0*y1 + z0*z1;
        if(arg >  1.0) arg =  1.0;
        if(arg < -1.0) arg = -1.0;

        return acos(arg) * 180/M_PI;
    }