factors out of integrand

Sample/HardParticle/HemiEllipsoid.cpp

@@ -51,19 +51,13 @@ complex_t HemiEllipsoid::formfactor_at_bottom(C3 q) const
     if (std::abs(q.mag()) <= std::numeric_limits<double>::epsilon())
         return M_TWOPI * R * W * H / 3.;
 
-    return M_TWOPI * H
+    return M_TWOPI * H * R * W
            * ComplexIntegrator().integrate(
                [=](double z) {
-                   double Rz = R * std::sqrt(1.0 - z * z);
-                   double Wz = W * std::sqrt(1.0 - z * z);
-
-                   complex_t qxRz = q.x() * Rz;
-                   complex_t qyWz = q.y() * Wz;
-
                    complex_t gamma = G * std::sqrt(1.0 - z * z);
                    complex_t J1_gamma_div_gamma = Math::Bessel::J1c(gamma);
 
-                   return Rz * Wz * J1_gamma_div_gamma * exp_I(q.z() * H * z);
+                   return (1. - z*z) * J1_gamma_div_gamma * exp_I(q.z() * H * z);
                },
                0., 1.);
 }