Optimize integrands in form factor quadrature

Sample/HardParticle/TruncatedSpheroid.cpp

@@ -39,25 +39,20 @@ TruncatedSpheroid::TruncatedSpheroid(double radius, double height, double height
 complex_t TruncatedSpheroid::formfactor_at_bottom(C3 q) const
 {
     ASSERT(m_validated);
-    double H = m_height;
-    double R = m_radius;
-    double fp = m_fp;
+    const double H = m_height;
+    const double R = m_radius;
+    const double fp = m_fp;
 
     if (std::abs(q.mag()) <= std::numeric_limits<double>::epsilon())
         return M_PI / 3. / fp * (H * H * (3. * R - H / fp) - m_dh * m_dh * (3. * R - m_dh / fp));
 
-    complex_t z_part = exp_I(q.z() * (H - fp * R));
-    return M_TWOPI * z_part
+    return M_TWOPI * exp_I(q.z() * (H - fp * R))
            * ComplexIntegrator().integrate(
                [=](double Z) {
-                   double R = m_radius;
-                   double fp = m_fp;
-
                    double Rz = std::sqrt(R * R - Z * Z / (fp * fp));
                    complex_t qrRz = std::sqrt(q.x() * q.x() + q.y() * q.y()) * Rz;
-                   complex_t J1_qrRz_div_qrRz = Math::Bessel::J1c(qrRz);
 
-                   return Rz * Rz * J1_qrRz_div_qrRz * exp_I(q.z() * Z);
+                   return Rz * Rz * Math::Bessel::J1c(qrRz) * exp_I(q.z() * Z);
                },
                fp * R - H, fp * R - m_dh);
 }