Correction of the formula for the volume of a spheroid

Core/FormFactors/src/FormFactorSpheroid.cpp

@@ -74,7 +74,7 @@ complex_t FormFactorSpheroid::evaluate_for_q(const cvector_t& q) const
 
     if (std::abs(m_q.mag()) <= Numeric::double_epsilon) {
 
-        return M_PI*R*H/fp*(1.-H/(3.*fp*R));
+        return M_PI*R*H*H/fp*(1.-H/(3.*fp*R));
 
     } else {
 

Tests/UnitTests/TestCore/FormFactorTest.h

@@ -447,7 +447,8 @@ TEST_F(FormFactorTest, Spheroid)
     double radius = 3.;
     double flattening = 1.5;
     double total_height =2.*flattening *radius;
-    double volume = M_PI*radius*height/flattening*(1.-height/(3.*flattening*radius));
+    double volume = M_PI*radius*height*height/flattening
+            *(1.-height/(3.*flattening*radius));
 
     FormFactorSpheroid spheroid(radius, height,flattening);