Fix alpha_boundary documentation

src/nitschenonlinearpoissonfem.hh

@@ -102,11 +102,13 @@ namespace PPS {
         for (auto i : Dune::range(lb.size()))
           gradu.axpy(x[i],gradphi[i][0]);
 
-        // get unit outer normal vector and g
+        // get unit outer normal vector
         auto n = isect.unitOuterNormal(ip.position());
+        // get dirichlet boundary condition value
         auto g = this->param().g(isect, ip.position());
 
-        // integrate -(grad u)*n * phi_i + q(u)*phi_i
+        // integrate
+        // -(grad u)*n * phi_i - (u-g) * (grad phi_i)*n + stab*(u-g)*phi_i
         auto factor = ip.weight()*
           geo.integrationElement(ip.position());
         for (auto i : Dune::range(lb.size()))