Keep central density as seed data in the n1 sandbox

sandbox.cpp

@@ -99,9 +99,8 @@ int main(
         // const double polytropicConstant = 0.3639391; // Use for n=3 test
 
         std::println("K = {}", polytropicConstant);
-        const double centralDensity =
+        const double seedCentralDensity =
             std::numbers::pi_v<double> * mass / (4.0 * radius * radius * radius);
-        //const double centralDensity =12.9351146; // use for n=3 test
 
         auto stellarModel = model::StellarModel(
             eos::Polytrope({.n = 1.0, .K = polytropicConstant}),
@@ -111,8 +110,7 @@ int main(
                 .Jtotal = dimensions::AngularMomentumValue{angularMomentum},
                 .axis   = {0.0, 0.0, 1.0},
                 .center = {0.0, 0.0, 0.0}
-            }),
-            constraint::FixedCentralDensity({.RhoC = dimensions::DensityValue{centralDensity}})
+            })
         );
 
         auto discretization = equilibrium::makeStellarDiscretization(
@@ -126,8 +124,10 @@ int main(
         auto preconditioner = preconditioning::makePreconditioner();
         auto linearSolver   = solver::linear::FGMRES({.restartLength = 40, .printLevel = 1});
         const auto contextStart = std::chrono::steady_clock::now();
+        // This density initializes the seed; the n=1 equilibrium is free to change it.
         auto context             = solver::makeContext(
-            std::move(stellarModel), std::move(discretization), std::move(preconditioner), std::move(linearSolver)
+            std::move(stellarModel), std::move(discretization), std::move(preconditioner), std::move(linearSolver),
+            seed::LaneEmden({.centralDensity = dimensions::DensityValue{seedCentralDensity}})
         );
         if (rank == 0) {
             std::cout << "Solver context setup: "