feat(polytrope-operator): finished computing the preconditioner

src/poly/utils/public/operator.h

@@ -64,15 +64,14 @@ private:
     /*
      * The schur preconditioner has the form
      *
-     * | df/drtheta^-1 0    |
-     * | 0             S^-1 |
+     *  ⎡ḟ(θ)^-1  0 ⎤
+     *  ⎣ 0     S^-1 ⎦
      *
      * Where S is the Schur compliment of the system
      *
      */
 
-    // TODO: I have not combined these parts yet and they need to be combined
-    mutable std::unique_ptr<mfem::SparseMatrix> m_schurPreconditioner;
+    mutable std::unique_ptr<mfem::BlockDiagonalPreconditioner> m_schurPreconditioner;
 
     bool m_isFinalized = false;