feat(equation-and-linear-solve): step 1 — essential-bc-elimination

src/fesa/fem/dof_manager.cpp

@@ -63,6 +63,15 @@ std::optional<std::size_t> DofManager::equation(
     return equations_[full_dof(address)];
 }
 
+std::optional<double> DofManager::prescribed_value(
+    const DofAddress address) const {
+    const std::size_t full = full_dof(address);
+    if (equations_[full].has_value()) {
+        return std::nullopt;
+    }
+    return prescribed_values_[full];
+}
+
 std::array<std::size_t, 12> DofManager::element_full_dofs(
     const BeamElement& element) const {
     std::array<std::size_t, 12> full_dofs{};