Encapsulate Newton iteration in Integrator class (#442)

.gitignore

@@ -1,5 +1,27 @@
 build
 
+# CMake build artifacts
+CMakeCache.txt
+CMakeFiles/
+Makefile
+cmake_install.cmake
+*-build/
+*-prefix/
+
+# Compiled binaries and libraries
+Code/bin/
+Code/lib/
+
+# Generated headers
+Code/Source/Include/simvascular_options.h
+Code/Source/Include/simvascular_version.h
+Code/ThirdParty/*/simvascular_*.h
+
+# Vim swap files
+*.swp
+*.swo
+*~
+
 # System files osx 
 **/.DS_Store
 

Code/Source/solver/CMakeLists.txt

@@ -181,6 +181,7 @@ set(CSRCS
   heatf.h heatf.cpp
   heats.h heats.cpp
   initialize.h initialize.cpp
+  Integrator.h Integrator.cpp
   l_elas.h l_elas.cpp
   lhsa.h lhsa.cpp
   ls.h ls.cpp
@@ -191,7 +192,6 @@ set(CSRCS
   nn.h nn.cpp
   output.h output.cpp
   load_msh.h load_msh.cpp
-  pic.h pic.cpp
   post.h post.cpp
   read_files.h read_files.cpp
   read_msh.h read_msh.cpp

Code/Source/solver/ComMod.h

@@ -40,6 +40,40 @@
 
 class LinearAlgebra;
 
+/**
+ * @brief Represents solution variables at a single time level
+ *
+ * Contains the three primary solution arrays used in time integration:
+ * A (time derivative), D (integrated variable), and Y (variable)
+ */
+struct Solution {
+  Array<double> A;  ///< Time derivative (acceleration in structural mechanics)
+  Array<double> D;  ///< Integrated variable (displacement in structural mechanics)
+  Array<double> Y;  ///< Variable (velocity in structural mechanics)
+
+  // Semantic getters for improved readability
+  Array<double>& get_acceleration() { return A; }
+  const Array<double>& get_acceleration() const { return A; }
+
+  Array<double>& get_velocity() { return Y; }
+  const Array<double>& get_velocity() const { return Y; }
+
+  Array<double>& get_displacement() { return D; }
+  const Array<double>& get_displacement() const { return D; }
+};
+
+/**
+ * @brief Holds solution state at old and current time levels
+ *
+ * Contains solution arrays at two time levels for time integration:
+ * - old: Previous converged solution at time n
+ * - current: Current solution being computed at time n+1
+ */
+struct SolutionStates {
+  Solution old;      ///< Previous converged solution at time n (Ao, Do, Yo)
+  Solution current;  ///< Current solution being computed at time n+1 (An, Dn, Yn)
+};
+
 /// @brief Fourier coefficients that are used to specify unsteady BCs
 //
 class fcType
@@ -1749,18 +1783,6 @@ class ComMod {
     /// @brief RIS mapping array, with global (total) enumeration
      std::vector<Array2D> grisMapList;
 
-    /// @brief Old time derivative of variables (acceleration); known result at current time step
-    Array<double>  Ao;
-
-    /// @brief New time derivative of variables (acceleration); unknown result at next time step
-    Array<double>  An;
-
-    /// @brief Old integrated variables (displacement)
-    Array<double>  Do;
-
-    /// @brief New integrated variables (displacement)
-    Array<double>  Dn;
-
     /// @brief Residual vector
     Array<double>  R;
 
@@ -1770,12 +1792,6 @@ class ComMod {
     /// @brief Position vector of mesh nodes (in ref config)
     Array<double>  x;
 
-    /// @brief Old variables (velocity); known result at current time step
-    Array<double>  Yo;
-
-    /// @brief New variables (velocity); unknown result at next time step
-    Array<double>  Yn;
-
     /// @brief Body force
     Array<double>  Bf;