[PL] Added CMake option to use EigenLis solver

CMakeLists.txt

@@ -64,6 +64,8 @@ option(OGS_NO_EXTERNAL_LIBS "Builds OGS without any external dependencies." OFF)
 # Linear solvers
 option(OGS_USE_LIS "Use Lis" OFF)
 
+option(OGS_USE_EIGENLIS "Use Lis solver together with Eigen sparse matrices" OFF)
+
 # Parallel computing: vector and matrix algebraic caculation, solvers
 option(OGS_USE_PETSC "Use PETSc routines" OFF)
 
@@ -147,6 +149,15 @@ if(OGS_USE_EIGEN)
 	include_directories (SYSTEM ${EIGEN3_INCLUDE_DIR})
 endif()
 
+if (OGS_USE_EIGENLIS)
+	if (OGS_USE_EIGEN AND OGS_USE_LIS)
+		add_definitions(-DOGS_USE_EIGENLIS)
+	else()
+		message(WARNING "The setting OGS_USE_EIGENLIS needs both OGS_USE_EIGEN"
+		        " and OGS_USE_LIS set in order to have some effect.")
+	endif()
+endif()
+
 add_subdirectory( Applications )
 add_subdirectory( AssemblerLib )
 add_subdirectory( BaseLib )

ProcessLib/NumericsConfig.h

@@ -23,7 +23,21 @@
 //
 // Global vector/matrix types and linear solver.
 //
-#if defined(USE_LIS)
+#if defined(OGS_USE_EIGENLIS)
+
+    #include "MathLib/LinAlg/Eigen/EigenMatrix.h"
+    #include "MathLib/LinAlg/Eigen/EigenVector.h"
+    #include "MathLib/LinAlg/EigenLis/EigenLisLinearSolver.h"
+
+    namespace detail
+    {
+    using GlobalVectorType = MathLib::EigenVector;
+    using GlobalMatrixType = MathLib::EigenMatrix;
+
+    using LinearSolverType = MathLib::EigenLisLinearSolver;
+    }
+
+#elif defined(USE_LIS)
 
     #include "MathLib/LinAlg/Lis/LisMatrix.h"
     #include "MathLib/LinAlg/Lis/LisVector.h"