feat(surface): surface deformation prescriptions

restricted the unknown state vector to surface deformation and implemented one prescription, NodalRadialSurface, while the full volumetric displacment field is reconstructed analytically from that. This reduced the number of degrees of freedom in the system by a factor of 80 while also removing many null vectors from the system.

CMakeLists.txt

@@ -5,6 +5,12 @@ set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+set(MEAN_FIELD_UNIFORM_POLYNOMIAL_ORDER_INCREMENT 0 CACHE STRING
+        "Uniform increment applied to every registered finite-element family order")
+if (NOT MEAN_FIELD_UNIFORM_POLYNOMIAL_ORDER_INCREMENT MATCHES "^[0-9]+$")
+    message(FATAL_ERROR "MEAN_FIELD_UNIFORM_POLYNOMIAL_ORDER_INCREMENT must be a non-negative integer")
+endif ()
+
 add_compile_options(
         -gdwarf-4
         -Wno-unused-parameter
@@ -34,6 +40,11 @@ pkg_check_modules(stroid REQUIRED IMPORTED_TARGET stroid)
 
 add_library(mean_field)
 
+target_compile_definitions(mean_field
+        PUBLIC
+        MEAN_FIELD_UNIFORM_POLYNOMIAL_ORDER_INCREMENT=${MEAN_FIELD_UNIFORM_POLYNOMIAL_ORDER_INCREMENT}
+)
+
 target_include_directories(mean_field
         PUBLIC
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/libmeanfield/include>
@@ -57,6 +68,8 @@ target_sources(mean_field
         libmeanfield/impl/integrators/viscosity.cpp
         libmeanfield/impl/mapping/domain_mapper.cpp
         libmeanfield/impl/mapping/transformations.cpp
+        libmeanfield/impl/deformation/nodal_radial_surface.cpp
+        libmeanfield/impl/deformation/radial_extensions.cpp
         libmeanfield/impl/operators/gravity_field.cpp
         libmeanfield/impl/operators/gravity_field_jacobian.cpp
         libmeanfield/impl/operators/kernels/gravity_kernels.cpp
@@ -152,6 +165,13 @@ target_sources(mean_field
         libmeanfield/interface/surface/dependencies.cppm
         libmeanfield/interface/surface/compiled.cppm
         libmeanfield/interface/surface/compiler.cppm
+        libmeanfield/interface/deformation/descriptors.cppm
+        libmeanfield/interface/deformation/surface_prescription.cppm
+        libmeanfield/interface/deformation/nodal_radial_surface.cppm
+        libmeanfield/interface/deformation/interior_extension.cppm
+        libmeanfield/interface/deformation/vacuum_extension.cppm
+        libmeanfield/interface/deformation/radial_extensions.cppm
+        libmeanfield/interface/deformation/domain_deformation.cppm
         libmeanfield/interface/models/stellar_model.cppm
         libmeanfield/interface/operators/prepared_mass_normalization.cppm
         libmeanfield/interface/operators/prepared_centering_constraint.cppm
@@ -231,6 +251,11 @@ add_executable(tests
         tests/operators/prepared_rotation_displacement_force_affine_deformation.cpp
         tests/operators/prepared_displacement_operator.cpp
         tests/models/stellar_model.cpp
+        tests/deformation/contracts.cpp
+        tests/deformation/surface_scalar_dof_map.cpp
+        tests/deformation/nodal_radial_surface.cpp
+        tests/deformation/radial_extensions.cpp
+        tests/deformation/domain_deformation.cpp
         tests/operators/prepared_mass_normalization.cpp
         tests/operators/prepared_stellar_equilibrium.cpp
         tests/utils/domain.cpp
@@ -266,6 +291,7 @@ add_executable(stellar_null_space_experiments
         experiments/experiment_main.cpp
         experiments/rigid_motion_null_space.cpp
         experiments/gravity_completed_rigid_motion.cpp
+        experiments/coupled_gauge_modes.cpp
 )
 
 target_link_libraries(stellar_null_space_experiments