Drop bundled MINPACK; use fortnum multiroot for quasi symplectic steps

CMakeLists.txt

@@ -224,6 +224,18 @@ else()
     message(STATUS "Fortplot disabled for NVHPC compiler (compatibility issues)")
 endif()
 
+# fortnum provides the multidimensional root finder (multiroot_hybrids) that
+# replaced the bundled MINPACK hybrd1 in orbit_symplectic_quasi.
+if(NOT TARGET fortnum)
+    include(FetchContent)
+    FetchContent_Declare(
+        fortnum
+        GIT_REPOSITORY https://github.com/lazy-fortran/fortnum.git
+        GIT_TAG 92de6e949a772cfffc73bb5295fe5e2b056b9c18
+    )
+    FetchContent_MakeAvailable(fortnum)
+endif()
+
 if (SIMPLE_TESTING)
     message(STATUS "Unit Tests enabled!")
 endif()

src/CMakeLists.txt

@@ -1,8 +1,6 @@
     set(SOURCES
         ${CMAKE_BINARY_DIR}/version.f90
         lapack_interfaces.f90
-        contrib/minpack_interfaces.f90
-        contrib/minpack.f90
         sorting_mod.f90
         wall/chartmap_metadata.f90
         wall/stl_wall_intersection.F90
@@ -99,11 +97,6 @@ target_link_libraries(simple PUBLIC pyplot)
 # Apply SIMPLE-specific compile options
 target_compile_options(simple PRIVATE ${SIMPLE_COMPILE_OPTIONS})
 
-if(CMAKE_Fortran_COMPILER_ID MATCHES "GNU")
-    set_source_files_properties(contrib/minpack.f90 PROPERTIES
-        COMPILE_FLAGS "-Wno-compare-reals -Wno-implicit-interface -Wno-maybe-uninitialized")
-endif()
-
 # Apply trampoline error flags only to SIMPLE library (not subprojects like fortplot)
 if(CMAKE_Fortran_COMPILER_ID STREQUAL "GNU")
     target_compile_options(simple PRIVATE
@@ -120,6 +113,10 @@ target_link_libraries(simple PUBLIC
     LIBNEO::neo
 )
 
+target_link_libraries(simple PUBLIC
+    fortnum
+)
+
 # For NVHPC: add built deps includes first to avoid gfortran-compiled modules in /usr/include
 if(CMAKE_Fortran_COMPILER_ID STREQUAL "NVHPC")
     target_include_directories(simple BEFORE PUBLIC