PluginInterface::load_plugin: Cannot load shared library 'libcasadi_nlpsol_ipopt.so':    (     Searched directories: 1. casadipath from GlobalOptions                           2. CASADIPATH env var                           3. PATH env var (Windows)                           4. LD_LIBRARY_PATH env var (Linux)                           5. DYLD_LIBRARY_PATH env var (osx)     A library may be 'not found' even if the file exists:           * library is not compatible (different compiler/bitness)           * the dependencies are not found    )   Tried '/home/lyb/.local/lib/python2.7/site-packages/casadi' :     Error code: /home/lyb/.local/lib/python2.7/site-packages/casadi/libcasadi_nlpsol_ipopt.so: cannot open shared object file: No such file or directory   Tried '' :     Error code: libcasadi_nlpsol_ipopt.so: cannot open shared object file: No such file or directory   Tried '.' :     Error code: ./libcasadi_nlpsol_ipopt.so: cannot open shared object file: No such file or directory") [.../casadi/core/plugin_interface.hpp:142] Traceback (most recent call last):   File "color_line_det.py", line 197, in     nmpc_node()   File "color_line_det.py", line 175, in nmpc_node     sol = opti.solve()   File "/home/lyb/.local/lib/python2.7/site-packages/casadi/casadi.py", line 47774, in solve     return _casadi.Opti_solve(self, *args) RuntimeError: Error in Opti::solve [OptiNode] at .../casadi/core/optistack.cpp:157: .../casadi/core/plugin_interface.hpp:292: Plugin 'ipopt' is not found. ('1:', True)