Issue running `make`

[Andrew-S-Rosen]

When running make using the version in main, I get the following error:

zeoran.cpp: In function 'void read_unit_cell(std::string)':
zeoran.cpp:215:39: error: reference to 'beta' is ambiguous
  215 |         fin >> aux >> alpha >> aux >> beta >> aux >> gama;
      |                                       ^~~~
In file included from /opt/cray/pe/gcc/11.2.0/snos/include/g++/cmath:1927,
                 from /opt/cray/pe/gcc/11.2.0/snos/include/g++/math.h:36,
                 from libraries.h:5,
                 from zeoran.cpp:1:
/opt/cray/pe/gcc/11.2.0/snos/include/g++/bits/specfun.h:343:5: note: candidates are: 'template<class _Tpa, class _Tpb> typename __gnu_cxx::__promote_2<_Tp, _Up>::__type std::beta(_Tpa, _Tpb)'
  343 |     beta(_Tpa __a, _Tpb __b)
      |     ^~~~
In file included from zeoran.cpp:2:
global.h:4:15: note:                 'double beta'
    4 | double alpha, beta, gama;
      |               ^~~~
zeoran.cpp: In function 'void print_structure(atom*, std::vector<int>, int, std::string, std::string, std::string)':
zeoran.cpp:853:41: error: reference to 'beta' is ambiguous
  853 |         fout << "_cell_angle_beta  " << beta << endl;
      |                                         ^~~~
In file included from /opt/cray/pe/gcc/11.2.0/snos/include/g++/cmath:1927,
                 from /opt/cray/pe/gcc/11.2.0/snos/include/g++/math.h:36,
                 from libraries.h:5,
                 from zeoran.cpp:1:
/opt/cray/pe/gcc/11.2.0/snos/include/g++/bits/specfun.h:343:5: note: candidates are: 'template<class _Tpa, class _Tpb> typename __gnu_cxx::__promote_2<_Tp, _Up>::__type std::beta(_Tpa, _Tpb)'
  343 |     beta(_Tpa __a, _Tpb __b)
      |     ^~~~
In file included from zeoran.cpp:2:
global.h:4:15: note:                 'double beta'
    4 | double alpha, beta, gama;
      |               ^~~~
make: *** [Makefile:5: zeoran] Error 1