static char* filter_atom_type=  "{\
  int i;\
  int output_atoms; \
  \
  output.timestamp = input.timestamp; \
  output.natoms = input.natoms; \
  output.na3 = input.na3; \
  output.nbonds = 0;\
  output.nb_2 = 0; \
  output_atoms = 0; \
  for (i=0; i<input.natoms; i=i+1){\
    if (input.itype[i] != 2) { \
      output.itype[output_atoms] = input.itype[i];\
	  output.xatoms[output_atoms*3] = input.xatoms[i*3];\
	  output.xatoms[output_atoms*3+1] = input.xatoms[i*3+1];\
	  output.xatoms[output_atoms*3+2] = input.xatoms[i*3+2];\
	  output_atoms = output_atoms + 1;\
	}\
  }\
  output.natoms = output_atoms; \
  output.na3 = output_atoms*3;\
  return 1;\
}\0\0";