/*
 * inquire number of vertical levels for ETA, SIGM, and ZHYB coordinats
 *
 * subc_eta_inq_zn(type1, type2, type3, basetime, member, validtime, group)
 *  arguments:
 *   type1, type2, type3, member: String
 *   basetime, validtime: Integer (minuits from 00:00 1 Jan 1801)
 *   group: "ETA", "SIGM", or "ZHYB"
 *  return:
 *    j_n: Integer
 */
VALUE
rb_subc_eta_inq_nz(VALUE self,
                   VALUE type1, VALUE type2, VALUE type3,
                   VALUE basetime, VALUE member, VALUE validtime,
                   VALUE group)
{
  GetTypes;
  GetTimesAndMember;
  GetChar(group, 4);

  N_SI4 cn_levels;
  N_SI4 code;

  code = nusdas_subc_eta_inq_nz(ctype1, ctype2, ctype3,
                                &cbasetime, cmember, &cvalidtime,
                                cgroup, &cn_levels);
  if ( code < 0 )
    rb_raise(rb_eRuntimeError, "faild");

  return INT2NUM( (int)cn_levels );
}