/* method: to_s -- convert the data contents to a binary string */
static VALUE
 na_to_s(VALUE self)
{
  struct NARRAY *ary;
  GetNArray(self,ary);
  if (NA_IsROBJ(ary))
    rb_raise(rb_eTypeError,"cannot convert object-type NArray");
  return rb_str_new(ary->ptr,ary->total*na_sizeof[ary->type]);
}