public static void test6() {
    FTan tan = new FTan("x");
    System.out.println(tan.diff("x"));

    FAx fax = new FAx("x", 2.0);
    System.out.println(fax);
    System.out.println(fax.diff("x"));
    System.out.println(fax.compile().apply(5.0));

    FAxpb faxpb = new FAxpb("x", 2.0, 3.0);
    System.out.println(">>>" + faxpb);
    System.out.println(faxpb.diff("x"));
    System.out.println(faxpb.compile().apply(5.0));
  }
 public static void test3() {
   FAx fax = new FAx(2.0);
   fax.setName("fax");
   CompiledFunc cfax = fax.compile();
   System.out.println(cfax.apply(0.1));
 }