@Test(dependsOnMethods = { "testSum" })
public void testFunctions() {
Expression evaluated;
Variable x = Numbers.variable("x");
Function exp = new Exp(x);
System.out.printf("%s%n", exp);
x.setValue(R.create(0));
evaluated = exp.evaluate();
System.out.printf(" %s%n", evaluated);
assertEquals(evaluated, Naturals.one());
x.setValue(R.create(1));
System.out.printf(" %s%n", exp.evaluate());
Function log = new Log(N.create(10), N.create(1000));
evaluated = log.evaluate();
System.out.printf("%s = %s%n", log, evaluated);
assertEquals(evaluated, N.create(3));
}