public void DerivativeTest2()
{
Number num = new Number(2);
Variable x = new Variable("x");
Mul mul = new Mul(num, x);
IExpression exp = new Abs(mul);
IExpression deriv = exp.Differentiate();
Assert.AreEqual("(2 * 1) * ((2 * x) / abs(2 * x))", deriv.ToString());
num.Value = 3;
Assert.AreEqual("abs(3 * x)", exp.ToString());
Assert.AreEqual("(2 * 1) * ((2 * x) / abs(2 * x))", deriv.ToString());
}
public void PartialDerivativeTest2()
{
IExpression exp = new Abs(new Mul(new Variable("x"), new Variable("y")));
IExpression deriv = exp.Differentiate(new Variable("y"));
Assert.AreEqual("(x * 1) * ((x * y) / abs(x * y))", deriv.ToString());
}