public void ToStringVarTest()
{
var deriv = new Derivative(new Sin(new Variable("x")), new Variable("x"));
Assert.Equal("deriv(sin(x), x)", deriv.ToString());
}
public void ToStringPointTest()
{
var deriv = new Derivative(new Sin(new Variable("x")), new Variable("x"), new Number(1));
Assert.Equal("deriv(sin(x), x, 1)", deriv.ToString());
}
