Equation Calculator with Graphing

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CommonUtils
{
	class EquationUnitTestException : Exception
	{
		public string Equation {get; set;}
		public EquationUnitTestException(string equation, string message) : base(message)
		{
			Equation = equation;
		}
	}

	public class EquationUnitTest
	{
		Term m_term = new Term();
		public EquationUnitTest()
		{
		}
		public void UnitTest()
		{
			Assert("2+3*5", 2+3*5);
			Assert("2+3*5^2", 2+3*Math.Pow(5,2));
			Assert("2+3*5/2*2", 2d+3d*5d/2d*2d);
			Assert("2pi", 2d*Math.PI);
			Assert("2pi2", 2d*Math.PI*2d);
			Assert("3(3+2)(2*5)", 3*(3+2)*(2*5));
			Assert("100^-1", Math.Pow(100, -1));
			Assert("3^2+3*3-18", 0);
			Assert("4^2+3*4-18", 10);
			
			m_term.SetVar("x", -2);
			Assert("(2x+4)/(x^2-7)", 0);
			
			m_term.SetVar("a", 5);
			m_term.SetVar("b", 5);
			Assert("2aba", 250);
			Assert("2abs(-10)", 20);
			Assert("sqrt(10^2)", 10);
			
			Assert("sin(0)", 0);
			Assert("sin(pi/2)", 1);
			Assert("sin(pi/4)", Math.Sin(Math.PI / 4));
			Assert("sin((45/180)pi)", Math.Sin((45d/180d)*Math.PI));
			Assert("tan(pi/2)", Math.Tan(Math.PI/2));

			m_term.SetVar("ans", 5);
			Assert("ans+2", 7);

			m_term.SetVar("ans", 16);
			Assert("sqrt(ans)+2", 6);

			m_term.SetVar("ans", 10);
			Assert("2*-ans", -20);

			m_term.SetVar("ans", 10);
			m_term.SetVar("a", 2);
			m_term.SetVar("n", 3);
			Assert("a n ans", 60);

			Assert("2 * e", 2 * Math.E);
			Assert("2e", 2 * Math.E);
			Assert("2e10", (double)2e10);
			Assert("5.0805263425E-5 * 2", 2 * (double)5.0805263425E-5);
			Assert("4.35718618402138E+21*2", ((double)4.35718618402138E+21)*2);
			Assert("10E10*2", ((double)10E10)*2);

			Assert("ln(3^e)", Math.Log(Math.Pow(3, Math.E), Math.E/*3*/));

			Assert("Log(1000)", 3);
			Assert("Log(27, 3)", 3);
			Assert("Log(4^4, 4)", 4);
			Assert("-sin(-4)", -Math.Sin(-4));
		}

		void Assert(string equation, double result)
		{
			try
			{
				m_term.Parse(equation);
				if (m_term.Value != result)
				{
					string text = string.Format("FAILED - Equation {0}, Parsed {1}, Value {2}, Expected {3}", equation, m_term.ToString(), m_term.Value, result);
					throw new EquationUnitTestException(equation, text);
				}
				Console.WriteLine(string.Format("PASSED - Equation {0}, Parsed {1}, Value {2}", equation, m_term.ToString(), m_term.Value));
			}
			catch (Exception error)
			{
				throw new EquationUnitTestException(equation, error.Message);
			}
			m_term.ClearVars();
		}
	}
}