private IExpression SimplifyDiv(Div div)
{
// 0 / x
if (div.Left.Equals(zero) && !div.Right.Equals(zero))
return zero;
// x / 0
if (div.Right.Equals(zero) && !div.Left.Equals(zero))
throw new DivideByZeroException();
// x / 1
if (div.Right.Equals(one))
return div.Left;
if (div.Left is Number && div.Right is Number)
return new Number((double)div.Calculate());
// (2 * x) / 2
// (x * 2) / 2
if (div.Left is Mul && div.Right is Number)
{
var bracketMul = div.Left as Mul;
var firstNumber = div.Right as Number;
if (bracketMul.Left is Number)
{
var secondNumber = bracketMul.Left as Number;
var result = new Div(bracketMul.Right, new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()));
return _Simplify(result);
}
if (bracketMul.Right is Number)
{
var secondNumber = bracketMul.Right as Number;
var result = new Div(bracketMul.Left, new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()));
return _Simplify(result);
}
}
// 2 / (2 * x)
// 2 / (x * 2)
else if (div.Right is Mul && div.Left is Number)
{
var bracketMul = div.Right as Mul;
var firstNumber = div.Left as Number;
if (bracketMul.Left is Number)
{
var secondNumber = bracketMul.Left as Number;
var result = new Div(new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()), bracketMul.Right);
return _Simplify(result);
}
if (bracketMul.Right is Number)
{
var secondNumber = bracketMul.Right as Number;
var result = new Div(new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()), bracketMul.Left);
return _Simplify(result);
}
}
// (2 / x) / 2
// (x / 2) / 2
else if (div.Left is Div && div.Right is Number)
{
var bracketDiv = div.Left as Div;
var firstNumber = div.Right as Number;
if (bracketDiv.Left is Number)
{
var secondNumber = bracketDiv.Left as Number;
var result = new Div(new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()), bracketDiv.Right);
return _Simplify(result);
}
if (bracketDiv.Right is Number)
{
var secondNumber = bracketDiv.Right as Number;
var result = new Div(bracketDiv.Left, new Number((double)firstNumber.Calculate() * (double)secondNumber.Calculate()));
return _Simplify(result);
}
}
// 2 / (2 / x)
// 2 / (x / 2)
else if (div.Right is Div && div.Left is Number)
{
var bracketDiv = div.Right as Div;
var firstNumber = div.Left as Number;
if (bracketDiv.Left is Number)
{
var secondNumber = bracketDiv.Left as Number;
var result = new Mul(new Number((double)firstNumber.Calculate() / (double)secondNumber.Calculate()), bracketDiv.Right);
return _Simplify(result);
}
if (bracketDiv.Right is Number)
{
var secondNumber = bracketDiv.Right as Number;
var result = new Div(new Number((double)firstNumber.Calculate() * (double)secondNumber.Calculate()), bracketDiv.Left);
return _Simplify(result);
}
}
return div;
}
public void CalculateTest()
{
IExpression exp = new Div(new Number(1), new Number(2));
Assert.AreEqual(1.0 / 2.0, exp.Calculate());
}
