title: Operator '+' can't be applied to operands of types 'decimal' and 'double' - NCalc
body: <p>I'm using <a href="http://ncalc.codeplex.com" rel="nofollow">NCalc</a> to evaluate complex expressions. But I've found a major problem.</p>
  
  <p>A simple formula like <code>new Expression("Abs(-1) + Cos(2)").Evaluate()</code> throws the exception</p>
  
  <pre><code>Operator '+' can't be applied to operands of types 'decimal' and 'double
  </code></pre>
  
  <p>In C# code <code>Math.Abs(-1) + Math.Cos(2)</code> works, so either I'm doing something wrong or there is a bug in NCalc.</p>
  
  <p>Does anyone have the same problem?</p>
  
  <p>Does anyone have a solution?</p>
  
  <p>The only thread i found on the project's website related to this error is quite old and talks about editing the source code.
  <a href="https://ncalc.codeplex.com/discussions/346702" rel="nofollow">https://ncalc.codeplex.com/discussions/346702</a></p>
  
  <p>I also posted a question on their forum but StackOverflow is usualy more dynamic.
  <a href="https://ncalc.codeplex.com/discussions/613634" rel="nofollow">https://ncalc.codeplex.com/discussions/613634</a></p>