How to output a complex number in .Net 4.0?

How to output a complex number in .Net 4.0?

I import System.Numerics
However the following, nothing to output, it output NaN of whole equation
Complex aa = Math.Exp(-(1 / 4) * a * (b / a + Math.Sqrt(-7 * Math.Pow(b,
2) / Math.Pow(a, 2))) / b + (1 / 4) * b * (a / b + Math.Sqrt(-7 *
Math.Pow(a, 2) / Math.Pow(b, 2))) / a);
Jesus[i] = aa.Real;