The Math Shtick
 
The Power of the Imagination
     xi? It's mind boggling and interesting. It's a little more complicated than your normal exponent, but i can be saved in this predicament by another constant; e.
     e is useful here because ex can be written as:

     x0/0! + x1/1! + x2/2! + x3/3! + x4/4! + x5/5! + x6/6! + ...

     Therefore ei is:

     i0/0! + i1/1! + i2/2! + i3/3! + i4/4! + i5/5! + i6/6! + ...

     or

     1/0! + i/1! - 1/2! - i/3! + 1/4! + i/5! - 1/6! + ...

     Using this for ei, we can find xi by using the following equation:

     xi = (eln x)i = (ei)ln x = ei*(ln x)

     We can even generalize this for xy where y is any complex number.

     xy = (eln x)y = (ey)ln x = ey*(ln x)

     or

     (y*ln x)0/0! + (y*ln x)1/1! + (y*ln x)2/2! + (y*ln x)3/3! + (y*ln x)4/4! + (y*ln x)5/5! + (y*ln x)6/6! + ...

     If you know how to find the natural logarithm of a complex number, then you can say x is a complex number too.

     Now, what does it all mean?

That's odd?
      Calculating ln(i)

What's It Good For?
xi Calculating the Trig Functions
     
More Resources
      ii Explained By Dr. Math