So, for those who didn't know, e^(πi) = -1. (For more information, see here [a basic calculus understanding is helpful.]).
Well, I was messing around with that a bit, so I ended up putting it into Y1. Now, when graphed, you would expect a horizontal line at y=-1, since it is just a number, right? Well, the graph showed up blank, and the table said error for all values of x. And value gives you no value for y. That's weird, right?
But it gets weirder still. When you do Y1(#) on the homescreen, where # is any real number, you end up with the result -1.

I'm running 1.13 on an 83+. Does this happen to any others, and why does it happen?

It looks like graphing simply doesn't support complex numbers in any capacity. For example, attempting to graph Y1=i² on an 84+SE with 2.55MP yields the same result.

Well then, why doesn't value work? Isn't that just plugging in your input for x?

Yeah, a simple real() should suffice.

No, i mean when you use 2nd-trace-value, you still don't get a result for plugging in a number.

Same thing happens, running 5.1 on the CE.

oh my, this might be some other issue, but when I try to graph Y=e^(πi), I got some strange gray block on the bottom of the screen, the rest of the stuff displayed is normal (those are the getkey codes and a radioactive symbol that I used in half-res mode which is why it is squished, in case you're curious) but one thing's for sure, it isn't a function! Anyways, here is a screenshot I grabbed

Hmmm... maybe a ClrDraw would resolve that.