### Using "j" for Imaginary Unit?

This is probably trivial, but it's a minor annoyance that I'd like to fix.

Is there a way to define "j" to be the imaginary unit so that it not only represents "i" (in all expressions,etc.) but also appears in output as "j"?

```
sage: var('j,w,t')
(j, w, t)
sage: j=i
sage: j
I
sage: exp(j*w*t)
e^(I*t*w)
sage:
```

I'd like "j" to have the value of "i" but still appear as "j" in all output (LaTeX too!).