# Mathematica Help - Plotting equation with i

1. Feb 1, 2012

### tarheelborn

I cannot seem to make mathematica plot the following equation correctly:

r[t_] = 3 Cos[t] + iSin[t];
plotbeta = PolarPlot[r[t], {t, -Pi/2, Pi/2}]

I have used the capital I to no avail; I have used * to indicate multiplication. It plots the curve without a problem when I leave out the i, but I need the i! I will appreciate your help. Thank you.

2. Feb 2, 2012

### Bill Simpson

PolarPlot[], documented here,
http://reference.wolfram.com/mathematica/ref/PolarPlot.html
plots a Real radius as a function of the angle.

Do you really want to plot a surface in Complex space as a function of Complex radius?
If you want a PolarPlot that plots Complex radii then I don't know what to suggest.
There have been a few example complex plotting functions demonstrated over the years,
I think Roman Maeder developed one of these in the really really old book "Programming in Mathematica."

Or do you perhaps want
r[t_] = Abs[3 Cos[t] + I Sin[t]];
where Abs[] returns the Real distance from the origin to the point 3 Cos[t] + I Sin[t] in the complex plane?

3. Feb 8, 2012

### tarheelborn

I finally managed to get this using ParametricPlot. It worked beautifully; just took some tweaking! Thank you.