SymPy Gamma

SymPy:

plot (y =x,y1 =x**2,r =cos (theta),r1 =sin (theta))

$\mathrm{Plot~}\left\{ r : \cos{\left(\theta \right)}, \ r1 : \sin{\left(\theta \right)}, \ y : x, \ y1 : x^{2}\right\}$

Plot:

plot(y=x, y1=x**2, r=cos(theta), r1=sin(theta))

See what Wolfram|Alpha has to say.

Experiment with SymPy at SymPy Live.