Newbie question : plotting an integrated function

["Philippe Saade" <psaade@gmail.com>]

Hi everybody,

i'am very sorry about this basic question but i am trying to find the
easiest way to plot (with matplotlib, gnuplot, anything .... but not
Maple(tm)) an integrated function

For example, \int_{x}^{2x} \dfrac{1}{1+\atan(t)}dt ...

** I though i would do it using python and scilab : (as a newbie) i'am
still looking in the doc

** i tried SAGE : i don't understand if it's a maxima/octave/???
choice and how i can do it exactly


Can anybody give me a hint ?

Thanks a lot

P. Saadé

(PS : any software available in SARGE would be fine, but EDGE is ok too..)