[pstricks] Area under a Function

[Claus Behl]

Hi,
is it possible to fill the area indicating the integral from 1 to 3 
under the graph of f.
I want to fill the area under a curve with color. I draw the curve with 
a psplot command.
\psplot[]{-0.5}{4}{x 2 exp 0.25 mul 1 add}.

Claus Behl