[metapost] Function defined by a sum

[Nicolas FRANCOIS]

Hi.

I'd like to show the Gibbs phenomenon on an example. For this I'd like to
draw the partial sums of the Fourier serie :

  sum(sin(n*x)/n,n=1..infty)

For the first five partial sums, I can of course tpe them by hand. But
what about the sum number 20 ? And 50 ? Is there a "sum" construction
available in Metapost ? Or some for loop ?

Thanks for any help.

\bye

-- 

                   Nicolas FRANCOIS
            http://nicolas.francois.free.fr
 A TRUE Klingon programmer does NOT comment his code