Fourier Series using fourie.mac



Hi,

During testing Fourier Series Expansion in maxima I found a problem I 
can't cope with.

(%i3)                            load(fourie)
(%o3)         /usr/share/maxima/5.18.1/share/calculus/fourie.mac
(%i4)                         f(x) := abs(sin(x))
(%o4)                         f(x) := abs(sin(x))
(%i5)                    flist : fourier(f(x), x, %pi)
                                          2
(%t5)                              a  = ---
                                     0   %pi

                      cos(%pi n)   cos(%pi n)      1         1
                   2 (---------- - ---------- + ------- - -------)
                       2 n + 2      2 n - 2     2 n + 2   2 n - 2
(%t6)        a  = -----------------------------------------------
               n                         %pi

(%t7)                               b  = 0
                                      n

(%o7)                           [%t5, %t6, %t7]
(%i8)                fs(n) := fourexpand(flist, x, %pi, n)
(%o8)                fs(n) := fourexpand(flist, x, %pi, n)
(%i9)                                fs(1)
Division by 0
#0: fourexpand(l=[%t5,%t6,%t7],x=x,p=%pi,nn=1)
#1: fs(n=1)(f.mac line 9)
  -- an error.  To debug this try debugmode(true);

how tell maxima that for n=1 a1=0 not inf?

RT