Am Donnerstag, den 29.01.2009, 00:24 +0100 schrieb Dieter Kaiser: Sorry,there is a typo in the example (%i17) impagpart(bessel_j(n,x)); (%o17) impagpart(bessel_j(n, x)) Correct is (%i4) imagpart(bessel_j(n,x)); (%o4) 0 Dieter Kaiser