Integrate[] crashes kernel

*To*: mathgroup at smc.vnet.net*Subject*: [mg50733] Integrate[] crashes kernel*From*: math5bug at lmm.jussieu.fr (B. Oudoli)*Date*: Sat, 18 Sep 2004 05:48:47 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Hi all, I've found a fairly simple integration that crashes mathematica kernel. I'm trying to integrate symbolically the function x Cos[a x] with respect to x, where the factor a can be symbolical or numerical. Integrate[x Cos[a x],x] yields the correct answer: Cos[a*x]/a^2 + (x*Sin[a*x])/a note that this integral is perfectly regular for a->1 Integrate[x Cos[2. x], x] yields again the correct answer: 0.25 Cos[2. x] + 0.5 x Sin[2. x] Integrate[x Cos[x], x] yields again the correct answer: Cos[x] + x Sin[x] However, Integrate[x Cos[1. x], x] crashes the kernel, and it's impossible to abort or interrupt the calculation, which lasts forever. This bug appears in mathematica 5, but not in mathematica 4. I find it annoying that Integrate[] works for some real values of a, but not for some other ones for which the integral behaves perfectly well. Any remark ?