Re: ZTarnsform[Sin[4 n],n,z] OK, but ZTransform[Sin[5 n],n,z,] hangs?

*To*: mathgroup at smc.vnet.net*Subject*: [mg56805] Re: ZTarnsform[Sin[4 n],n,z] OK, but ZTransform[Sin[5 n],n,z,] hangs?*From*: Peter Pein <petsie at dordos.net>*Date*: Fri, 6 May 2005 03:00:37 -0400 (EDT)*References*: <d5cth5$mbe$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

steve wrote: > Hello; > This is Mathematica 5.1 on windows. > > This is a strange one. > > When I start Mathematica and type > > ZTarnsform[Sin[4 n],n,z] > > Then I get the answer. > > but if replace '4' by '5' above, I see Mathematica starts > to consume huge amount of memory untill the PC hangs running > out of virtual RAM. > > ZTarnsform[Sin[5 n],n,z] <---- hangs > ZTarnsform[Sin[4 n],n,z] <---- ok > > any one has any idea what is going on? is this some subtle > mathemtical thing I am overlooking that is causing this? > what is so special about '5' here? > > thanks, > Steve > Hi Steve, I don't know, what happens in the kernel, but ZTransform[Sin[a n], n, z] /. a -> 5 gives a quick answer. -- Peter Pein Berlin