Re: Possible Bug Report: CoefficientList

*To*: mathgroup at smc.vnet.net*Subject*: [mg88876] Re: Possible Bug Report: CoefficientList*From*: dh <dh at metrohm.ch>*Date*: Tue, 20 May 2008 02:26:09 -0400 (EDT)*References*: <g0rker$dte$1@smc.vnet.net>

Hi, consider the variable x in the definition of Chances. This is a global variable that can be changed by anybody, what is very dangerous. This is exactly what happens in Table[...]. You must localize this variable e.g. using Module. Hope this helps, Daniel anglewyrm at yahoo.com wrote: > Here is a function using CoefficientList[] that produces a list: > Chances[dice_, sides_] := CoefficientList[Expand[(Sum[x^i, {i, > sides}])^dice], x]; > > (* This works: *) > Chances[3, 6] > Chances[4,6] > Chances[5,6] > > (* This fails: *) > Table[ Chances[x, 6], {x, 3, 5}] > > CoefficientList::ivar: 1 is not a valid variable. >> > CoefficientList::ivar: 2 is not a valid variable. >> > CoefficientList::ivar: 3 is not a valid variable. >> > General::stop: Further output of CoefficientList::ivar will be > suppressed during this calculation. >> >