Re: Possible Bug Report: CoefficientList
- To: mathgroup at smc.vnet.net
- Subject: [mg88861] Re: [mg88844] Possible Bug Report: CoefficientList
- From: Andrzej Kozlowski <akoz at mimuw.edu.pl>
- Date: Mon, 19 May 2008 06:45:08 -0400 (EDT)
- References: <200805190915.FAA12556@smc.vnet.net>
On 19 May 2008, at 18:15, 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. >> > This is not a bug but a question of understanding the way Mathematica evaluates certain expressions; in particular case Table. Chances[dice_, sides_] := CoefficientList[Expand[Sum[x^i, {i, sides}]^dice], x]; Table[Evaluate[Chances[x, 6]], {x, 3, 5}] {{1302170688}, {888731494560000}, {2841261564746499300000}} Note the need for Evaluate. Andrzej Kozlowski PS. Did it not seem to you rather remarkable that a bug as basic as this would survive till version 6 of Mathematica?
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- Re: Re: Possible Bug Report: CoefficientList
- From: Andrzej Kozlowski <akoz@mimuw.edu.pl>
- Re: Re: Possible Bug Report: CoefficientList
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- Possible Bug Report: CoefficientList
- From: anglewyrm@yahoo.com
- Possible Bug Report: CoefficientList