Re: Difference table via DifferenceDelta[ ]. Why do I need two Table[ ] calls?

*To*: mathgroup at smc.vnet.net*Subject*: [mg121174] Re: Difference table via DifferenceDelta[ ]. Why do I need two Table[ ] calls?*From*: Christopher Young <cy56 at comcast.net>*Date*: Fri, 2 Sep 2011 03:29:37 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <j3l6l1$d81$1@smc.vnet.net> <19D39C6A71784A0E827D1B556E9B2EBF@microsof8970a2>

Thanks, I'll be wary of DifferenceDelta. Looks like Differences will work just as well for me here. On Sep 1, 2011, at 11:08 AM, Alexey Popkov wrote: > Christopher, > > DifferenceDelta is an autoloaded function: > > In[1]:= ClearAttributes[DifferenceDelta, {Protected, ReadProtected}] > Definition[DifferenceDelta] > Out[2]= DifferenceDelta := > System`Dump`AutoLoad[Hold[DifferenceDelta], Hold[DifferenceDelta], > Discrete`DifferenceDelta`] /; System`Dump`TestLoad > > The need for Evaluate in your code is an inconsistency: such code should > work well without beating the HoldAll attributes of Table. And error > messages when your code is evaluated without Evaluate clearly show very bad > design of this function. I recommend do not rely on such functions. > > As for why you have to evaluate your code twice, you may be interested in > this thread: > http://stackoverflow.com/questions/5649379/why-do-i-have-to-evaluate-this-twice > > > Alexey Chris Young cy56 at comcast.net