Re: Re: Re: "At long last, Sir, have you no shame?"

*To*: mathgroup at smc.vnet.net*Subject*: [mg18604] Re: [mg18551] Re: [mg18524] Re: "At long last, Sir, have you no shame?"*From*: "Andrzej Kozlowski" <andrzej at tuins.ac.jp>*Date*: Tue, 13 Jul 1999 01:01:31 -0400*Sender*: owner-wri-mathgroup at wolfram.com

Note the following. In[1]:= g = Exp[-i]; In[2]:= Sum[g, {i, 1, n}] Out[2]= n -- i E In[3]:= Product[g, {i, 1, n}] Out[3]= -(1/2) n (1 + n) E In[4]:= Attributes[Sum] Out[5]= {HoldAll, Protected, ReadProtected} In[5]:= Attributes[Product] Out[6]= {HoldAll, Protected, ReadProtected} -- Andrzej Kozlowski Toyama International University JAPAN http://sigma.tuins.ac.jp http://eri2.tuins.ac.jp ---------- >From: "Kevin J. McCann" <kevinmccann at Home.com> To: mathgroup at smc.vnet.net >To: mathgroup at smc.vnet.net >Subject: [mg18604] [mg18551] Re: [mg18524] Re: "At long last, Sir, have you no shame?" >Date: Sat, Jul 10, 1999, 3:18 PM > > I agree, the Mathematica answer is *clearly* nonsense, and for wri to claim > otherwise because "Sum has attribute HoldAll" indicates that that person is > more fascinated with the software than the purpose that the users have for > purchasing it. I did not purchase Mathematica because of this "feature", rather to > solve problems. The most insidious thing about such bugs is that they may > not be so obvious in a complex piece of analysis. > > Kevin > > ----- Original Message ----- > From: Colin Rose <colin at tri.org.au> To: mathgroup at smc.vnet.net > To: mathgroup at smc.vnet.net > Subject: [mg18604] [mg18551] [mg18524] Re: "At long last, Sir, have you no shame?" > > >> >> David Withoff <withoff at wolfram.com> wrote: >> >> >> > independent experts often disagree about what is or is not a bug. >> >> >> >> Two cases instantly come to mind: >> >> >> 1. Sum in v4 >> _________ >> >> Consider say: >> >> In[1]:= g = Exp[-i]; >> >> >> In[2]:= Sum[g, {i, 1, n}] >> >> Out[2]= n/E^i >> >> which is nonsense. This happens for almost ANY expression g=g(i). >> To get the correct answer, you have to wrap Evaluate around g: >> >> In[3]:= Sum[Evaluate[g], {i, 1, n}] >> Out[3]= (-1 + E^n)/(E^n*(-1 + E)) >> >> Wolfram support says Out[2] is not a bug, since Sum has attribute HoldAll. >> I say it is clearly (and obviously) an extremely serious bug, >> in the sense that it gives the wrong answer to almost any Summation >> where g is pre-defined. I reported it under v4 alpha, it was fixed >> in the betas, and it is now back in the v4 final release. But then >> it isn't a bug, apparently !? >> >> > >