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MathGroup Archive 2005

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Re: Baffling change to partial derivative in version 5.1

  • To: mathgroup at smc.vnet.net
  • Subject: [mg61584] Re: [mg61555] Baffling change to partial derivative in version 5.1
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 23 Oct 2005 05:45:48 -0400 (EDT)
  • Reply-to: hanlonr at cox.net
  • Sender: owner-wri-mathgroup at wolfram.com

{$Version,$ReleaseNumber}

{5.2 for Mac OS X (June 20, 2005),0}

I have the same problem, but only certain variable names cause the problem

{#, D[x y, #, NonConstants -> {x}]}& /@
    {t, ti, tim, time, timed, l, li, liv, live, lived}

{{t, y*D[x, t, NonConstants -> {x}]}, 
  {ti, y*D[x, ti, NonConstants -> {x}]}, 
  {tim, y*D[x, tim, NonConstants -> {x}]}, {time, 0}, 
  {timed, 0}, {l, 0}, {li, 0}, {liv, 0}, 
  {live, y*D[x, live, NonConstants -> {x}]}, 
  {lived, y*D[x, lived, NonConstants -> {x}]}}


Bob Hanlon

> 
> From: Steven HANCOCK <Steven.Hancock at cern.ch>
To: mathgroup at smc.vnet.net
> Date: 2005/10/22 Sat AM 12:35:59 EDT
> Subject: [mg61584] [mg61555] Baffling change to partial derivative in version 5.1
> 
> Please, can anyone explain (or even just reproduce) the following 
behaviour?
> 
> 
> In[1]:=
> $Version
> 
> Out[1]=
> 5.1 for Microsoft Windows (October 25, 2004)
> 
> In[2]:=
> $ReleaseNumber
> 
> Out[2]=
> 0
> 
> In[3]:=
> D[x y, t, NonConstants->{x}]
> 
> Out[3]=
> y D[x, t, NonConstants -> {x}]
> 
> In[4]:=
> D[x y, time, NonConstants->{x}]
> 
> Out[4]=
> 0
> 
> 
> Merely changing the spelling of the variable from t to time does not 
> return zero in version 4.2.
>                              Thanks, Steve.
> 
> 


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