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MathGroup Archive 2006

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Re: Is this a BUG of D[f, var1, ..., NonConstants -> {u1, ...}] ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg65214] Re: [mg65186] Is this a BUG of D[f, var1, ..., NonConstants -> {u1, ...}] ?
  • From: Bruce Miller <brucem at wolfram.com>
  • Date: Sat, 18 Mar 2006 06:40:35 -0500 (EST)
  • References: <200603170513.AAA09739@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

This had been reported before, but not in such detail.
A correction is in the works for a future release.

Bruce Miller
Technical Support
Wolfram Research, Inc.
support at wolfram.com
http://support.wolfram.com/



On Mar 16, 2006, at 11:13 PM, wyelen at gmail.com wrote:

> As we all know, when Evaluating the following command:
>
>      D[f[x], t, NonConstants -> {x}]
>
> we should got something like this:
>
>      D[x, t, NonConstants -> {x}] f ' [x]
>
> But there seems to be some particular names in Mathematica, which will
> cause strange things when using as variables.
>
> eg. We expect a result as
>
>      D[g, t, NonConstants -> {g}] f ' [g]
>
> when Evaluate
>
>      D[f[g], t, NonConstants -> {g}]
>
> but in fact Mathematica gives 0.
>
> And let's go further, to run the following code to see more instances.
>
>    (*define a arbitrary function fn's derivative*)
>      Clear[tpf]
>      tpf[mvr_, vr_] := D[fn[mvr], vr, NonConstants -> {mvr}]
>
>    (*we'll calculate derivatives using variables named over this List*)
>      stl = ToExpression[CharacterRange["a", "z"]];
>
>    (*the result-table. you'll find some unexpected and regular zeros.*)
>      dchn = Table[tpf[stl[[lp1]], stl[[lp2]]], {lp1, 26}, {lp2, 26}];
>      TableForm[dchn]
>
>    (*for clear vision*)
>      TableForm[dchn /. D :> (Subscript[#1, #2] & )]
>
> In order to paste the result here, I replaced all of the nonzero
> elements in it with ".", so you can see clearly.
>
> 	  a b c d e f g h i j k l m n o p q r s t u v w x y z
> 	a . . . . . 0 . . . . . . . 0 . . . . 0 . . . . . . .
> 	b . . . . . 0 . . . . . . . . 0 . . . 0 . . . . . . .
> 	c . . . . . 0 . . . . . . . . . 0 . . 0 . . . . . . .
> 	d . . . . . 0 . . . . . . . . . . 0 . 0 . . . . . . .
> 	e . . . . . 0 . . . . . . . . . . . 0 0 . . . . . . .
> 	f . . . . . . . . . . . . . . . . . . 0 . . . . . . .
> 	g . . . . . 0 . . . . . . . . . . . . 0 0 . . . . . .
> 	h . . . . . 0 . . . . . . . . . . . . 0 . 0 . . . . .
> 	i . . . . . 0 . . . . . . . . . . . . 0 . . 0 . . . .
> 	j . . . . . 0 . . . . . . . . . . . . 0 . . . 0 . . .
> 	k . . . . . 0 . . . . . . . . . . . . 0 . . . . 0 . .
> 	l . . . . . 0 . . . . . . . . . . . . 0 . . . . . 0 .
> 	m . . . . . 0 . . . . . . . . . . . . 0 . . . . . . 0
> 	n 0 . . . . 0 . . . . . . . . . . . . 0 . . . . . . .
> 	o . 0 . . . 0 . . . . . . . . . . . . 0 . . . . . . .
> 	p . . 0 . . 0 . . . . . . . . . . . . 0 . . . . . . .
> 	q . . . 0 . 0 . . . . . . . . . . . . 0 . . . . . . .
> 	r . . . . 0 0 . . . . . . . . . . . . 0 . . . . . . .
> 	s . . . . . 0 . . . . . . . . . . . . . . . . . . . .
> 	t . . . . . 0 0 . . . . . . . . . . . 0 . . . . . . .
> 	u . . . . . 0 . 0 . . . . . . . . . . 0 . . . . . . .
> 	v . . . . . 0 . . 0 . . . . . . . . . 0 . . . . . . .
> 	w . . . . . 0 . . . 0 . . . . . . . . 0 . . . . . . .
> 	x . . . . . 0 . . . . 0 . . . . . . . 0 . . . . . . .
> 	y . . . . . 0 . . . . . 0 . . . . . . 0 . . . . . . .
> 	z . . . . . 0 . . . . . . 0 . . . . . 0 . . . . . . .


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