       Re: D[...] change in 5.1

• To: mathgroup at smc.vnet.net
• Subject: [mg58706] Re: D[...] change in 5.1
• From: Alexei Akolzin <akolzine at uiuc.edu>
• Date: Fri, 15 Jul 2005 03:02:22 -0400 (EDT)
• Organization: University of Illinois at Urbana-Champaign
• References: <db57qa\$4ri\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```I am sorry, here what I meant:

In := n /: D[n[i_], x[j_], NonConstants -> n] := (1/r)*(d[i, j] -
n[i]*n[j]);

In := D[n[k], x[l], NonConstants -> n]
Out = (d[k, l] - n[k] n[l]) / r

In := D[1 + n[k], x[l], NonConstants -> n]
Out = D[n, x[l], NonConstants -> n]

In := \$Version
Out = "5.1 for Linux x86 (64 bit) (January 27, 2005)"

From my point of view Out should be exactly equal to Out. It was
in earlier versions, but it is not in 5.1! The difference gives all
kind of problems in more complicated expressions. I try to combat this
with Hold and ReleaseHold, but ran into a more peculiar problem, which
is even more puzzling to me:

In := n /: D[ n[i_], x[j_], NonConstants -> {n, r} ] := ( \[Delta][i,
j] - n[i] n[j]) / r;
In := r /: D[ r, x[i_], NonConstants -> {n,r} ] := n[i];

In := D[ \[Delta][i,j] BesselJ[0 , k r] , x[l], NonConstants ->
{n,r} ]
Out = 0

In := D[ \[Delta][i,j] BesselJ[0 , k r] , x[m], NonConstants ->
{n,r} ]
Out = - k BesselJ[1,k r] n[m] \[Delta][i,j]

In := ?k
Global`k

In:= ? \[Delta]
Global`\[Delta]

Now, Out and Out should be the simmilar. The only difference is
what simbol "m"  or "l" is used in respective differentiation by x[m]
or x[l]. But again they are not. The problem disappears if I substitute
"\[Delta]", which I enter from keyboard as Esc d Esc, for example by
"d".

Sincerely,
Alexei.

```

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