Re: Stupid simple question about counting derivatives

• To: mathgroup at smc.vnet.net
• Subject: [mg33480] Re: Stupid simple question about counting derivatives
• From: "Avraham Shinnar" <as1619 at columbia.edu>
• Date: Fri, 22 Mar 2002 04:07:32 -0500 (EST)
• Organization: Columbia University
• References: <a7crpm\$hu8\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```D[a x,x]

You need a space between the a and the x.
What you have now is a variable ax, and since D takes the partial derivative
w.r.t x, and ax is an unrelated variable, D returns 0.
with the space, (a x) is the same as a*x.
-- Avraham Shinnar

"Jack" <kielczew at poczta.onet.pl> wrote in message
news:a7crpm\$hu8\$1 at smc.vnet.net...
> How do I get Mathematica 2.2 to count the derivatives of the simplest
> parametric functions, i.e.
>
> (ax)', where a is the parameter and x is the variable. I want to get:
>
> a
>
> (Hey, I said it was stupid).
>
> D[ax,x] gets me 0, Dt[ax,x] gets me Dt[ax,x] and I haven't figured out
> how to use Constants and NonConstants. I'd be grateful for any help as
> this simple problem is driving me crazy.
>
>
> --
> Jacek Kie³czewski
> kielczew at poczta.onet.pl
>
>
>
>
>

```

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