Re: how to differentiate a list?

• To: mathgroup at smc.vnet.net
• Subject: [mg25960] Re: [mg25940] how to differentiate a list?
• From: Tomas Garza <tgarza01 at prodigy.net.mx>
• Date: Tue, 14 Nov 2000 03:46:53 -0500 (EST)
• Sender: owner-wri-mathgroup at wolfram.com

I don't think there is a list operation which will accomplish what you
want. However, you  may use

Rest[sd] - Drop[sd, -1]

which a neater way to get your diff.

Tomas Garza
Mexico City

"Rob" <piovere at pdq.net> wrote:

> I needed to get the derivative of a time varying pulse to do some
> numerical
> operations.  As seen below, the only way I could figure how to do it
> was to generate two lists, shifted by one sample and then subtract
them:
>
> ***************
> del = 0.002; a = 12\[Pi]; b = \[Pi];
> ( s[t] is a function of t defining the pulse )
>
> sd = Table[N[s[t]], {t, 0, 1, del}];
> sd1 = Table[N[s[t]], {t, del, 1 + del, del}];
> diff = sd - sd1;
> ****************
>
> I looked all over and I didn't find a list operation available to do
> this. I bet
> you Mathematica gurus know how to do this.  If so, could you enlighten
me?

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