Re: Better way to test the number of arguments?

• To: mathgroup at smc.vnet.net
• Subject: [mg132643] Re: Better way to test the number of arguments?
• From: Bob Hanlon <hanlonr357 at gmail.com>
• Date: Sun, 27 Apr 2014 21:43:43 -0400 (EDT)
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• References: <20140427064225.DB5346A1C@smc.vnet.net>

```ddSaPartial[f][args__]  := D[f[args],  {Rest@{args}}]

Bob Hanlon

2014-04-27 2:42 GMT-04:00 <pgeipi10 at gmail.com>:

> Hi,
>
> I have the following code that produces the gradient of a function (with
> respect to all but the first variable). There is probably a better way that
> avoids the Switch.
>
> Thank you,
>
> Pavel
>
> ddSaPartial[func_][t_, s__] := Switch[Length[{s}],
>   1, {Derivative[0, 1][func][t, s]},
>   2, {Derivative[0, 1, 0][func][t, s],
>    Derivative[0, 0, 1][func][t, s]},
>   3, {Derivative[0, 1, 0, 0][func][t, s],
>    Derivative[0, 0, 1, 0][func][t, s],
>    Derivative[0, 0, 0, 1][func][t, s]},
>   4, {Derivative[0, 1, 0, 0, 0][func][t, s],
>    Derivative[0, 0, 1, 0, 0][func][t, s],
>    Derivative[0, 0, 0, 1, 0][func][t, s],
>    Derivative[0, 0, 0, 0, 1][func][t, s]},
>   5, {Derivative[0, 1, 0, 0, 0, 0][func][t, s],
>    Derivative[0, 0, 1, 0, 0, 0][func][t, s],
>    Derivative[0, 0, 0, 1, 0, 0][func][t, s],
>    Derivative[0, 0, 0, 0, 1, 0][func][t, s],
>    Derivative[0, 0, 0, 0, 0, 1][func][t, s]}
>
>
>
>

```

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