       Re: Partial derviatives in mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg95767] Re: Partial derviatives in mathematica
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Mon, 26 Jan 2009 06:49:45 -0500 (EST)
• Organization: The Open University, Milton Keynes, UK
• References: <glk1na\$los\$1@smc.vnet.net>

```In article <glk1na\$los\$1 at smc.vnet.net>, xareon at gmail.com wrote:

[snip]

> jacobian[{x_, y_}] = Transpose[{\[PartialD]x F[{x, y}], \[PartialD]y F
> [{x, y}]}];
>
> Mathematica's kernel warns me with this message when i try to insert
> it:
>
> Code:
>
> Syntax::sntxf: "jacobian[{x_, y_}] = Transpose[{" cannot be followed
> by
>     "\[PartialD]x F[{x, y}], \[PartialD]y F[{x, y}]}];".

[snip]

On my system (v6.0), I have got the more meaningful message:

"Derivative::novar: ?x cannot be interpreted. A partial derivative \
requires a subscript differentiation variable. >>"

The variable must passed as a *subscript* (shortcut Ctrl+-, control +
dash keys) to the symbol partial d.

In:= F[{x_, y_}] = {f1[{x, y}], f2[{x, y}]};

In:= jacobian[{x_,y_}]=Transpose[{\!\(
\*SubscriptBox[\(?\), \(x\)]\ \(F[{x, y}]\)\),\!\(
\*SubscriptBox[\(?\), \(y\)]\ \(F[{x, y}]\)\)}];

(* jacobian[{x_, y_}] = Transpose[{D[F[{x, y}], x], D[F[{x, y}], y]}]; *)

In:= MatrixForm[jacobian[{x, y}]]

Out//MatrixForm=

({1, 0})             ({0, 1})
f1        [{x, y}]   f1        [{x, y}]

({1, 0})             ({0, 1})
f2        [{x, y}]   f2        [{x, y}]

Regards,
--Jean-Marc

```

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