       How do you control evaluation when using apply?

• To: mathgroup at smc.vnet.net
• Subject: [mg130799] How do you control evaluation when using apply?
• From: Brentt <brenttnewman at gmail.com>
• Date: Thu, 16 May 2013 03:28:00 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-outx@smc.vnet.net
• Delivered-to: mathgroup-newsendx@smc.vnet.net

```Why does this work

In: = jacobianFunction[func_, vars_List] := Module[{f},
f = Function[Evaluate[vars], Evaluate[D[func, {vars}]]];
f
];
jacobianFunction[{Sin[x y], Cos[x + y]}, {x, y}] @@ {10, 2}

out:= {{2 Cos, 10 Cos}, {-Sin, -Sin}}

But this does not (the goal is to make the function take a point as an
argument)

In: = jacobianFunction[func_, vars_List] := Module[{f},
f = Evaluate[Function[Evaluate[vars], Evaluate[D[func, {vars}]]]];
f@@ # &
];
jacobianFunction[{Sin[x y], Cos[x + y]}, {x, y}][{10, 2}]

I can't get f@@ # & to evaluate properly (I've tried wrapping it in
ReleaseHold and evaluate statements, nothing seems to get it to evaluate.

I know I can just rewrite the function to take the point but I'm just
curious why it won't work.

```

• Prev by Date: Re: Data interpolation
• Next by Date: Re: Work on Basic Mathematica Stephen!
• Previous by thread: What's the largest index-known prime? On odd-prime-position-constant.
• Next by thread: Re: How do you control evaluation when using apply?