Re: Evaluating expressions in pure functions
- To: mathgroup at smc.vnet.net
- Subject: [mg28459] Re: [mg28453] Evaluating expressions in pure functions
- From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
- Date: Fri, 20 Apr 2001 04:24:10 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
on 01.4.19 4:26 PM, Max Ulbrich at ulbrich at biochem.mpg.de wrote:
> Hi,
>
> I have the following problem:
> I have a pure function with a product of numbers in it.
> Mathematica doesn't evaluate the product:
>
> Exp[2*3*#]&
>
> I just want to get
>
> Exp[6*#]&
>
> How can I make Mathematica do this?
> Thanks,
>
> Max
>
>
>
The reason why this happens is that
In[6]:=
Exp[2*3*#] & // FullForm
Out[6]//FullForm=
Function[Exp[Times[2, 3, Slot[1]]]]
and
In[7]:=
Attributes[Function]
Out[7]=
{HoldAll, Protected}
To overcome this you have to force Function to evaluate its arguments, e.g.
In[8]:=
Evaluate[Exp[2*3*#]] &
Out[8]=
6 #1
E &
The problem is, it seems rather quicker just to enter 6 in the first
place...
--
Andrzej Kozlowski
Toyama International University
JAPAN
http://platon.c.u-tokyo.ac.jp/andrzej/
http://sigma.tuins.ac.jp/