Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Re: What is the purpose of the Defer Command?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82147] Re: [mg82122] Re: What is the purpose of the Defer Command?
  • From: DrMajorBob <drmajorbob at bigfoot.com>
  • Date: Sat, 13 Oct 2007 03:52:56 -0400 (EDT)
  • References: <fe4uhp$155$1@smc.vnet.net> <fefhui$j6c$1@smc.vnet.net> <1721082.1192176923906.JavaMail.root@m35>
  • Reply-to: drmajorbob at bigfoot.com

How about this?

Function[{n},
    Print[save[n] = HoldForm[Integrate[x^n Exp[-x], {x, 0, 1}]]]] /@
   Range[5];

That gives the same outputs as the Defer example and it allows, for  
instance,

save[3] // ReleaseHold

6 - 16/\[ExponentialE]

We can use Defer almost the same way, however:

Function[{n},
    Print[save[n] = Defer[Integrate[x^n Exp[-x], {x, 0, 1}]]]] /@
   Range[5];

First@save[3]

6 - 16/\[ExponentialE]

Bobby

On Fri, 12 Oct 2007 02:04:49 -0500, Vince Virgilio <blueschi at gmail.com> 
wrote:

> On Oct 9, 5:34 am, "David Park" <djmp... at comcast.net> wrote:
>> Still, my question is: "What is the purpose of the Defer Command?"
>>
>> The only potential purpose that I can see is for didactic purposes, to  
>> show
>> preliminary expressions before they are automatically evaluated. But the
>> only way to get Defer to evaluate is by copying and pasting and then
>> evaluating,  by using Shift-Ctrl-L and then evaluating, or by  
>> evaluating in
>> place. All of these operations leave no record of the steps taken. That  
>> goes
>> contrary to any didactic purpose.
>>
>> --
>> David Park
>> djmp... at comcast.nethttp://home.comcast.net/~djmpark/
>
> Have you noticed the example in the documentation (http://
> reference.wolfram.com/mathematica/ref/Defer.html) that uses Defer to
> create cells with unevaluated contents? That has didactic potential.
>
> Can that example be rewritten without Defer, with similar complexity?
>
> Vince Virgilio
>
>
>



-- 

DrMajorBob at bigfoot.com


  • Prev by Date: Inset a 3D Graphic
  • Next by Date: Re: HELP: How to do count to the SUB-LIST
  • Previous by thread: Re: What is the purpose of the Defer Command?
  • Next by thread: Re: Re: What is the purpose of the Defer Command?