Re: Re: Re: Re: Mathematica language issues
- To: mathgroup at smc.vnet.net
- Subject: [mg53158] Re: [mg53142] Re: [mg53112] Re: [mg53050] Re: Mathematica language issues
- From: DrBob <drbob at bigfoot.com>
- Date: Mon, 27 Dec 2004 06:41:28 -0500 (EST)
- References: <200412241058.FAA05777@smc.vnet.net> <200412250900.EAA18524@smc.vnet.net> <97F219DA-567C-11D9-8E89-000A95B4967A@mimuw.edu.pl>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
>> If Fred's "speculations" came form an employee of WRI they could >> have the status of "documentation" without changing a word. The >> mystery here is simply a question of authoritativeness. If he's correct, you mean. Bobby On Sat, 25 Dec 2004 22:55:10 +0900, Andrzej Kozlowski <akoz at mimuw.edu.pl> wrote: > I am sure Fred will provide his own answers, but on the principle "the > more the merrier" (especially at Christmas) , I thought I would > contribute my own comments: > > On 25 Dec 2004, at 18:00, DrBob wrote: > >> Fred, >> >> At several points you made statements I simply don't understand. The >> examples clarify what you meant for the most part, but I'm still >> wondering, so here goes: >> >>>> Unevaluated is meant to pass unevaluated arguments to a function >>>> body and as such it works perfectly. No one in practice is interested >>>> in (1+1)*Unevaluated[2+2]. >> >> Do you mean a Function body? If not, Times in that example qualifies >> as a function body. (I think.) > > One uses Unevaluated to prevent a rule from being applied. This means > that a rational person will only do it when he knows there is a rule > that he does not want to be used. There is no normal situation where > one would use Unevaluated and there was no specific evaluation one > wanted to prevent. > >> >>>> If now no rules for f can be applied, Mathematica returns the result >>>> so far, with Unevaluated wrapped again around the labeled arguments. >> >> So it's only rules FOR F that matter? Does the distributive property >> count as a rule for Times? > > You do not need Unevaluated to prevent the distributive rule being used > because it is never used automatically. You need to apply something > like Distribute etc. > >> >>>> If a rule for f can be applied, the administration of arguments >>>> that come from Unevaluated is completely skipped. >> >> I don't get any meaning from the phrase "administration of arguments". > > I think Fred meant that the rule is applied to the arguments "as > given", without changing them or rearranging in any way. > >> >>>> I first formulate my assumption (only WRI and maybe a few others >>>> know if I am right!) >> >> Even if your assumption is correct (as I suspect it is), this >> statement doesn't really square with a later claim that there's no >> mystery. > > A certian mystery exists even when we have full documentation, because > even that is only a description of expected behaviour of Mathematica > and does not include the actual mechanism behind the behaviour (of > which at most a vague idea is provided). Everything else requires the > source code. If Fred's "speculations" came form an employee of WRI they > could have the status of "documentation" without changing a word. The > mystery here is simply a question of authoritativeness. > > > Andrzej Kozlowski > Chiba, Japan > http://www.akikoz.net/~andrzej/ > http://www.mimuw.edu.pl/~akoz/ > > > > -- DrBob at bigfoot.com www.eclecticdreams.net
- References:
- Re: Re: Re: Mathematica language issues
- From: "Fred Simons" <f.h.simons@tue.nl>
- Re: Re: Re: Mathematica language issues
- From: DrBob <drbob@bigfoot.com>
- Re: Re: Re: Mathematica language issues