Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2010

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

Search the Archive

Re: Replacement Rule with Sqrt in denominator

  • To: mathgroup at smc.vnet.net
  • Subject: [mg114520] Re: Replacement Rule with Sqrt in denominator
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Mon, 6 Dec 2010 06:14:21 -0500 (EST)

On 12/5/10 at 9:52 PM, fateman at cs.berkeley.edu (Richard Fateman)
wrote:

>On 12/4/2010 3:14 AM, Bill Rowe wrote:

>>When an aspect of software works as designed it is inappropriate to
>>refer to that aspect as a bug.

>OK, I say "Dressing up a bug as a feature does not fix the bug."

And I agree.

>You say, in effect,

>If a designer writes a program that does exactly what the designer
>intended, then it is not a bug.

Yes.

>OK, then, what term do you wish to use to refer to the result of
>design and programming that results from an error in the design

I don't agree the behavior of replacement rules reflects an
error in design.

>that causes mathematical computations to proceed in a way that is
>internally inconsistent, and is generally considered mathematical
>nonsense?

Since replacement rules are not doing mathematics there should
be no requirement for the result to make mathematical sense.
That is a replacement rule such as 2->1 is perfectly valid but
clearly doesn't make 2 equal to 1.

>>The fact replacement rules operate on the FullForm of an expression
>>but what is displayed is not the FullForm does mean inexperienced
>>users of Mathematica will encounter some difficulties with
>>replacement rules. But, that simply doesn't equate to being a bug.

>No, I think the error is that users need to have another kind of
>pattern matching, and that when too many people stumble over the
>same feature, the correct response is NOT, "the customer is wrong,
>yet again."

>It might be ,  Oh, you want the semantic pattern matcher.
>Maybe, Here's how we can set it up to be your default command pattern
>matcher...

In another post Daniel Lichtblau described the issues with
trying to make replacement rules work on what is displayed
rather than full form.



  • Prev by Date: Re: Counting number of numbers in a large list between two valus
  • Next by Date: Re: Re-virginating Manipulates?
  • Previous by thread: Re: Replacement Rule with Sqrt in denominator
  • Next by thread: Re: Replacement Rule with Sqrt in denominator