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Re: The side-effects of mixing TraditionalForm inside expressions.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg110790] Re: The side-effects of mixing TraditionalForm inside expressions.
  • From: Andrzej Kozlowski <akozlowski at gmail.com>
  • Date: Tue, 6 Jul 2010 05:03:38 -0400 (EDT)
  • References: <201007051002.GAA15102@smc.vnet.net>

This information is very misleading because what you have observed has 
nothing in particular to do with TraditionalForm. To see that, replace 
TrditionalForm with InputForm or StandardForm and see what happens.
All these "forms" are meant only for the purpose of formatting and 
should not be used inside computations as they are not stripped of after 
evaluation (as, for example, Unevaluted is).

E.g:

1 + InputForm[1]

1+1

FullForm[%]

Plus[1,InputForm[1]]

vs

1 + Unevaluated[1]

 2

Andrzej Kozlowski





On 5 Jul 2010, at 19:02, Nasser M. Abbasi wrote:

>
> FYI,
>
> When I typed the following:
>
> -----------------------------
> Clear[z]
> c = 1 + I; p = -9 + 3*I; t = 3.3;
> d = 1 - Exp[t*p]/z;
>
> expr1 = c/TraditionalForm@d;
> expr2 = c/d;
>
> (expr1 - expr2) /. z -> 1
> --------------------------------
>
> I was expecting to get ZERO, as I do when I do not use TraditionalForm,
> but instead got:
>
> (-0.9999999999999455 - 0.9999999999998298*I) + (1 + I)/
>    1.0000000000001124` + 5.779350816615805`*^-14 I
>
> Then I read in the help for TraditionalForm
>
> "Output from TraditionalForm cannot necessarily be given as unique and
> unambiguous input to Mathematica"
>
> And the above seems to explain this result. Too bad, because I wanted to
> use TraditionalForm inside an expression to format parts of it using a
> function which requires this wrapper.
>
> My lesson of the day: do not use TraditionalForm inside expressions.
>
> --Nasser
>
>



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