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Re: Unprotecting "I"


Thanks very much, I would never have guessed this.

On 2006-03-04 03:25:02 -0500, ted.ersek at tqci.net said:

> A user wanted to Unprotect the symbol I so they could use it for something
> other than Sqrt[-1]. That can't be done because I has the Locked
> attribute. Very few symbols have that attribute. This is only for the ones
> WRI wants to make sure you don't change, but there is still a way to get
> around it! Use the following:
> 
> In[1]:=
>   $PreRead=(#/."I"->"VariableI")&;
>   MakeBoxes[VariableI, form:(StandardForm|TraditionalForm) ]:="I"
> 
> I think you can then use I just like you use {x, y, t, ...}.
> Just beware that this code will make it so that (I) and (VariableI)
> are one and the same.
> 
> Then if you want to use the complex number type
>   [Esc]ii[Esc]   (where [Esc] means press the Esc key.)
> 
> In the event you are using $PreRead for something else, you can probably
> combine the my $PreRead code with yours.
> 
> I think it' possible to get the same result with MakeExpression
> definitions instead of an assignment to $PreRead, but I had trouble
> getting it to work.
> 
> Regards,
>    Ted Ersek


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