MathGroup Archive 1994

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Re: Special Input Forms

  • To: mathgroup at, wasfy at
  • Subject: Re: Special Input Forms
  • From: bert at (Roberto Sierra)
  • Date: Mon, 10 Jan 1994 01:21:04 -0800

Does anyone know how to make shorthand input forms in Mathematica?
Specifically, I would like an expression like the

  2 +/- 3

to evaluate to


You're talking about adding new shorthands to the MMA parser.
To the best of my knowledge, this is not possible at the input
prompt level.  The best you might do is to play games with
object rules, for instance, by defining +/-3 as the 'object'
UncertainInteger[3], and then making a rule so that

	2 + UncertainInteger[3]

reduces to


(similarly, 2 - UncertainInteger[3] would give the same answer).

If you *really* want to be able to use the syntax 2 +/- 3, you're
going to have to write your own parser (either external to MMA,
or through an MMA function like MyParser[s_String]) that would
catch the '+/-' cases and convert them to Uncertainty function
calls.  Given the complexity of the precedence rules for MMA's
language syntax, I think this will be a waste of effort.

 \\|//                         "An intellectual carrot...
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   J   roberto sierra
   O   tempered microdesigns    NOTICE:
  \_/  san francisco, ca        The ideas and opinions expressed
       bert at          herein are not those of the author.

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