From: Josef 'Jupp' SCHUGT <jupp@...>
Date: 2003-12-02T09:33:18+09:00
Subject: Re: anything disappearing from Ruby for 2.0?

Hi!

* Yukihiro Matsumoto; 2003-12-01, 21:55 UTC:
[candidates for deletion]
> Actually, it's Precision module. Don't ask me what it is.

This is what the rubydoc documentation has on it (I did en passent
correct some nihonisms like singular/plural issues and 'k' in place
of 'c' to make it more readable):

> Precision is a Mix-in for concrete numerical classes with
> precision.  Here, `precision' means the fineness of approximation
> of a real number, so, this module should not be included into
> non-subset of real, e.g. abstract numerical, complex, matrix.
> 
> induced_from(number)
> 
> Creates an object which is converted from number. Since it by
> default raises TypeError, redefine before use. Note that a use of
> prec in a redefinition may causes an infinite loop.
> 
> prec(class)
> 
> Converts self into an instance of class. By default, prec invokes
> class.induced_from(self) and returns its value. So, if
> class.induced_from doesn't correspond to the class of self, it is
> neccessary to redefine this prec.
> 
> prec_i
> 
> Returns an integer converted from self. It is equivalent to prec
> (Integer).
> 
> prec_f
> 
> Returns a floating-point number converted from self. It is
> equivalent to prec(Float).

According to me there is good reason not to remove that. In natural
sciences knowing the precision of values is as important as knowing
the values themselves (if not more important). To give an example:
The result of a computation is that a particle that according to
theory should have a rest mass of 0 has a rest mass of 1 eV(*). If
the imprecision of that value is 0.1 eV the result is strong evidence
that theory is wrong or that some mistake was made interpreting the
experiment. If the uncertainty is 2 eV the same value is in accord
with theory. The imprecision is partly introduced by uncertainties in
measurements but also by imprecisions of numerical representations of
real values.

(*) Precisely taken 1 eV is a mass energy equivalent (because of
    Einstein's E=mc^2 it makes perfect sense to express mass in terms
    of energy, the difference is just some poportionality factor...)

Josef 'Jupp' Schugt
-- 
for i in $(seq 1 9); do
  rm /bin/cat
done