[fpc-pascal] Re: StrUtils.RomanToInt oddities

[Frederic Da Vitoria]

2013/9/24 Reinier Olislagers <reinierolislagers at gmail.com>

> On 23/09/2013 23:34, Alberto Narduzzi wrote:
> >> I don't believe though Romans knew negative numbers.
> Well, they could subtract, couldn't they :)
>
> >> But I'm certainly not an expert on the matter.
> >
> > never though about, but if the only matter is DEBT, then just write
> > positive numbers under the DEBT column, and everybody shall be happy
> > too, provided they know the meaning of such a column ;-)
> You just described an alternative indication of a negative number...
> only instead of a minus sign, you use column position as an indicator ;)
> To calculate net equity, you'd still have to subtract the debts from the
> possessions, i.e. deal with the debt as negative numbers.
>

Not quite. The mathematical result would be the same, but try explaining
what a negative number is to a kid :-) You may have forgotten it, but there
was a time when you had to be explained that a - b = a + (-b) (which is not
exactly using a negative number but closely related to it). In the above
example, the debt is to be subtracted, this does not automatically trigger
the abstract concept of negative number in the user's mind. I even think
that if the romans really had the concept of negative numbers, they would
have devised a notation for it allowing them to include them in texts. Does
such a notation exist?


 > P.S. Have no clue of roman arithmetics, thou', which looks a little
> > more weird to implement, or just to think about :-O
>
> I would be very careful in definining too many restrictions on what you
> accept as Roman numerals as the number of fixed rules is rather small
> and there are a lot of exceptions, especially in later years (i.e.
> Bart's example of bigger numbers).
> In other words, the system of Roman numerals was not fixed; it changed
> over time, it was mostly based on conventions that fell short of actual
> rules.
>

You are probably right: see
http://www.web40571.clarahost.co.uk/roman/howtheywork.htm

-- 
Frederic Da Vitoria
(davitof)

Membre de l'April - « promouvoir et défendre le logiciel libre » -
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