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Re: numeri

From: David De La Harpe Golden
Subject: Re: numeri
Date: Sat, 29 Nov 2008 19:01:22 +0000
User-agent: Mozilla-Thunderbird (X11/20081018)

Eli Zaretskii wrote:

Actually, why not make the above return the number 4?  The Unicode
Data File Format says that this property's value is ``an integer or
rational number''.  We could even use 0.2 for characters such as
"VULGAR FRACTION ONE FIFTH".  Isn't that better than `1/5'?

Bear in mind that 1/5 (0.2) isn't actually exactly representable by binary floating point, bit like the way 1/3 (0.333(3 recurring)) can't be written properly in decimal, so try in emacs lisp:

(format "%.20f" 0.2)

I'd tend to hold off on allowing the vulgar fractions to map to numbers without the programmer to do a conversion step and "own" the associated potential information loss - at least until there is no loss: Emacs Lisp could one day get CL-like exact rational numbers I guess (though bignums would probably be a higher priority...)

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