Re: Phix, numbers, printf, log10
- Posted by petelomax 2 months ago
- 781 views
%f has a "5" rounding issue, this too happens with all kinds of numbers and any number of decimal digits (also happens with Euphoria, as far as I can remember):
printf(1, "%0.1f", 2.75)
2.8 rounding up
printf(1, "%0.1f", 2.85)
2.8 rounding down
Ah, the problem here is that 2.85 cannot be held exactly, and the nearest IEEE-754 representation is ~2.849999999999999999 which is correctly rounded down.
You might be able to do something with rationals, otherwise that's a fundamental and unsolveable hardware issue. [At least now I can start on the first three.]
PS I stumbled on what might be a fairly nifty magnitude() function, but it needs the range of values it must cope with, from you, and probably a bit of polishing, before I can post it.
Update: I've now got a fix for the first part ("%e" was not updating f the same way "%f" does as it printed digits):
digit = floor(f) --21/2/24: f = (f-digit)*10
and
--21/2/24 -- f = (f-digit)*10 digit = floor(f) f = (f-digit)*10
Many thanks. I'd recommend running "p -test" after editing that in and running "p -cp", to make sure nothing got broken.
