Well... fixed point numbers (aka ScaledDecimals) had their issues as well. And in this particular case, it might cause issues, since the "full precision" (whatever that means) must be retained when using such a number to derive another one.
E.g. in my case: ch := 6.7 + (32.8 - 35). "course handicap" allowance := 0.85. "85%" ph := (ch * allowance) roundedHandicap. "playing handicap" The #roundedHandicap is like #rounded but rounds -0.5 towards -1 instead of toward 0. My first approach was to use fixed points, but then I hit issues where some results also produced "wrong" numbers (according to the reference), also in Pharo some ScaledDecimals compare as different even when they're printed as the same (which is not correct, IMO). I just tested using everything as fractions and converting to float (or ScaledDecimal) at the very last step and it produces the expected result. I'll review and convert whatever is needed (including database fields) to work with this. The good thing is that all the involved numbers only have one decimal as much. Thanks! Esteban A. Maringolo On Tue, Jun 15, 2021 at 3:48 AM Steffen Märcker <merk...@web.de> wrote: > > Have you considered using fixed-point arithmetic? For example: > 7.1s2 roundTo: 0.1s2 > > The rule of thumb I stick to is to use FP only if I know the inaccuracies > won't bite me. Funny enough, both 7.1 and 0.1 are already not accurately > representable as floats. (And by coincidence, I prepared exam questions > about floats for my students yesterday. ) > > Kind regards, > Steffen > > > Konrad Hinsen schrieb am Dienstag, 15. Juni 2021 07:02:30 (+02:00): > > > On 15/06/2021 01:03, Esteban Maringolo wrote: > > > Sure, but what initiated this thread was a reference to roundTo: 0.1 > > > which produced a "wrong" output. > > > > > > (9.1 + (-2.0)) roundTo: 0.1 "=> 7.1000000000000005" > > > 7.1 roundTo: 0.1 "=> 7.1000000000000005" > > > > > > However, at this point I know that Pharo "does the right, raw, thing" > > > (at least compared to other mainstream languages), but it still > > > produces a surprise effect. > > > > That's the "floating point surprise" that everyone has at some point, no > matter the language and runtime system. If that surprise is a problem for > you, are you sure that floating-point arithmetic is what you really want? > Maybe your needs are better served with integers and fractions. > > > > > > Konrad. > > > > > -- > Gesendet mit Vivaldi Mail. Laden Sie Vivaldi kostenlos von vivaldi.com > herunter.
