You can use github.com/robaho/fixed > On Dec 6, 2019, at 10:19 AM, Michael Jones <michael.jo...@gmail.com> wrote: > > > Agree with Ian. > > Solutions are: change expectations, use decimal floating point, or use a > base-independent decimal representation. The latter implies scaled integers. > > Quick, ugly, and typed on one hand from bed, but here it is: > https://play.golang.org/p/fBztRY6qHP0 > > 999000/1000 = 999.0 > 999050/1000 = 999.1 > 999100/1000 = 999.1 > 999150/1000 = 999.2 > 999200/1000 = 999.2 > 999250/1000 = 999.3 > 999300/1000 = 999.3 > 999350/1000 = 999.4 > 999400/1000 = 999.4 > 999450/1000 = 999.5 > 999500/1000 = 999.5 > 999550/1000 = 999.6 > 999600/1000 = 999.6 > 999650/1000 = 999.7 > 999700/1000 = 999.7 > 999750/1000 = 999.8 > 999800/1000 = 999.8 > 999850/1000 = 999.9 > 999900/1000 = 999.9 > 999950/1000 = 1000.0 > -999950/1000 = -1000.0 > -999900/1000 = -999.9 > -999850/1000 = -999.9 > -999800/1000 = -999.8 > -999750/1000 = -999.8 > -999700/1000 = -999.7 > -999650/1000 = -999.7 > -999600/1000 = -999.6 > -999550/1000 = -999.6 > -999500/1000 = -999.5 > -999450/1000 = -999.5 > -999400/1000 = -999.4 > -999350/1000 = -999.4 > -999300/1000 = -999.3 > -999250/1000 = -999.3 > -999200/1000 = -999.2 > -999150/1000 = -999.2 > -999100/1000 = -999.1 > -999050/1000 = -999.1 > >> On Fri, Dec 6, 2019 at 2:31 AM Ian Davis <m...@iandavis.com> wrote: >>> On Fri, 6 Dec 2019, at 9:25 AM, Christophe Meessen wrote: >>> I have noticed that printf performs an apparently inconsistent rounding of >>> floating point values. >>> >>> I divide a big number by 1000 and printf the resulting value with "%.1f". >>> Here is the code: https://play.golang.org/p/e7dD3c6IHq2 >> >> I think you are just seeing the usual problems of floating point >> representation. >> >> You may wonder why 999450/1000=999.45, 999500/1000=999.50 and >> 999550/1000=999.55 all format as 999.5. The answer is that the internal >> representation of the three results cannot correspond to the mathematical >> result you expect. >> >> This link shows the internal representation of each answer: >> https://play.golang.org/p/bBTNCdsAttR >> >> You can see that 999550/1000 = >> 999.549999999999954525264911353588104248046875 which is printed as 999.5 >> >> >>> I would expect the rounding rule to be "round away from zero" as defined >>> here: https://math.stackexchange.com/a/2252888/33796 >>> In this case 0.5 is rounded to 1 (or 0.05 to 0.1) and -0.5 to -1 (or -0.05 >>> to -0.1). >> >> The strconv and fmt packages use round to even as a rule. Use math.Round to >> round away from zero. >> >> -- Ian >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "golang-nuts" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to golang-nuts+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/ee94624c-5485-4daf-98ad-8e59055056dd%40www.fastmail.com. > > > -- > Michael T. Jones > michael.jo...@gmail.com > -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to golang-nuts+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CALoEmQy%3DMCWgb69GgsZwAv2GT4ar%3DWrdvn212sFK1PfGES1ijw%40mail.gmail.com.
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