https://play.golang.org/p/j5HKxitS-Z6
See https://0.30000000000000004.com/ On Friday, December 6, 2019 at 1:25:01 AM UTC-8, 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 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). > > Here is what I see with golang 1.13.4: > > 999000/1000 = 999.0 > 999050/1000 = 999.0 // expected 999.1 > 999100/1000 = 999.1 > 999150/1000 = 999.1 // expected 999.2 > 999200/1000 = 999.2 > 999250/1000 = 999.2 // expected 999.3 > 999300/1000 = 999.3 > 999350/1000 = 999.4 > 999400/1000 = 999.4 > 999450/1000 = 999.5 > 999500/1000 = 999.5 > 999550/1000 = 999.5 // expected 999.6 > 999600/1000 = 999.6 > 999650/1000 = 999.6 // expected 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 = -999.6 // expected -999.7 > -999600/1000 = -999.6 > -999550/1000 = -999.5 // expected -999.6 > -999500/1000 = -999.5 > -999450/1000 = -999.5 > -999400/1000 = -999.4 > -999350/1000 = -999.4 > -999300/1000 = -999.3 > -999250/1000 = -999.2 // expected -999.3 > -999200/1000 = -999.2 > -999150/1000 = -999.1 // expected -999.2 > -999100/1000 = -999.1 > -999050/1000 = -999.0 // expected -999.1 > > > Is this actual rounding the result of a rule or is it pseudo random ? > -- 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/138f55d2-e7a6-4f12-85fd-d14bc42699f7%40googlegroups.com.
