If the computation doesn’t change observable value - then it’s the same value… (when use as a key/equality) - which is why a better detection of change might be on the “value added” - but if that isn’t stored, you’ll be back to same spot.
> On Feb 22, 2020, at 3:06 PM, 'simon place' via golang-nuts > <golang-nuts@googlegroups.com> wrote: > > are you sure? > > surely floats can have, say, a small number added, that depending of the > value, sometimes doesn't change them and sometimes does. seems to me the same > issue. > > On Saturday, 22 February 2020 19:58:09 UTC, robert engels wrote: > float equality is useful for determining if “something changed” (e.g. the > record has changed), you can also use float keys - the equality matters, the > actual value not so much. > >> On Feb 22, 2020, at 1:50 PM, 'simon place' via golang-nuts >> <golan...@googlegroups.com <>> wrote: >> >> absolutely, though even an epsilon is a bit of a hack IMHO. given the more >> ops you do the greater the potential discrepancy, and, i guess, you get a >> normal dist. of values, so any epsilon only has a probability of working, >> albeit potentially astronomically high probability. >> >> so then why even have float equality in the/any language at all? >> >> or might be nice if vet warned >> >> On Sunday, 26 January 2020 03:34:11 UTC, Kurtis Rader wrote: >> This is why you should never, ever, do a simple equality test involving a >> F.P. value derived from a calculation. You always have to apply an epsilon >> to define a range within which the two F.P. values should be considered >> equal. >> On Sat, Jan 25, 2020 at 7:14 PM Jason E. Aten <j.e...@gmail.com <>> wrote: >> >> https://play.golang.org/p/87bDubJxjHO <https://play.golang.org/p/87bDubJxjHO> >> >> I'd like to truncate a float64 to just 2 decimal places (in base 10), but >> math.Trunc is not helping me here... ideally I put 0.29 in and I get 0.29 >> out. >> Suggestions? Playground examples appreciated. >> >> package main >> >> import ( >> "fmt" >> "math" >> ) >> >> // truncate off everything after the last two decimals, no rounding. >> func decimal2(x float64) float64 { >> return math.Trunc(x*100) / 100 >> } >> >> func main() { >> x := 0.29 >> y := decimal2(x) >> fmt.Printf("x=%v -> y = %v", x, y) // prints x=0.29 -> y=0.28 >> } >> >> -- >> 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 golan...@googlegroups.com <>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/96528d64-a670-45ba-ad4c-0701dcd0d78d%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/96528d64-a670-45ba-ad4c-0701dcd0d78d%40googlegroups.com?utm_medium=email&utm_source=footer>. >> >> >> -- >> Kurtis Rader >> Caretaker of the exceptional canines Junior and Hank >> >> -- >> 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 golan...@googlegroups.com <>. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/golang-nuts/229c73ce-88fb-46a0-a2ee-8454cbaa6ae5%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/229c73ce-88fb-46a0-a2ee-8454cbaa6ae5%40googlegroups.com?utm_medium=email&utm_source=footer>. > > > -- > 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 > <mailto:golang-nuts+unsubscr...@googlegroups.com>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/c37a2676-e6d2-4513-bb82-aad9b4755d80%40googlegroups.com > > <https://groups.google.com/d/msgid/golang-nuts/c37a2676-e6d2-4513-bb82-aad9b4755d80%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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/283E5055-8AAB-4229-B0AE-73049BBA4D16%40ix.netcom.com.
