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 > <golang-nuts@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 > <javascript:>> 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 <javascript:>. > 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 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/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. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/44D16F57-2D09-455C-9A24-7F53BB4E8C7A%40ix.netcom.com.
