Probably not the right forum for this? Or, at least, this doesn't work for me, in J.
Maybe chat would work. -- Raul On Thu, Oct 6, 2016 at 4:33 AM, Erling Hellenäs <[email protected]> wrote: > Hi all ! > > This test with an immutable list class shows how you can get a copy with one > changed element in 12 microseconds while the same copy with one changed > element with a non-immutable array takes 15 milliseconds. > > The tests are repeated, but it's the second test that counts. > > let mutable a = ImmList<int>.Empty > let mutable b = null; > let mutable c = null; > a <- a.AddFirstRange([1 .. 10000000]) > let stopWatch = System.Diagnostics.Stopwatch.StartNew() > b <- a.Update(5000000,-1); > stopWatch.Stop() > printfn "%f" stopWatch.Elapsed.TotalMilliseconds > //6.442300 > printfn "%A %A" (a.TryGet(5000000)) (b.TryGet(5000000)); > //5000001 -1 > let stopWatch = System.Diagnostics.Stopwatch.StartNew() > c <- a.Update(5000000,-1); > stopWatch.Stop() > printfn "%f" stopWatch.Elapsed.TotalMilliseconds > //0.011900 > let a = [|1 .. 10000000|] > let stopWatch = System.Diagnostics.Stopwatch.StartNew() > let b = Array.copy a; > b.[5000000] <- -1 > stopWatch.Stop() > printfn "%f" stopWatch.Elapsed.TotalMilliseconds > //15.108700 > printfn "%i %i" a.[5000000] b.[5000000]; > //5000001 -1 > let stopWatch = System.Diagnostics.Stopwatch.StartNew() > let c = Array.copy a; > c.[5000000] <- -1 > stopWatch.Stop() > printfn "%f" stopWatch.Elapsed.TotalMilliseconds > //14.760200 > > Cheers, > > Erling Hellenäs > > > > On 2016-10-05 02:34, Xiao-Yong Jin wrote: >>> >>> On Oct 4, 2016, at 2:01 PM, Louis de Forcrand <[email protected]> wrote: >>> >>> Maybe add a third setting to 9!:53 which copies a at the start of a tacit >>> verb involving in place operations? >> >> This is a good compromise between speed and sensible intuition. >> I guess a memcpy only when in-place-operation is detected wouldn't be >> slower in general than previous non-in-place operations. >> This could certainly be the default option. >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
