Actually this isn’t quite so simple - as the problem outline below compounds itself by the use of #average (which uses #sum and not #sumNumbers) and thus gives a less precise answer.
Why wouldn’t #average use #sumNumbers inside? Or does there need to be #averageNumbers as a complement …. Argggg it makes my head hurt. Its important as we compare differently to python and this then makes us waste time. Tim > On 20 Mar 2020, at 15:19, Tim Mackinnon <tim@testit.works> wrote: > > Actually I can answer my own question - its the difference between #sum and > #sumNumbers (and an easy mistake to make - I almost wish that sum was the > sumNumbers implementation and there was a sumSample that behaved like now) > >> On 20 Mar 2020, at 14:52, Tim Mackinnon <tim@testit.works >> <mailto:tim@testit.works>> wrote: >> >> Hi guys - I recall this came up a few months ago, but I’m curious about the >> difference of Pharo’s use of Float64 vs Python - as I assumed that if >> languages use the same IEEE spec (or whatever spec it is) that simple stuff >> would be quite similar. >> >> I am curious why in Python adding these numbers: >> >> y = 987.9504418944 + 815.2627636718801 + 1099.3898999037601 + >> 1021.6996069333198 + 1019.8750146478401 + 1084.5603759764 + >> 1008.2985131833999 + 1194.9564575200002 + 893.9680444336799 + >> 1032.85460449136 + 905.9324633786798 + 1024.2805590819598 + >> 784.5488305664002 + 957.3522631840398 + 1001.7526196294 >> print(y) >> print(y / 15) >> >> Gives: >> >> 14832.682458496522 >> 988.8454972331015 >> >> In pharo I have noticed an anomaly which I thought was precision but it may >> be something odd with iterators. >> >> y := 987.9504418944 + 815.2627636718801 + 1099.3898999037601 + >> 1021.6996069333198 + 1019.8750146478401 + 1084.5603759764 + >> 1008.2985131833999 + 1194.9564575200002 + 893.9680444336799 + >> 1032.85460449136 + 905.9324633786798 + 1024.2805590819598 + >> 784.5488305664002 + 957.3522631840398 + 1001.7526196294. >> y. >> y / 15. >> >> Gives the same as Python. >> >> BUT: >> >> z := {987.9504418944 . 815.2627636718801 . 1099.3898999037601 . >> 1021.6996069333198 . 1019.8750146478401 . 1084.5603759764 . >> 1008.2985131833999 . 1194.9564575200002 . 893.9680444336799 . >> 1032.85460449136 . 905.9324633786798 . 1024.2805590819598 . >> 784.5488305664002 . 957.3522631840398 . 1001.7526196294} sum. >> z. >> z / 15. >> >> Gives >> 14832.68245849652 >> 988.8454972331014 >> >> Is this correct? >> >> >
