On 01/-10/-28163 02:59 PM, Alan Gauld wrote:
"Steven D'Aprano" <[email protected]> wrote
<snip>
The right way is to do it like this:
>>> x = 0.0
>>> for i in range(1, 11):
... x = i*0.1
...
>>> x == 1.0
True
But this I don't understand.
Why would you use a loop when the final value is just
the final multiplication. Since you know the final value
in advance (you need it to create the loop!) why not
just do the final multiplication directly:
x = 10*0.1
I think I'm missing something?
What you missed was the original context, where other work was being
done in the loop, and where the accuracy of the "accumulator" was being
misunderstood. Steven's point was that doing repeated sums of a
quantized value is going to lead to a cumulative error, which can be
minimized by using integers and scaling.
DaveA
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