Question about floating point
Frank Millman
frank at chagford.com
Sat Sep 1 07:27:59 EDT 2018
"Frank Millman" wrote in message news:...
"Frank Millman" wrote in message news:pm3l2m$kv4$1 at blaine.gmane.org...
>
> I know about this gotcha -
>
> >>> x = 1.1 + 2.2
> >>> x
> 3.3000000000000003
>
[...]
I have enjoyed the discussion, and I have learnt a lot about floating point.
Thanks to all.
I have just noticed one oddity which I thought worth a mention.
>>> from decimal import Decimal as D
>>> f"{D('1.1')+D('2.2'):.60f}"
'3.300000000000000000000000000000000000000000000000000000000000'
>>> '{:.60f}'.format(D('1.1') + D('2.2'))
'3.300000000000000000000000000000000000000000000000000000000000'
>>> '%.60f' % (D('1.1') + D('2.2'))
'3.299999999999999822364316059974953532218933105468750000000000'
>>>
The first two format methods behave as expected. The old-style '%' operator
does not.
Frank
More information about the Python-list
mailing list