"Frank Millman" wrote in message news:pm3l2m$kv4$1...@blaine.gmane.org...
I know about this gotcha -
>>> x = 1.1 + 2.2
>>> x
3.3000000000000003
[...]
>>> y = 3.3
>>> y
3.3
[...]
>>> z = (1.1 + 2.2) * 10 / 10
>>> z
3.3
Thanks to Chris and Stephen for the replies.
They were interesting, but actually did not answer the question that I
forgot to ask!
The reason for my query is this. I am assisting someone with an application
involving monetary values. I have been trying to explain why they should use
the decimal module. They have had a counter-argument from someone else who
says they should just use the rounding technique in my third example above.
My gut-feel says that they are wrong, but I don't have the knowledge to
prove it. I think a lot depends on what they are going to do with this value
down the line - maybe it is 'safe enough' for their purposes, so I don't
want to overstate my case. Are there edge cases where that rounding method
could fail?
Frank
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