round() function strange behaviour

[Erik de Castro Lopo]

brobbins333 at shaw.ca wrote:
> 
> the round() function will sometimes return a predictable result, as
> in:
> 
> round(45.67891, 2)
> >>> 45.68
> 
> but sometimes it will return something like:
> 
> round(56.78923, 2)
> >>> 56.789999999999999
> 
> 2.1 and 2.2 both behave this way on two different (Windows) computers.
> What's going on here?

You are running into problems with the floating point representation
of numbers. You may want to look up how floating point numbers are
stored in computers. Search google.

What you will fins is that some numbers like 2, 0.25 etc can be 
represented exactly in floating point format while others like
2/3 cannot.

Thats just the way it is.

Erik
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