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Re: int() function

by haj (Curate)
on Oct 24, 2020 at 11:09 UTC ( #11123117=note: print w/replies, xml ) Need Help??

in reply to int() function

Edit: I realise now that this is not a good answer to your question, so scratch that. I need to go now, so can't fix it in the next minutes - sorry for the noise.

The issue is, as ever so often, limited accuracy of floating point calculations. The number 1.15 can not be represented exactly as a floating point number, so the representation is either a tiny bit below, or a tiny bit above 1.15.

Apparently it is a tiny bit below 1.15, so the result of the multiplication is a tiny bit below 195.5, and after the addition of 0.5 you get something a tiny bit below 196.

The int function doesn't care about how tiny that bit might be, it happily throws away everything below 196 because, well, it is less than 196.

There's nothing magical about the number 170: The tiny error is either negative or positive, and whenever it is negative, int will behave like that.

So, using printf is a well accepted way to get around this issue, because it gets the rounding right for normal expectations.

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