[Python-Dev] math.areclose ...?
raymond.hettinger at verizon.net
Mon Feb 6 22:37:22 CET 2006
> Does it help to spell it like this?
> def areclose(x, y, relative_err = 1.e-5, absolute_err=1.e-8):
> diff = abs(x - y)
> ave = (abs(x) + abs(y))/2
> return diff < absolute_err or diff/ave < relative_err
There is a certain beauty and clarity to this presentation; however, it is
* the division by either absolute_err and relative_err can overflow or
trigger a ZeroDivisionError
* the 'or' part of the expression can introduce an unnecessary discontinuity
in the first derivative.
The original Numeric definition is likely to be better for people who know
what they're doing; however, I still question whether it is an appropriate
remedy for the beginner issue
of why 1.1 + 1.1 + 1.1 doesn't equal 3.3.
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