[Python-Dev] Mixing float and Decimal -- thread reboot

Adam Olsen rhamph at gmail.com
Fri Mar 26 00:10:56 CET 2010

On Thu, Mar 25, 2010 at 04:18, Steven D'Aprano <steve at pearwood.info> wrote:
> def myfunc(x, y):
>    if x == y:
>        return 1.0
>    else:
>        return something_complicated**(x-y)
> Optimising floating point code is fraught with dangers (the above fails
> for x=y=INF as well as NAN) but anything that make Not A Numbers
> pretend to be numbers is a bad thing.

What about this:

def myfunc(x):
    if x >= THRESHOLD:
        return 1.0
        return something_complicated(x)

If one behaves right it's more likely a fluke, not a designed in
feature.  It's certainly not obvious without covering every comparison
with comments.

Maybe that's the solution.  Signal by default on comparison, but add a
collection of naneq/naneg/etc functions (math module, methods,
whatever) that use a particular quiet mapping, making the whole thing

Adam Olsen, aka Rhamphoryncus

More information about the Python-Dev mailing list