How do I type a floating point infinity literal in python

Question:

How do I type a floating point infinity literal in python?

I have heard 

 inf = float('inf')

is non portable. Thus, I have had the following recommended:

 inf = 1e400

Is either of these standard, or portable? What is best practice?

Asked By: fmark

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Source

Answers:

In python 2.6 it is portable if the CPU supports it

The float() function will now turn the
string nan into an IEEE 754 Not A
Number value, and +inf and -inf into
positive or negative infinity. This
works on any platform with IEEE 754
semantics.

Answered By: mmmmmm

float('inf') is non portable as in not portable back to Python 2.5 when the string output varies between platforms. From 2.6 and onwards float('inf') is guaranteed to work on IEEE-754-compliance platforms (ref: http://www.python.org/dev/peps/pep-0754/).

(And the recommendation seems to be in the range 1e30000, not just 1e400.)

Answered By: kennytm

Perhaps you could do something like this

try:
    inf = float('inf')
except:  # check for a particular exception here?
    inf = 1e30000
Answered By: John La Rooy

Starting from Python 3.6, you can use math.inf.

import math
math.inf
Answered By: barjak