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Floating point minimum and maximum exponent values in Python

+1 vote
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Why the maximum and minimum exp values are 1024 and -1021?:

 >>> sys.float_info
sys.float_info(max=1.7976931348623157e+308, max_exp=1024, 
max_10_exp=308, min=2.2250738585072014e-308, min_exp=-1021, 
min_10_exp=-307, dig=15, mant_dig=53, epsilon=2.220446049250313e-16, 
radix=2, rounds=1)

The values (in double precision) 0 and 2047 are reserved for zero, infinity and NaN (in combination with the fraction), so I was expecting -1022 and 1023...

posted Jul 16, 2013 by anonymous

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1 Answer

0 votes
help(sys.floatinfo)
... lots of other info ...
| maxexp
| DBLMAXEXP -- maximum int e such that radix(e-1) is representable
|
| minexp
| DBLMIN_EXP -- minimum int e such that radix(e-1) is a normalized float
answer Jul 17, 2013 by Salil Agrawal
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