Python 3.2+mathterm

math.isfinite

checking

Returns True if the number is finite — neither inf nor nan. Handy for checking the result of a calculation.

Syntax

math.isfinite(x)

One call covers both anomalies at once: isfinite is false for inf and for nan alike, whereas isinf(nan) is False, so an infinity-only check quietly lets nan through. That matters at the data boundary: float() happily parses the strings 'inf' and 'nan' from input, and overflow in float arithmetic (1e308 * 10) silently yields inf instead of raising.

Examples

import math
print(math.isfinite(42.0))    # → True
print(math.isfinite(math.inf))  # → False
print(math.isfinite(math.nan))  # → False
print(math.isfinite(1e308))   # → True
print(math.isfinite(float('inf')))  # → False
print(math.isfinite(-0.0))  # → True

See also

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