Reference · Math

math.isfinite

math.isfinite(num) -> bool

What it does

Whether a number is neither infinite nor NaN, as Python's math.isfinite. Every int is finite; a float is finite unless arithmetic ran past the largest float or had no answer. It is the test to run before storing a computed float or sending it as JSON.

Examples

print(math.isfinite(1), math.isfinite(2.5), math.isfinite(1e308))print(math.isfinite(float("inf")), math.isfinite(float("nan")))

true true truefalse false

Edge cases

• The largest int is finite; so are 0.0 and -0.0.
• A float that overflowed is infinite and so not finite: 1e308 * 10 is inf.
• inf - inf is NaN, and not finite either.

print(math.isfinite(9223372036854775807), math.isfinite(-0.0))print(math.isfinite(1e308 * 10), math.isfinite(float("inf") - float("inf")))

true truefalse false

Errors

An argument that is not a number is a runtime error, not an error value: text, null and a decimal are refused rather than reported as not finite.

print(math.isfinite("1"))

line 1: `math.isfinite` expects a number as argument 1, got str

Chaining

In a pipeline the number comes first. Dropping the values that cannot be charted:

print(1e308 * 10 | math.isfinite)print([1.5, float("inf"), 2.5, float("nan")] | filter(math.isfinite))

false[1.5, 2.5]

See also

math.isinf, math.isnan, math.isclose, float

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