Reference · Math

sqrt

sqrt(num) -> float

What it does

The square root, always a float: sqrt(16) is 4.0. A negative number gives NaN, not an error; math.sqrt is the version that errors, as Python does.

Examples

print(sqrt(16), sqrt(2), sqrt(2.25))print(sqrt(pow(3, 2) + pow(4, 2)))

4.0 1.4142135623730951 1.55.0

Edge cases

• The result is a float even for a perfect square: sqrt(16) is 4.0, int makes it 4.
• sqrt(-1) is NaN, which equals nothing, itself included: test it with math.isnan.
• sqrt(0) is 0.0.

print(type_of(sqrt(16)), int(sqrt(16)))print(sqrt(-1), sqrt(-1) == sqrt(-1), math.isnan(sqrt(-1)))print(sqrt(0))

float 4NaN false true0.0

Errors

A string, null or a boolean is a runtime error, not an error value, and so is a decimal: convert it with float first.

print(sqrt("4"))

line 1: `sqrt` expects a number as argument 1, got str

print(sqrt(4m))

line 1: `sqrt` expects a number as argument 1, got dec (this works on floats: convert a dec with float(x))

Chaining

print(16 | sqrt, [1, 4, 9] | map(sqrt))print(2 | sqrt | round(3))

4.0 [1.0, 2.0, 3.0]1.414

See also

pow, math.sqrt, math.isnan, abs, round

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