Reference · Math

math.log10

math.log10(num) -> float

What it does

The logarithm of a number to base 10, as a float, as Python's math.log10. It is exact for a power of ten, where math.log(x, 10) can miss by a digit. The number must be above zero.

Examples

print(math.log10(1000), math.log10(0.001), math.log10(2))print(math.log10(1e300), math.log10(12345))

3.0 -3.0 0.3010299956639812300.0 4.091491094267951

Edge cases

• A power of ten gives a whole float: math.log10(1000) is 3.0.
• A number between 0 and 1 gives a negative answer; the smallest positive float is fine.
• inf gives inf, NaN gives NaN.
• The number of digits in a positive int is math.floor(math.log10(n)) + 1.

print(math.log10(1000), math.log(1000, 10))print(math.log10(0.5), math.log10(5e-324))print(math.log10(math.inf), math.log10(math.nan))print(math.floor(math.log10(12345)) + 1, math.floor(math.log10(99)) + 1)

3.0 2.9999999999999996-0.3010299956639812 -323.3062153431158inf NaN5 2

Errors

Zero or a negative number is a runtime error (a domain error), not an error value: it stops the request, and ?? does not catch it. A value that is not a number is a runtime error too; a decimal is converted first with float.

print(math.log10(-5))

line 1: `math.log10`: math domain error (-5)

print(math.log10(dec("100")))

line 1: `math.log10` expects a number as argument 1, got dec (this works on floats: convert a dec with float(x))

Chaining

print(1000000 | math.log10)print([1, 10, 100] | map(math.log10))print(3 | math.pow(10) | math.log10)

6.0[0.0, 1.0, 2.0]4.771212547196624

See also

math.log, math.log2, math.log1p, math.pow

Edit this page on GitHub · every example's output was made by running it (tools/refcheck.mjs) · questions on Discord or r/quillo