Reference · Vectors

vec.log

vec.log(list) -> list

What it does

The natural logarithm of each item, as a list of floats. For another base divide by the logarithm of that base: vec.div(vec.log(xs), math.log(2)) is log base 2.

Examples

print(vec.log([1, math.e, 100]))print(vec.log([8, 1024]) | vec.div(math.log(2)))

[0.0, 1.0, 4.605170185988092][3.0, 10.0]

Edge cases

• 0 gives -inf and a negative number gives NaN, not an error, unlike math.log(0).
• The empty list, or null, gives the empty list.

print(vec.log([0, -1]))print(vec.log([]), vec.log(null))

[-inf, NaN][] []

Errors

An item that is not an int or a float, or an argument that is not a list, is a runtime error, not an error value.

print(vec.log([1, "e"]))

line 1: `vec.log` expects a list of numbers, but item 1 is str

Chaining

Log returns of a price series: the differences of the logs.

let prices = [100, 110, 99]print(prices | vec.log | vec.diff | vec.round(4))

[0.0953, -0.1054]

See also

vec.exp, vec.sqrt, math.log, vec.diff

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