Reference · Vectors

vec.pow

vec.pow(list, num) -> list

What it does

Each item raised to a power. The result is always a list of floats, even for ints to a whole power: vec.pow([2, 3], 2) is [4.0, 9.0]. A fractional power takes a root, so vec.pow(xs, 0.5) is vec.sqrt(xs).

Examples

print(vec.pow([1, 2, 3], 2))print(vec.pow([4, 9], 0.5))print(vec.pow([2, 3], 3))

[1.0, 4.0, 9.0][2.0, 3.0][8.0, 27.0]

Edge cases

• A negative number to a fractional power is NaN, not an error.
• x to the power 0 is 1.0, for 0 too; a negative power gives the reciprocal.
• The empty list gives the empty list.
• A power past what a float holds is inf.

print(vec.pow([-8], 1 / 3), vec.pow([-2], 0.5))print(vec.pow([0, 5], 0), vec.pow([2, 4], -1))print(vec.pow([], 2))print(vec.pow([10], 400))

[NaN] [NaN][1.0, 1.0] [0.5, 0.25][][inf]

Errors

A list with an item that is not an int or a float, a missing or non-numeric power, or a first argument that is not a list are runtime errors, not error values.

print(vec.pow([1, "a"], 2))

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

print(vec.pow([1, 2]))

line 1: `vec.pow` expects a number as argument 2, got nothing

Chaining

xs | vec.pow(2) squares a list; summed, it is the squared length:

print(vec.arange(1, 4) | vec.pow(2) | sum)print([3, 4] | vec.pow(2) | sum | math.sqrt)

14.05.0

See also

vec.sqrt, vec.exp, vec.mul, vec.norm, math.pow

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