variance - nodef/extra-math GitHub Wiki
Find the mean of squared deviation of numbers from its mean.
function variance(...xs)
// xs: a list of numbers
const xmath = require('extra-math');
xmath.variance(1, 2);
// → 0.25
xmath.variance(1, 2, 3);
// → 0.6666666666666666
xmath.variance(1, 2, 3, 4);
// → 1.25