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contexts:
- name: "master"
prelude: |-
require 'bundler/setup'
require 'enumerable/statistics'
prelude: |-
n = 1000
ary = Array.new(n) { rand }
benchmark:
inject: |-
mean = ary.mean
var = ary.inject(0.0) { |sum, x|
sum += (x - mean) ** 2
} / (n - 1).to_f
while: |-
mean = ary.mean
i, var = 0, 0
while i < n
var += (ary[i] - mean) ** 2
i += 1
end
var /= n.to_f
pure_ruby: |-
i, m, m2, f, c = 0, 0.0, 0.0, 0.0, 0.0
while i < n
x = ary[i]
y = x - c
t = f + y
c = (t - f) - y
f = t
delta = x - m
m += delta / i
m2 += delta * (x - m)
i += 1
end
var = m2 / n
c_ext: var = ary.variance
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