Ruby：sum 与 inject(:+) 产生不同的结果
Ruby: sum vs. inject(:+) produces different results
我注意到 array.sum 和 array.inject(:+) 产生了不同的结果。这是什么原因？
a = [10, 1.1, 6.16]
a.inject(:+)
# => 17.259999999999998
a.sum
# => 17.26
当某些输入是浮点数时，Array#sum 的 C 实现委托给 Kahan summation algorithm。
这个算法...
...significantly reduces the numerical error in the total obtained by adding a sequence of finite precision floating point numbers, compared to the obvious approach. This is done by keeping a separate running compensation (a variable to accumulate small errors).
-- Wikipedia
见Array#sum and the implementation on Github。
我注意到 array.sum 和 array.inject(:+) 产生了不同的结果。这是什么原因？
a = [10, 1.1, 6.16]
a.inject(:+)
# => 17.259999999999998
a.sum
# => 17.26
当某些输入是浮点数时，Array#sum 的 C 实现委托给 Kahan summation algorithm。
这个算法...
...significantly reduces the numerical error in the total obtained by adding a sequence of finite precision floating point numbers, compared to the obvious approach. This is done by keeping a separate running compensation (a variable to accumulate small errors).
-- Wikipedia
见Array#sum and the implementation on Github。