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-rw-r--r-- | enum.c | 4 |
1 files changed, 4 insertions, 0 deletions
@@ -4029,6 +4029,10 @@ int_range_sum(VALUE beg, VALUE end, int excl, VALUE init) * { 1 => 10, 2 => 20 }.sum([]) #=> [1, 10, 2, 20] * "a\nb\nc".each_line.lazy.map(&:chomp).sum("") #=> "abc" * + * If the method is applied to an Integer range without a block, + * the sum is not done by iteration, but instead using Gauss's summation + * formula. + * * Enumerable#sum method may not respect method redefinition of "+" * methods such as Integer#+, or "each" methods such as Range#each. */ |