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authorEli Sadoff <9064062+snood1205@users.noreply.github.com>2019-12-11 02:25:54 (GMT)
committerKenta Murata <mrkn@users.noreply.github.com>2019-12-11 02:25:54 (GMT)
commit7e9b1609dae0998a4418179f40dc488842c56e5d (patch)
treee9c1953a47fa6b47fd2d3f380469ae3f68d3dcd2 /enum.c
parent86e2c013d7ade7c93077d599e155aae0f3b632e8 (diff)
Added documentation for integer range sums (#1593)
Diffstat (limited to 'enum.c')
-rw-r--r--enum.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/enum.c b/enum.c
index 89148e9..db5f4d3 100644
--- a/enum.c
+++ b/enum.c
@@ -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.
*/