| |
⍳10
0 1 2 3 4 5 6 7 8 9
+/ ⍳10
45
| +/ ⍳n | |
| 2 ÷⍨ (+/⍳n) + (+/⍳n) |
x ←→ (x+x)÷2 ←→ 2÷⍨x+x |
| 2 ÷⍨ +/ (⍳n) + (⍳n) |
+
is associative and commutative |
| 2 ÷⍨ +/ (⍳n) + ⌽⍳n |
+
is associative and commutative |
| 2 ÷⍨ +/ n ⍴ n-1 |
lemma (property of ⍳
and +
and ⌽) |
| 2 ÷⍨ n × n-1 |
repeated addition is multiplication |
| 2 ! n |
definition of ! |
|