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Explore Stack InternalLook 'ma, no built-in totient!
4 bytes saved thanks to @H.PWiz
0{⍵=1:⍺⋄(⍺+1)∇+0⋄1+∇+/1=⍵∨⍳⍵}¨1+⍳99 How?
Apparently I went for the longer (and harder) totient formula first. See revisions history.
⍳⍵ - 1 to n
⍵∨ - gcd with n
1= - equal to 1?
+/ - sum 'em all
This is the totient. All the rest is wrapper for the counting (1+∇) and applying on the range 2..100 (¨1+⍳99).
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇+/1=⍵∨⍳⍵}¨1+⍳99 How?
Apparently I went for the longer (and harder) totient formula first. See revisions history.
⍳⍵ - 1 to n
⍵∨ - gcd with n
1= - equal to 1?
+/ - sum 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.
Look 'ma, no built-in totient!
4 bytes saved thanks to @H.PWiz
{⍵=1:0⋄1+∇+/1=⍵∨⍳⍵}¨1+⍳99 How?
Apparently I went for the longer (and harder) totient formula first. See revisions history.
⍳⍵ - 1 to n
⍵∨ - gcd with n
1= - equal to 1?
+/ - sum 'em all
This is the totient. All the rest is wrapper for the counting (1+∇) and applying on the range 2..100 (¨1+⍳99).
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇×/⍵,1-÷o∇+/⍨0=⍵|⍨o←(⊢~∘.×⍨)1+⍳⍵1=⍵∨⍳⍵}¨1+⍳99 How?
Apparently I went for the longer (and harder) totient formula first. See revisions history.
(⊢~∘.×⍨)1+⍳⍵⍳⍵ - primes (better don't ask)
o/⍨1 to - filter byn
0=⍵|⍨o⍵∨ - divisibility bygcd with n
1-÷o1= - array wise 1- recipeocalequal to 1?
×+/⍵, - prepend n, and multiplysum 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇×/⍵,1-÷o/⍨0=⍵|⍨o←(⊢~∘.×⍨)1+⍳⍵}¨1+⍳99 How?
(⊢~∘.×⍨)1+⍳⍵ - primes (better don't ask)
o/⍨ - filter by
0=⍵|⍨o - divisibility by n
1-÷o - array wise 1- recipeocal
×/⍵, - prepend n, and multiply 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇+/1=⍵∨⍳⍵}¨1+⍳99 How?
Apparently I went for the longer (and harder) totient formula first. See revisions history.
⍳⍵ - 1 to n
⍵∨ - gcd with n
1= - equal to 1?
+/ - sum 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇×/⍵,1-÷o/⍨0=⍵|⍨o←(⊢~∘.×⍨)1+⍳⍵}¨1+⍳99 How?
(⊢~∘.×⍨)1+⍳⍵ - primes (better don't ask)
o/⍨ - filter by
0=⍵|⍨o - divisibility by n
1-÷o - array wise 1- recipeocal
×/⍵, - prepend n, and multiply 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.
Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇×/⍵,1-÷o/⍨0=⍵|⍨o←(⊢~∘.×⍨)1+⍳⍵}¨1+⍳99 Look 'ma, no built-in totient!
0{⍵=1:⍺⋄(⍺+1)∇×/⍵,1-÷o/⍨0=⍵|⍨o←(⊢~∘.×⍨)1+⍳⍵}¨1+⍳99 How?
(⊢~∘.×⍨)1+⍳⍵ - primes (better don't ask)
o/⍨ - filter by
0=⍵|⍨o - divisibility by n
1-÷o - array wise 1- recipeocal
×/⍵, - prepend n, and multiply 'em all
This is the totient. All the rest is wrapper for the counting and applying on 2..100.