Given a typical implementation of prime-finding, the following expression
works fine:
*(2 = +/[1] 0 = m ∘.| m) / m←⍳N*
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
However, trying to swap the sides of the selection gives an error message:
*m /⍨ 2 = +/[1] 0 = m ∘.| m←⍳N*
SYNTAX ERROR
m/⍨2=+/[1]0=m∘∘.∣m←⍳N
^ ^
Adding a parentheses around the right-hand side does not work:
* m /⍨ (2 = +/[1] 0 = m ∘.| m←⍳N)*
SYNTAX ERROR
m/⍨(2=+/[1]0=m∘∘.∣m←⍳N)
^ ^
However, placing parens around the m makes it work:
* (m) /⍨ (2 = +/[1] 0 = m ∘.| m←⍳N)*
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
Another way of getting rid of the error is to place parens around the
function:
* m (/⍨) (2 = +/[1] 0 = m ∘.| m←⍳N)*
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
This surely can't be right?
Regards,
Elias
