comparison: tests/fail/demo_sieve.lua
tests/fail/demo_sieve.lua
- changeset 57
- 3e148db7f933
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| 56:d02c7932cbf2 | 57:3e148db7f933 |
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| 1 -- sieve.lua | |
| 2 -- the sieve of Eratosthenes programmed with coroutines | |
| 3 -- typical usage: lua -e N=1000 sieve.lua | column | |
| 4 | |
| 5 -- generate all the numbers from 2 to n | |
| 6 function gen (n) | |
| 7 return coroutine.wrap(function () | |
| 8 for i=2,n do coroutine.yield(i) end | |
| 9 end) | |
| 10 end | |
| 11 | |
| 12 -- filter the numbers generated by `g', removing multiples of `p' | |
| 13 function filter (p, g) | |
| 14 return coroutine.wrap(function () | |
| 15 while 1 do | |
| 16 local n = g() | |
| 17 if n == nil then return end | |
| 18 if math.mod(n, p) ~= 0 then coroutine.yield(n) end | |
| 19 end | |
| 20 end) | |
| 21 end | |
| 22 | |
| 23 N=N or 1000 -- from command line | |
| 24 x = gen(N) -- generate primes up to N | |
| 25 while 1 do | |
| 26 local n = x() -- pick a number until done | |
| 27 if n == nil then break end | |
| 28 print(n) -- must be a prime number | |
| 29 x = filter(n, x) -- now remove its multiples | |
| 30 end | |
| 31 |
