tests/fail/demo_sieve.lua@f9bb0e212d28 (annotated)
tests/fail/demo_sieve.lua
Wed, 24 Nov 2010 02:52:37 +0000
- author
- Matthew Wild <mwild1@gmail.com>
- date
- Wed, 24 Nov 2010 02:52:37 +0000
- changeset 138
- f9bb0e212d28
- parent 57
- 3e148db7f933
- permissions
- -rw-r--r--
Replace error reporting code with calls to LVM.traceback()
| 57 | 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 |
