Databases
StackOverflow2013
Postsdbo
POConcurrent Prime Generator
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POConcurrent Prime Generator
    primarykey
    data
    text
    <p>I'm going through the problems on projecteuler.net to learn how to program in Erlang, and I am having the hardest time creating a prime generator that can create all of the primes below 2 million, in less than a minute. Using the sequential style, I have already written three types of generators, including the Sieve of Eratosthenes, and none of them perform well enough.</p> <p>I figured a concurrent Sieve would work great, but I'm getting bad_arity messages, and I'm not sure why. Any suggestions on why I have the problem, or how to code it properly? </p> <p>Here's my code, the commented out sections are where I tried to make things concurrent:</p> <pre> -module(primeserver). -compile(export_all). start() -> register(primes, spawn(fun() -> loop() end)). is_prime(N) -> rpc({is_prime,N}). rpc(Request) -> primes ! {self(), Request}, receive {primes, Response} -> Response end. loop() -> receive {From, {is_prime, N}} -> if N From ! {primes, false}; N =:= 2 -> From ! {primes, true}; N rem 2 =:= 0 -> From ! {primes, false}; true -> Values = is_not_prime(N), Val = not(lists:member(true, Values)), From ! {primes, Val} end, loop() end. for(N,N,_,F) -> [F(N)]; for(I,N,S,F) when I + S [F(I)|for(I+S, N, S, F)]; for(I,N,S,F) when I + S =:= N -> [F(I)|for(I+S, N, S, F)]; for(I,N,S,F) when I + S > N -> [F(I)]. get_list(I, Limit) -> if I [I*A || A [] end. is_not_prime(N) -> for(3, N, 2, fun(I) -> List = get_list(I,trunc(N/I)), lists:member(N,lists:flatten(List)) end ). %%L = for(1,N, fun() -> spawn(fun(I) -> wait(I,N) end) end), %%SeedList = [A || A %% lists:foreach(fun(X) -> %% Pid ! {in_list, X} %% end, SeedList) %% end, L). %%wait(I,N) -> %% List = [I*A || A lists:member(X,List) %% end. </pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USiCodez
    1. USDan
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POConcurrent Prime Generator
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POConcurrent Prime Generator
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POConcurrent Prime Generator
      1. This table or related slice is empty.
      1. VTUpMod
    1. COHow did you suppress Markdown's inappropriate syntax coloring?
      singulars
      1. POConcurrent Prime Generator
      1. USHugh Allen
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload