Erlang-多核并发时的树形通信

这段代码不是我写的，谢谢实验室的的师妹，接下来要把树形通信应用到求Pi上去。

-module(my).
-export([main/1,temp/2,integer_to_atom/1,judge/3,ceil/1]).

main(CoreNum) -> SumDie=temp(CoreNum,1),
                 Time=erlang:now(),
                 createP(1,CoreNum,SumDie,Time),
                 io:format("").

temp(Num,SNum) when Num =< SNum -> SNum;
temp(Num,SNum) -> temp(Num,SNum*2).

createP(N,CoreNum,SumDie,Time) when N =:= CoreNum ->
               register(integer_to_atom(N),spawn(fun() -> loopin(N,2,SumDie,CoreNum,20000,Time) end));
createP(N,CoreNum,SumDie,Time) ->
               register(integer_to_atom(N),spawn(fun() -> loopin(N,2,SumDie,CoreNum,5000000,Time) end)),
               createP(N+1,CoreNum,SumDie,Time).

integer_to_atom(Int) -> T=integer_to_binary(Int),
                        binary_to_atom(T,utf8).

loopin(Number,Die,SumDie,CoreNum,NN,Time) -> T1=erlang:now(),
                                             xunhuan(NN),
                                             T2=erlang:now(),
                                             io:format("the ~p core cycle time : ~pms~n",[Number,timer:now_diff(T2,T1)/1000]),
                                             loop(Number,Die,SumDie,CoreNum,Time).

xunhuan(0) ->ok;
xunhuan(NN)->xunhuan(NN-1).
%每个core 收发信息
loop(Number,Die,SumDie,CoreNum,Time) ->
    if
        Die =:= SumDie*2 -> io:format("~p need time : ~pms~n",[Number,timer:now_diff(erlang:now(),Time)/1000]);
                           %io:format("over");

      true -> [H|L]=judge(CoreNum,Number,Die),
            if
                H =:= 1 -> [H2|_]=L,
                        {send,To,DieThat}=H2,
                       (integer_to_atom(To))!{Number,DieThat},
                       io:format("~p need time : ~pms~n",[Number,timer:now_diff(erlang:now(),Time)/1000]);
                true -> [H2|_]=L,
                    {get,From,DieThat}=H2,
                    receive
                        {From,DieThat} -> io:format("~p get info from ~p~n",[Number,From]),
                                    loop(Number,Die*2,SumDie,CoreNum,Time)
                    end
            end
     end.

%判断每核的收发
judge(SumCore,Number,Die) -> R=lslast(SumCore,Number,Die),
   if
      R =:= 1 ->
         if
            Number rem Die =:= 1 -> {DieThat,To}=find(Number,Die),
                                    [1,{send,To,DieThat}];
            true -> [1,{send,Number-erlang:trunc(Die/2),Die}]
         end;

      true ->
         if
            Number rem Die =:= 1 -> [0,{get,Number+erlang:trunc(Die/2),Die}];
            true -> [1,{send,Number-erlang:trunc(Die/2),Die}]
         end
   end.

%判断最后一核信息发送给哪里
find(Number,Die) -> Current_order=ceil(Number*2/Die),
   if
      Current_order rem 2 =:= 0 -> {Die,Number-erlang:trunc(Die/2)};
      true -> find(Number,Die*2)
   end.

%计算live的核在本轮迭代中的序号,若为最后一个标记为1.
lslast(SumCores,Number,Die) -> Current_order=ceil(Number*2/Die),
                               Sum_order=ceil(SumCores*2/Die),
                               %io:format("~p ~p ~p ~p ~p~n",[SumCores,Number,Die,Current_order,Sum_order]),
      if
         Current_order =:= Sum_order -> 1;
         true -> 0
      end.

%对小数取上界,比如ceil(15.1)=16
ceil(N) -> T=trunc(N),
           Temp = N-T,
   case Temp =:= 0.000 of
      true -> T;
      false -> T+1
   end.