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yap-6.3/library/mpi/examples/demo1.pl

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%% demo1.pl -- Stasinos Konstantopoulos
%% konstant@let.rug.nl, Thu Jan 24 2002
%%
%%
%% This the calculation that needs to be performed, in this case
%% the sum of [From..To]
%%
calc( From, From, Acc, Res ) :- !,
Res is Acc + From.
calc( From, To, Acc, Res ) :- !,
Acc1 is Acc + To,
To1 is To - 1,
calc( From, To1, Acc1, Res ).
%%
%% This spreads the work among the processors
%% and collects the results.
%%
do(0, Num):-
integer(Num), !,
Half is Num // 2,
format( 'Proc 0: Calculating ~q..~q~n', [1, Half] ),
calc( 1, Half, 0, R1 ),
format( 'Proc 0: Done! (~q)~n', [R1] ),
mpi_receive( R2, Source, Tag ), % Receive any Source, any Tag
format( 'Proc ~q said: ~q (Tag: ~q)~n', [Source,R2,Tag] ),
% mpi_receive( R2, 1, 1 ), % Be more particular
Res is R1 + R2,
format( 'Sum(1..~q) = ~q~n', [Num,Res] ).
do(1, Num):-
integer(Num), !,
Half is Num // 2,
format( 'Proc 1: Calculating ~q..~q~n', [Half,Num] ),
calc( Half, Num, 0, Res ),
format( 'Proc 1: Done! (~q)~n', [Res] ),
mpi_send( Res, 0, 1 ).
do(0, _):-
!,
mpi_receive(T, Source, Tag),
format( '0: Proc ~q said: ~q (Tag: ~q)~n', [Source,T,Tag] ).
do(1, Term):-
!,
mpi_send(Term, 0, 1),
format( "1: I sent ~q (Tag: 1) to 0~n", [Term] ).
%%
%% This is the entry point
%%
start(Job) :-
mpi_open( Rank, NumProc, ProcName ),
format( 'Rank: ~q NumProc: ~q, ProcName: ~q~n', [Rank,NumProc,ProcName] ),
do( Rank, Job ),
format( 'Rank ~q finished!~n', [Rank] ).