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//
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// Estimation of Pi using Monte Carlo exploration process
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// gcc -std=c99 -O3 -o Pi Pi.c -lm
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// Emmanuel Quemener <emmanuel.quemener@ens-lyon.fr>
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// Cecill v2
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// Needed for gethostname
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#define _BSD_SOURCE
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#include <sys/unistd.h>
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <mpi.h>
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#include <stddef.h>
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#ifdef TIME
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#include <sys/time.h>
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#endif
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// Marsaglia RNG very simple implementation
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#define znew ((z=36969*(z&65535)+(z>>16))<<16)
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#define wnew ((w=18000*(w&65535)+(w>>16))&65535)
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#define MWC (znew+wnew)
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#define SHR3 (jsr=(jsr=(jsr=jsr^(jsr<<17))^(jsr>>13))^(jsr<<5))
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#define CONG (jcong=69069*jcong+1234567)
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#define KISS ((MWC^CONG)+SHR3)
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#define ITERATIONS 1000000000
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#define MWCfp MWC * 2.328306435454494e-10f
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#define KISSfp KISS * 2.328306435454494e-10f
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#define SHR3fp SHR3 * 2.328306435454494e-10f
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#define CONGfp CONG * 2.328306435454494e-10f
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#define PROCESS 1
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#ifdef LONG
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#define LENGTH long long
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#else
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#define LENGTH int
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#endif
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typedef struct compute_node {
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LENGTH iterations;
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int process;
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} node;
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unsigned int rotl(unsigned int value, int shift) {
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return (value << shift) | (value >> (sizeof(value) * CHAR_BIT - shift));
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}
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unsigned int rotr(unsigned int value, int shift) {
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return (value >> shift) | (value << (sizeof(value) * CHAR_BIT - shift));
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}
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LENGTH MainLoopGlobal(LENGTH iterations,unsigned int seed_w,unsigned int seed_z)
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{
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#if defined TCONG
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unsigned int jcong=seed_z;
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#elif defined TSHR3
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unsigned int jsr=seed_w;
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#elif defined TMWC
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unsigned int z=seed_z;
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unsigned int w=seed_w;
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#elif defined TKISS
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unsigned int jcong=seed_z;
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unsigned int jsr=seed_w;
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unsigned int z=seed_z;
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unsigned int w=seed_w;
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#endif
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LENGTH total=0;
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for (LENGTH i=0;i<iterations;i++) {
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#if defined TINT32
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#define THEONE 1073741824
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#if defined TCONG
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unsigned int x=CONG>>17 ;
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unsigned int y=CONG>>17 ;
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#elif defined TSHR3
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unsigned int x=SHR3>>17 ;
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unsigned int y=SHR3>>17 ;
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#elif defined TMWC
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unsigned int x=MWC>>17 ;
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unsigned int y=MWC>>17 ;
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#elif defined TKISS
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unsigned int x=KISS>>17 ;
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unsigned int y=KISS>>17 ;
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#endif
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#elif defined TINT64
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#define THEONE 4611686018427387904
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#if defined TCONG
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unsigned long x=(unsigned long)(CONG>>1) ;
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unsigned long y=(unsigned long)(CONG>>1) ;
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#elif defined TSHR3
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unsigned long x=(unsigned long)(SHR3>>1) ;
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unsigned long y=(unsigned long)(SHR3>>1) ;
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#elif defined TMWC
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unsigned long x=(unsigned long)(MWC>>1) ;
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unsigned long y=(unsigned long)(MWC>>1) ;
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#elif defined TKISS
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unsigned long x=(unsigned long)(KISS>>1) ;
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unsigned long y=(unsigned long)(KISS>>1) ;
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#endif
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#elif defined TFP32
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#define THEONE 1.0f
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#if defined TCONG
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float x=CONGfp ;
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float y=CONGfp ;
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#elif defined TSHR3
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float x=SHR3fp ;
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float y=SHR3fp ;
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#elif defined TMWC
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float x=MWCfp ;
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float y=MWCfp ;
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#elif defined TKISS
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float x=KISSfp ;
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float y=KISSfp ;
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#endif
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#elif defined TFP64
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#define THEONE 1.0f
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#if defined TCONG
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double x=(double)CONGfp ;
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double y=(double)CONGfp ;
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#elif defined TSHR3
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double x=(double)SHR3fp ;
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double y=(double)SHR3fp ;
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#elif defined TMWC
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double x=(double)MWCfp ;
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double y=(double)MWCfp ;
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#elif defined TKISS
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double x=(double)KISSfp ;
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double y=(double)KISSfp ;
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#endif
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#endif
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// Matching test
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unsigned long inside=((x*x+y*y) < THEONE) ? 1:0;
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total+=inside;
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}
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return(total);
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}
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int main(int argc, char *argv[]) {
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unsigned int seed_z=362436069,seed_w=52128862,process=PROCESS;
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// Number of NP or OpenMP processes <1024
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LENGTH iterations=ITERATIONS,insideMPI[1024],insideOpenMP[1024],
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part_inside,part_iterations,insides;
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int numtasks,rank,rc,tag=1,i;
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float pi;
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// Hostname supposed to be <128 characters
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char hostname[128];
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gethostname(hostname, sizeof hostname);
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#ifdef TIME
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struct timeval start,end;
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long int useconds;
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#endif
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MPI_Status Stat;
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MPI_Request RequestSend,RequestRecv,RequestSend2,RequestRecv2;
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rc = MPI_Init(&argc,&argv);
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if (rc != MPI_SUCCESS) {
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printf ("Error starting MPI program. Terminating.\n");
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MPI_Abort(MPI_COMM_WORLD, rc);
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}
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MPI_Comm_size(MPI_COMM_WORLD,&numtasks);
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const int nitems=2;
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int blocklengths[2] = {1,1};
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#ifdef LONG
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MPI_Datatype types[2] = {MPI_LONG, MPI_INT};
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#else
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MPI_Datatype types[2] = {MPI_INT, MPI_INT};
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#endif
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MPI_Datatype mpi_node_type;
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MPI_Aint offsets[2];
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offsets[0] = offsetof(node, iterations);
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offsets[1] = offsetof(node, process);
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MPI_Type_create_struct(nitems, blocklengths, offsets, types, &mpi_node_type);
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MPI_Type_commit(&mpi_node_type);
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MPI_Comm_rank(MPI_COMM_WORLD,&rank);
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if (rank==0) {
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if (argc > 1) {
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iterations=(LENGTH)atoll(argv[1]);
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process=atoi(argv[2]);
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}
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else {
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printf("\n\tPi : Estimate Pi with Monte Carlo exploration\n\n");
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printf("\t\t#1 : number of iterations (default 1 billion)\n\n");
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printf("\t\t#1 : number of OpenMP processes (default 1)\n\n");
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}
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printf ("\n\tInformation about architecture:\n\n");
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printf ("Sizeof int = %lld bytes.\n", (long long)sizeof(int));
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printf ("Sizeof long = %lld bytes.\n", (long long)sizeof(long));
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printf ("Sizeof long long = %lld bytes.\n", (long long)sizeof(long long));
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printf ("Max int = %u\n", INT_MAX);
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printf ("Max long = %ld\n", LONG_MAX);
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printf ("Max long long = %lld\n\n", LLONG_MAX);
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part_iterations=iterations/(numtasks*process)+1;
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node send;
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send.iterations=part_iterations;
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send.process=process;
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// Split part of code
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for (i=1;i<numtasks;i++) {
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rc = MPI_Isend(&send, 1, mpi_node_type, i, tag, MPI_COMM_WORLD, &RequestSend);
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}
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MPI_Wait(&RequestSend,&Stat);
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#ifdef TIME
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gettimeofday(&start,(struct timezone *)0);
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#endif
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#pragma omp parallel for
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for (int i=0 ; i<process; i++) {
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insideOpenMP[i]=MainLoopGlobal(part_iterations,
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rotr(seed_w,process),
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rotl(seed_z,process));
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printf("\t(%s,%i) found %lld for process %i\n",hostname,0,
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(long long)insideOpenMP[i],i);
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}
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printf("\n");
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insides=0;
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for (int i=0 ; i<process; i++) {
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insides+=insideOpenMP[i];
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}
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#ifdef TIME
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gettimeofday(&end,(struct timezone *)0);
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useconds=(end.tv_sec-start.tv_sec)*1000000+end.tv_usec-start.tv_usec;
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printf("\tOn %s with %i find %lld inside in %lu useconds.\n",
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hostname,rank,(long long)insides,useconds);
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#else
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printf("\tOn %s with %i find %lld inside\n",hostname,rank,
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(long long)insides);
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#endif
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// Join part of code
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for (i=1;i<numtasks;i++) {
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#ifdef LONG
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rc = MPI_Irecv(&insideMPI[i], 1, MPI_LONG_LONG, i, tag,
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MPI_COMM_WORLD, &RequestRecv2);
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#else
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rc = MPI_Irecv(&insideMPI[i], 1, MPI_INT, i, tag,
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MPI_COMM_WORLD, &RequestRecv2);
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#endif
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MPI_Wait(&RequestRecv2,&Stat);
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printf("\tReceive %lu inside from rank %i\n",(unsigned long)insideMPI[i],i);
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insides+=insideMPI[i];
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}
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pi=4.*(float)insides/(float)((iterations/numtasks)*numtasks);
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printf("\n\tPi=%.40f\n\twith error %.40f\n\twith %lld iterations\n\n",pi,
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fabs(pi-4*atan(1.))/pi,(long long)iterations);
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}
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else
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{
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// Receive information from master
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node recv;
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rc = MPI_Irecv(&recv, 1, mpi_node_type, 0, tag, MPI_COMM_WORLD, &RequestRecv);
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MPI_Wait(&RequestRecv,&Stat);
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printf("\t(%s,%i) receive from master %lld with %i process\n",
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hostname,rank,(long long)recv.iterations,recv.process);
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#ifdef TIME
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gettimeofday(&start,(struct timezone *)0);
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#endif
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#pragma omp parallel for
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for (int i=0 ; i<recv.process; i++) {
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insideOpenMP[i]=MainLoopGlobal(recv.iterations,rotr(seed_w,rank+process),rotl(seed_z,rank+process));
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printf("\t(%s,%i) found %lld for process %i\n",hostname,rank,
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(long long)insideOpenMP[i],i);
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}
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printf("\n");
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part_inside=0;
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for (int i=0 ; i<recv.process; i++) {
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part_inside+=insideOpenMP[i];
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}
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#ifdef TIME
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gettimeofday(&end,(struct timezone *)0);
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useconds=(end.tv_sec-start.tv_sec)*1000000+end.tv_usec-start.tv_usec;
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printf("\tOn %s rank %i find %lld inside in %lu useconds.\n",
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hostname,rank,(long long)part_inside,useconds);
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#else
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printf("\tOn %s rank %i find %lld inside\n",hostname,rank,
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(long long)part_inside);
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#endif
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#ifdef LONG
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rc = MPI_Isend(&part_inside, 1, MPI_LONG_LONG, 0, tag, MPI_COMM_WORLD, &RequestSend2);
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#else
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rc = MPI_Isend(&part_inside, 1, MPI_INT, 0, tag, MPI_COMM_WORLD, &RequestSend2);
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#endif
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MPI_Wait(&RequestSend2, &Stat);
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}
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MPI_Type_free(&mpi_node_type);
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MPI_Finalize();
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}
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