calc int

#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <mpi.h>
// functia de integrat f(x)
double f(double x)
{
return 4.*sqrt(1.-x*x);
}

double
calculeaza_integrala (double a ,double b , long N )
{
int i ;
double dx = ( b - a )/( double ) N;
double x ;
double s ;
s = 0;
for ( i =0; i < N ; i ++)
{
x = a + ( double ) i * dx + dx /2.;
s = s + f ( x);
}
s = s * dx ;
return s ;
}
int main ( int argc , char ** argv )
{
int Np , rank;
long i ;
// limitele de integrare
double a , b ;
double N ;
double c1 , c2;

long Ni;
MPI_Init ( &argc , &argv);
MPI_Comm_size(MPI_COMM_WORLD, &Np);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
// MASTER -- rang 0
if(rank==0)
{
double s,I;
// input
a = 0.;
b= 1.;
N= 10000;
// trimite a, b catre procesele de tip worker
for(i=1;i<Np;i++)
{
// trimite intervalul de integrare [c1,c2]
c1=a+ (b-a)/(double)(Np-1) * (double)(i-1);
c2=a+ (b-a)/(double)(Np-1) * (double)i;
Ni= (long) ( (double)N/(double)(Np-1) );
MPI_Send( &c1, 1,MPI_DOUBLE,i, 0,MPI_COMM_WORLD);
MPI_Send( &c2, 1,MPI_DOUBLE,i, 0,MPI_COMM_WORLD);
MPI_Send( &Ni, 1,MPI_LONG,i, 0,MPI_COMM_WORLD);
}
// primeste rezultatele integralelor si calculeaza rezultatul final
for(i=1;i<Np;i++)
{
MPI_Recv( &s, 1,MPI_DOUBLE,MPI_ANY_SOURCE, 0,MPI_COMM_WORLD,MPI_STATUS_IGNORE);
I=I+s;
}
// afiseaza rezultatul integralei
printf("I = %f \n",I);
}
// WORKERS -- rangurile 1, 2, ... ,
else
{
double s;
//primeste intervalul de integrare
MPI_Recv( &c1, 1,MPI_DOUBLE, 0, 0,MPI_COMM_WORLD,MPI_STATUS_IGNORE);
MPI_Recv( &c2, 1,MPI_DOUBLE, 0, 0,MPI_COMM_WORLD,MPI_STATUS_IGNORE);
MPI_Recv( &Ni, 1,MPI_LONG, 0, 0,MPI_COMM_WORLD,MPI_STATUS_IGNORE);
// calculeaza integrala pe intervalul [c1,c2]
s=calculeaza_integrala(c1,c2,Ni);
// trimite rezultatul catre MASTER
MPI_Send( &s, 1,MPI_DOUBLE, 0, 0,MPI_COMM_WORLD);
}
MPI_Finalize();
return 0;
}