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99 lines
2.0 KiB
C
99 lines
2.0 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include "mpi.h"
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void firstderiv1Dp_vec(int n, double dx, double *f,double *fx, int mynode, int totalnodes);
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double fun(double x);
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double funprime( double x);
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int main(int argc, char **argv){
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double globala,globalb,a,b,dx,*f,*fx, error;
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int n, mynode, totalnodes;
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MPI_Status status;
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MPI_Init( &argc, &argv );
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MPI_Comm_rank( MPI_COMM_WORLD, &mynode );
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MPI_Comm_size( MPI_COMM_WORLD, &totalnodes );
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n = 20;
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globala = 0;
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globalb = 1;
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a = globala + ((double) mynode)*(globalb - globala)/( (double) totalnodes);
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b = globala + ((double) mynode+1)*(globalb - globala)/( (double) totalnodes);
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f = (double *) malloc(sizeof(double)*(n));
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fx = (double *) malloc(sizeof(double)*(n));
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dx = (b-a)/((double) n);
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for( int i = 0; i < n; i++){
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f[i] = fun(a+((double) i)*dx);
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}
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firstderiv1Dp_vec( n, dx, f, fx, mynode, totalnodes);
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error = 0.0;
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for(int i = 0; i < n; i++){
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error += pow( fx[i]-funprime(a+((b-a)*((double) i))/((double) n)),2.0);
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}
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error = sqrt(dx*error);
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printf("Node %d ||f' - fx||_2 = %e\n",mynode,error);
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free(f);
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free(fx);
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MPI_Finalize();
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return 0;
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}
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void firstderiv1Dp_vec(int n, double dx, double *f,double *fx, int mynode, int totalnodes){
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double scale = 1.0/(2.0*dx);
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double mpitemp;
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MPI_Status status;
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if(mynode == 0){
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fx[0] = (-3.0*f[0] + 4.0*f[1] - f[2])*scale;
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}
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if(mynode == (totalnodes-1)){
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fx[n-1] = (3.0*f[n-1] - 4.0*f[n-2] + f[n-3])*scale;
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}
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for(int i=1;i<n-1;i++){
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fx[i] = (f[i+1]-f[i-1])*scale;
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}
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if(mynode == 0){
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mpitemp = f[n-1];
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MPI_Send();
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MPI_Recv();
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fx[n-1] = (mpitemp - f[n-2])*scale;
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}
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else if(mynode == (totalnodes-1)){
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MPI_Recv();
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fx[0] = (f[1]-mpitemp)*scale;
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mpitemp = f[0];
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MPI_Send();
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}
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else{
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MPI_Recv();
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fx[0] = (f[1]-mpitemp)*scale;
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mpitemp = f[0];
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MPI_Send();
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mpitemp = f[n-1];
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MPI_Send();
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MPI_Recv();
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fx[n-1] = (mpitemp-f[n-2])*scale;
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}
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return;
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}
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double fun(double x){
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return(sin(x));
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}
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double funprime( double x){
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return(cos(x));
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}
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