#include <iostream>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sstream>
#include <math.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
using namespace std;


long double fact(int n)
{
	if (n<0)
		return 0;
	if (n == 0)
		return 1;
	else
		return n*fact(n - 1);
}

double frenel1(double x)
{	double eps=0.0001;
	double an = x*x*x / 3; double sum = an;
	int i = 1;
	while (fabs(an)>eps)
	{
		an = pow(-1, i)*pow(x, 4 * i + 3) / ((4 * i + 3)*fact(2 * i + 1));
		sum += an;
		i++;
	}
	return sum;
}


double frenel2(double x)
{	double eps=0.0001;
	double an = x; double sum = an;
	int i = 1;
	while (fabs(an)>eps)
	{
		an = pow(-1, i)*pow(x, 4 * i + 1) / ((4*i + 1)*fact(2*i));
		sum += an;
		i++;
	}
	return sum;
}


int main(int argc, char* argv[])
{
	double x,r1,r2;
	int sock, listener,test=1;
    struct sockaddr_in addr;
    listener = socket(AF_INET, SOCK_STREAM, 0);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(9535);
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    setsockopt(listener,AF_INET,SO_REUSEADDR,&test,sizeof(int));
    bind(listener, (struct sockaddr *)&addr, sizeof(addr));
    listen(listener, 1);
    while(1)
    {
        sock = accept(listener, NULL, NULL);
        recv(sock, &x, sizeof(double), 0);
        if (x==-1){  shutdown(sock,1); break; };
        r1 = frenel1(x);
	r2 = frenel2(x);
        send(sock, &r1, sizeof(double), 0);
	send(sock, &r2,sizeof(double),0);
	close(sock);
    }
    
    return 0;
}

Клиент

#include <cmath>
#include <iostream>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sstream>
#include <math.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>


using namespace std;

int main(int argc, char* argv[])
{
	if ((argc>1)&&(strcmp(argv[1],"--help")==0)) 
	{
	 cout<<"Integrali Frenelya\n";
	 cout<<"Ostanovka servera -e.\n";
	 return 0;
	}
	
	int sock;
    struct sockaddr_in addr;
    sock = socket(AF_INET, SOCK_STREAM, 0);
    addr.sin_family = AF_INET;
    addr.sin_port = htons(9535);
    addr.sin_addr.s_addr =htonl(INADDR_LOOPBACK);
    if (connect(sock, (struct sockaddr*)&addr, sizeof(addr))<0) {cout<<"Error connect\n"; return 0;}
       
   
	double x;
	double r1,r2;
	if ((argc>1)&&(strcmp(argv[1],"-e")==0)) { x=-1; }
	else
	{
	 cout<<"X= ";
	 cin>>x;
	}
	send(sock,&x,sizeof(double),0);
	if(x==-1){
	    shutdown(sock,0);
	}
	else
		{
		recv(sock, &r1, sizeof(double), 0);
		recv(sock,&r2,sizeof(double), 0);
		cout<<"S("<<x<<") == "<<r1<<endl;
		cout << "R("<<x<<")=="<<r2<<endl;
	}
	close(sock);
    return 0;
}