Parallel Integration Slave Some PVM Examples

```#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <pvm3.h>
#include "func.h"

/*
* Find the area to the tolerance.
*/
static double find(double x1, double y1, double x2, double y2, double tol)
{
/* Compute the midpoint from the funcion. */
double midx = (x1 + x2) / 2;
double midy = f(midx);

/* Estimate the midpoint from the y value. */
double midest = (y1 + y2) / 2;

/* See if we're getting close. */
if(fabs(midy - midest) <= tol)
/* Will do.  Compute the area using the midy, since we
found it.  Two trapazoids algebraically simplified. */
return 0.25*(x2-x1)*(y1 + y2 + 2*midy);
else
/* Subdivide and try again. */
return find(x1, y1, midx, midy, tol) +
find(midx, midy, x2, y2, tol);
}

#define INITMAX 20

main()
{
int ptid;
char buf[100];
int argc;
char *argv[INITMAX];

ptid = pvm_parent();

pvm_recv(ptid, 1);
pvm_unpackf(" %d ", &argc);
int n;
for(n = 0; n < argc; n++) {
int len;
pvm_upkint(&len, 1, 1);
argv[n] = malloc(len + 1);
pvm_upkstr(argv[n]);
}
finit(argc, argv);

/* Find our portion. */
double startx, endx, tol;
int rn = pvm_recv(ptid, 2);
pvm_unpackf("%lf %lf %lf ", &startx, &endx, &tol);

/* Compute it and send it. */
double res = find(startx, f(startx), endx, f(endx), tol);

// Return the result.