```#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <mpc.h>
#define DELTA (0.5)

typedef struct {
double len;
double wid;
double hei;
double mass;
} rail;

nettype HeteroNet(int n, double v[n]) {
coord I=n;
node {I>=0: v[I];};
parent [0];
};

double Density(double x, double y, double z) {
return 6.0*sqrt( exp( sin( sqrt( x*y*z ) ) ) );
}

double RailMass(double len, double wid, double hei, double delta) {
double mass, x, y, z;
for(mass=0., x=0.; x<len; x+=delta)
for(y=0.; y<wid; y+=delta)
for(z=0.; z<hei; z+=delta)
mass += Density(x,y,z);
return mass*delta*delta*delta;
}

int [*]main(int [host]argc, char **[host]argv) {
repl N=3;

if(argc>1)
N = [host]atoi(argv[1]);

if(N>0) {
static rail [host]steel_hedgehog[[host]N];
repl double volumes[N], [host]start;
int [host]i;
repl j;

for(i=0; i<[host]N; i++) {
steel_hedgehog[i].len = 200.*(i+1);
steel_hedgehog[i].wid = 5.*(i+1);
steel_hedgehog[i].hei = 10.*(i+1);
}

start = [host]MPC_Wtime();

for(j=0; j<N; j++)
volumes[j] =
steel_hedgehog[j].len * steel_hedgehog[j].wid * steel_hedgehog[j].hei;

recon RailMass(20., 4., 5., 0.5);
{
net HeteroNet(N, volumes) mynet;
[mynet]: {
rail myrail;

myrail = steel_hedgehog[];
myrail.mass =
RailMass(myrail.len, myrail.wid, myrail.hei, DELTA);
MPC_Printf("Rail #%d is %gcm x %gcm x%gcm and weights %g kg\n",
I coordof mynet, myrail.len, myrail.wid,
myrail.hei, myrail.mass/1000.0);
[host]printf("The steel hedgehog weights %g kg\n",
[host]((myrail.mass)[+])/1000.0);
}
}
[host]printf("\nIt took %.1f seconds to run the program.\n",
[host]MPC_Wtime()-start);
}
else
[host]printf("Wrong input (N=%d)\n", [host]N);
}
```