#include <math.h>
#include <iostream>
using namespace std;
 
class Vec3d
{
public:
    double x, y, z;
 
public:
    Vec3d() {};
    Vec3d(double a, double b, double c) : x(a), y(b), z(c) {}
};
 
double randf()
{
    return ((double)rand()/(double)(RAND_MAX));
}
 
Vec3d vRand()
{
    double theta = 2.0 * M_PI * randf();
    double phi = acos(2.0 * randf() - 1.0);
    double sinphi = sin(phi);
    return Vec3d(cos(theta) * sinphi, sin(theta) * sinphi, cos(phi));
}
 
int main()
{
 
	Vec3d v = vRand();
 
	printf("x = %f\n", v.x);
	printf("y = %f\n", v.y);
	printf("z = %f\n", v.z);
 
	return 0;
}

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