#include <math.h>

void main()
{

    double x = 0.5;
    double y = 0.05;
    double z = 0.5;
    double r = 0.05;

    double x1 = 0.5;
    double y1 = 0.15;
    double z1 = 0.5;
    double r1 = 0.05;

    double dx = x-x1;
    double dy = y-y1;
    double dz = z-z1;

    double d = sqrt(dx*dx+dy*dy+dz*dz);

    double c = r+r1 - d;
}

c = 1.3877787807814e-017 почему???

условия: AMD Athlon(TM) XP 2200+, w2k, VC++6.0