Black hole saga

r=Math.sqrt(x*x+y*y+z*z);   //radius
   accx= -a*x/(r*r*r);                   //acceleration in x direction
   accy= -a*y/(r*r*r);                   //        "    in y direction
   accz= -a*z/(r*r*r);                   //        "    in y direction
   vx+=accx*dt;
   vy+=accy*dt;
   vz+=accz*dt;
   x+=vx*dt;
   y+=vy*dt;
   z+=vz*dt;
   Moveball(1, x, y, z);             //Move the blue satellite

s=Math.sqrt((x-mx)*(x-mx)+(y-my)*(y-my)+(z-mz)*(z-mz)); 
   mr=Math.sqrt(mx*mx+my*my+mz*mz);   //radius
   maccx= -a*mx/(mr*mr*mr)+(x-mx)/s/10;                   //acceleration in x direction
   maccy= -a*my/(mr*mr*mr)+(y-my)/s/10;                   //        "    in y direction
   maccz= -a*mz/(mr*mr*mr)+(z-mz)/s/10;                   //        "    in y direction
   
   
   
   mvx+=maccx*dt;
   mvy+=maccy*dt;
   mvz+=maccz*dt;
   mx+=mvx*dt;
   my+=mvy*dt;
   mz+=mvz*dt;
   Moveball(2, mx, my, mz);             //Move the missile

document.inputs.radius.value = r;   //Show the values
   document.inputs.posx.value = x;   
   document.inputs.posy.value = y;   
   document.inputs.posz.value = z;

document.inputs.mradius.value = mr;   //Show the values
   document.inputs.mposx.value = mx;   
   document.inputs.mposy.value = my;   
   document.inputs.mposz.value = mz;  
   document.inputs.sep.value = s;

if(running){setTimeout('StepModel()',10);}