use r³ !

diff --git a/zentral.c b/zentral.c
index cf071cd..e7a9430 100644 (file)
--- a/zentral.c
+++ b/zentral.c
@@ -46,7 +46,7 @@ int main(int argc,char **argv) {
 
  /* loop */
  for(i=0;i<steps;i++) {
 
  /* loop */
  for(i=0;i<steps;i++) {

-  r_3=x_p*x_p+y_p*y_p;
+  r_3=sqrt(x_p*x_p+y_p*y_p)*(x_p*x_p+y_p*y_p);

   f_x=-alpha*x_p/r_3; f_y=-alpha*y_p/r_3;
   x=x_p+vx_p*tau; y=y_p+vy_p*tau;
   vx=vx_p+f_x*tau; vy=vy_p+f_y*tau;
   f_x=-alpha*x_p/r_3; f_y=-alpha*y_p/r_3;
   x=x_p+vx_p*tau; y=y_p+vy_p*tau;
   vx=vx_p+f_x*tau; vy=vy_p+f_y*tau;