return(sqrt(v3_absolute_square(a)));
}
+int v3_per_bound(t_3dvec *a,t_3dvec *dim) {
+
+ double x,y,z;
+
+ x=0.5*dim->x;
+ y=0.5*dim->y;
+ z=0.5*dim->z;
+
+ if(a->x>=x) a->x-=dim->x;
+ else if(-a->x>x) a->x+=dim->x;
+ if(a->y>=y) a->y-=dim->y;
+ else if(-a->y>y) a->y+=dim->y;
+ if(a->z>=z) a->z-=dim->z;
+ else if(-a->z>z) a->z+=dim->z;
+
+ return 0;
+}