from visual import *
A=10.0
r0=0.05
def newforce(a,b):
	diff=(1.0/r0)*(a.pos-b.pos)
	return A*norm(diff)*exp(-diff.mag2)
	


def totalforce(a,objlist):
    force=vector(0,0,0)
    for ball in objlist:
# no self-interaction!
        if (ball!=a):
            force=force+newforce(a,ball)
    return force