Ball Collision Simulation

This matlab function simply simulates the collision of balls. Each ball has three properties: radius, mass and charge quantity. The program detects possible collisions in each frame.
Examples:
>>SphereCollider([1.25 1 0;1.25 1 0],[-5 0 0;1.25 0 0],[3 0 0;0 0 0],...
'g',0,'debug','off','t',25)
>>SphereCollider('g',0,'debug','off')
>>SphereCollider([1 1 0],[0 0 0],[0 0 0],...
'GravityVec',[0 -1 0],'GroundPoint',[0 -10 0],...
'g',1,'dt',0.025,'debug','on','t',20)
>>SphereCollider([0.5 1 0],[-5 0 0],[0 1.15 0],...
'sphere',[2 0 0 0],'GravitySrc',[10 0 0 0],...
'G',-1,'g',0,'debug','off','t',300)
The movement of walls is defined by anonymous functions of time. The corresponding input argument is a cell that contains handles of such functions,
{...
{@(t) vx, @(t) vy, @(t) vz},... velocity of the first wall
{@(t) vx, @(t) vy, @(t) vz},... velocity of the second wall
...
}
For example:
f1 = @(t) 0.2*heaviside(t)-0.2*heaviside(t-20);
f2 = @(t) 0;
v = {{f1,f2,f2}};
SphereCollider([1 1 0;1 1 0;1 1 0],[0 4 0;0 -4 0;-4 0 0],[2 -2 0;1 1 0;2 4 0],'sphere',[2 0 0 0],'g',0,'debug','off','t',250,'sphere_velocity',v)