MATLAB: Problem when solving ODEs with ode45

ode45solving ode

Good day,
I have the following code where I simultaneously solve three second-order differential equations defined in 'ode3'.
My problem is that in the second last line in 'ode3', the denominator is Y3(3). This is the variable 'r' and is in the direction of a spring and stretches as a mass swings around at its endpoint. When I run the script I get NaN in my Y3 matrix, which then leads me to believe I'm dividing by zero some time. What I don't understand is why would that value become zero?
Any help is appreciated!
m1 = 4; %kgm2 = 6; %kgL = 1.5; %mk = 100; %N/mg = 9.81; %m/s2% --------------------------------------------------------------% Force parameters% --------------------------------------------------------------Fo = 100; %Ntf = 1;F = @(t) (t<=tf)*Fo*sin(2*pi*t/tf);ic3 = [0, 0, 0, 0, L, 0];ode3 = @(t, Y3) [Y3(4);                 Y3(5);                 Y3(6);                 (F(t) - m2*k*(L-Y3(3))*sin(Y3(2)))/m1;                 (-F(t)*cos(Y3(2)) + m2*k*(L-Y3(3))*sin(Y3(2))*cos(Y3(2)) - 2*m1*Y3(6)*Y3(5) - m1*g*sin(Y3(2)))/(m1*Y3(3));                 (-F(t)*sin(Y3(2)) + m2*k*(L-Y3(3))*sin(Y3(2))^2 + m1*Y3(3)*Y3(5)^2 + m1*g*cos(Y3(2)) + m1*k*(L-Y3(3)))/m1];           [t3, Y3] = ode45(ode3, [0, 3], ic3);

ic3 = [0, 0, 0, 0, L, 0];
(-F(t)*cos(Y3(2)) + m2*k*(L-Y3(3))*sin(Y3(2))*cos(Y3(2)) - 2*m1*Y3(6)*Y3(5) - m1*g*sin(Y3(2)))/(m1*Y3(3))
ic3 = [0, 0, 1, 0, L, 0];