Array not updating values in MATLAB - matlab

Question

So I have the following code in MATLAB that implements a differences equation. However the entries of the array not seem to be updated at every iteration. I don't know how such a simple thing is getting messed up, probably it is a silly mistake. Here is the code:
K12=0.3*3600;
K21=0.2455*3600;
K10=0.0643*3600;
V1=3110;
V2=3110;
delta=1000;
h=1;
n_zeros=5;
val_dose=3;
n_doses=10;
n_dias=n_doses+n_doses*n_zeros;
vec_doses=val_dose*ones(1, n_doses);
vec_doses=upsample(vec_doses, n_zeros+1);
t=zeros(1, n_dias);
c1=zeros(1, n_dias*h);
c2=zeros(1, n_dias*h);
c1(1*h)=0;
c2(1*h)=0;
A1=(-K12-K10)/V1;
B1=K21/V1;
D1=delta/V1;
A2=K12/V2;
B2=-K21/V2;
for k=1:(n_dias-1)
t(k+1)=k;
c1((k+1)*h)=c1(k*h)+h*A1*c1(k*h)+h*B1*c2(k*h)+h*D1*vec_doses(k);
c1((k+1)*h)=c2(k*h)+h*A2*c1(k*h)+h*B2*c2(k*h);
end
And after this both c1 and c2 are arrays of just zeros, just like when they are initiazed. Any guess?