How to use the previous data in the next calculates? - matlab

Question

In this code I used the Thomas algorithm to calculate V(k,i) and ni(k,i).
Thomas algorithm is based on two steps:
the first is the forward elimination (see first loop (for i=1:nx).
the second is backward elimination (see second loop (for
i=nx-1:-1:1).
in the first step I calculate the matrix coefficients and in the second loop I calculate the unknown V(k,i).
my problem is:
how to calculate coefficient dp(k,i) which depends on ni(k,i), but
ni(k,i) is in the last loop?
maybe the question is how to use data of the previous calculation in
the next calculation?
K is the time iteration.
i is the space iteration.
python
for k=1:nt
for i= 1:nx
ap(k,i)= 1;
bp(k,i)= -2;
cp(k,i)= 1;
dp(k,i)= -(dx.^2).*(ni(k,i));
alphap(k,i)=-cp(k,i)./(bp(k,i) + ap(k,i).*alphap(k,i-1));
betap(k,i)=(dp(k,i)-ap(k,i).*betap(k,i-1))./(bp(k,i)+ ap(k,i).*alphap(k,i-1));
end
V(k,nx) = betap(k,nx);
for i=nx-1:-1:1
V(k,i)=alphap(k,i).*V(k,i+1) + betap(k,i);
Ti1= (V(k,i+1)-V(k,i));
Ti2= (V(k,i)-V(k,i-1));
end
for i=1:nx
ai(k,i)= (Di.*exp(Ti2).*Ti2)./((dx.^2).*(1-exp(Ti2)));
bi(k,i)= 1/dt-(Di.*(exp(Ti1).*Ti1))./(dx^2);
ci(k,i)= (Di.*Ti1)./((dx^.2)*(1-exp(Ti1)));
di(k,i)= (1/dt).*ni(k,i)+Ki.*nn.*ne(k,i);
alphai(k,i)=-ci(k,i)./(bi(k,i) + ai(k,i).*alphai(k,i-1));
betai(k,i)=(di(k,i)-ai(k,i).*betai(k,i-1))./(bi(k,i)+ ai(k,i).*alphai(k,i-1));
end
ni(k,nx) = betai(k,nx);
for i=nx-1:-1:1
ni(k,i)=alphai(k,i).*ni(k,i+1) + betai(k,i);
end
end