%Temp distribution in a cylinder
h=1;
r=[5:h:10];
n=length(r);
T(1)=120;
T(n)=60;
R=r((1+1):(n-1));
nn=length(R);

A=zeros(nn,nn);
B=zeros(nn,1);

for k=1:nn
A(k,k)=-2/h^2;

if k==nn
B(k,1)=-(1/h^2+1/(2*h*R(k)))*T(n);
else
A(k,k+1)=(1/h^2+1/(2*h*R(k)));
end

if k==1
B(k,1)=-(1/h^2-1/(2*h*R(k)))*T(k);
else
A(k,k-1)=(1/h^2-1/(2*h*R(k)));
end
end