How to write N*1 Matrix with M-1 element

How to write N*1 Matrix with M-1 element and find the Ax = b lineer system of equation

t(1)=0;
k=.01
N=1/k
h=1.5;
z=k/h;
m=k/h^2;
M=60/h
S(1)=70;
sigma=.1;
r=0.12;
K=100;

for i=2:M
    S(i+1)=S(i)+h;
end

for j=2:N
    t(j+1)=t(j)+k;
end

for i=1:M
alpha(i)=sigma^2*m*S(i)^2
beta(i)=r*(z/2)*S(i)
end

% v(i)=[(1-alpha(i))]
% y(i)=[(beta(i)+(alpha(i)/2))]
% z(i)=[((alpha(i)/2)-beta(i))]

for i=1:M
A=full(gallery('tridiag',M,(1-alpha(i)),(beta(i)+(alpha(i)/2)),((alpha(i)/2)-beta(i))))
end

[Rik]

Your question is still unclear to me. The part ending with a question mark doesn't seem to have a lot to do with the rest of your question.

Can you explain a bit further what you mean?

[Cagin Keskin]

I am trying to apply finite difference method with lineer system equation Ax = b but ı dont know how to write x and b code on matlab