symbolic system of equation

Hi,

It is first time studying on symbolic expressions. I face ''error using zeros'' error when I run following code. Is there anyone can help me about this ?

PS. I added equations as image.

syms gamma w u aoa pi dt b rho

gamma=sym(zeros(i,1));
w=sym(zeros(i,1));
l=sym(zeros(i,1));
for i=1:1:5
    if i==1
%         rhs1(i)=0
%         rhs2(i)=-u*aoa
        eqn1=gamma(i)+w(i)==0;
        eqn2=gamma(i)+w(i)/(2*pi*((b/2)+(u*dt)/2))==-u*aoa;
        
    else
        rhs1=0;
        rhs2=-u*aoa;
        for j=1:1:i-1
             rhs1=-w(j)+rhs1;
             rhs2=-w(j)/(2*pi*((b/2)+(((2*i-2*j)+1)*u*dt)/2));
             eqn1=gamma(i)+w(i)==rhs1;
             eqn2=gamma(i)+w(i)/(2*pi*((b/2)+(u*dt)/2))==rhs2;
             eqns=[eqn1,eqn2];
             sol=vpasolve(eqns,[gamma(i),w(i)]);
             sol.gamma;
             sol.w;
        end
    end
end

if i==1
    l(i)=2*b*rho*gamma(i)+rho*u*gamma(i);
else
    l(i)=2*b*rho*(gamma(i)-gamma(i-1))+rho*u*gamma(i);
end

Answer 1

[M]

First problems on lines 2 to 4:

gamma=sym(zeros(i,1));
w=sym(zeros(i,1));
l=sym(zeros(i,1));

i is not yet defined.