MATLAB: How to make a for loop with two diferent indexes

for loop

%My problem:
syms w;
for i=1:20
    lam=i;
    xi = fsolve(@(w) -tan(w/2) + w/2-(4./(lam))*(w/2).^3,[pi()-0.1 3*pi()-0.1]);
    X(i) = xi(2)/pi()
end
%This is fine, but now I want to break the intervals in smaller ones:
syms w;
for i=1:0.2:20
    lam=i;
    xi = fsolve(@(w) -tan(w/2) + w/2-(4./(lam))*(w/2).^3,[pi()-0.1 3*pi()-0.1]);
    X(i) = xi(2)/pi()
end
%And I want the values of xi(2)/pi() to be saved in a vector, but it want let me. I understand why, but I can't resolve it.
%Thank you very much to you all.

Best Answer

syms w; 
cnt = 1:.2:20;
for ii=1:length(cnt)
    xi = fsolve(@(w) -tan(w/2) + w/2-4/ii*(w/2).^3,[1 3]*pi-.1);
    X(ii) = xi(2)/pi;
end
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