Hello Joya,
I refactored your code to get a better idea of what it was doing, and there seem to be two issues. The main issue is that on line 39 you call "Fun3" with "q" instead of "q(i+1,:)". The second issue is that "csvread" is prepending a zero to your data. The "csvread" function is not recommended and it is recommended to use "readmatrix" or "readtable" instead.
d=dir('latlong*.csv');
n=length(d);
data=cell(n,1);
q=zeros(n,2);
for i = 1:n
data{i}=readtable(d(i).name);
z=data{i}.precipitation(data{i}.precipitation >= 0.001);
figure(i);
hold on
h=histogram(z,1000,'Normalization','pdf');
no=h.NumBins;
counts=h.Values';
edge=h.BinEdges(2:end)';
Fun3=@(q,edge) ((1./(edge.*q(2).*sqrt(2*pi))).*exp(-((log(edge)-q(1)).^2)./(2*q(2)^2)));
q0=[2,2];
q(i,:)=lsqcurvefit(Fun3,q0,edge,counts);
plot(edge,Fun3(q(i,:),edge));
hold off
xlabel('Observation')
ylabel('Probability Density')
legend('histogram','log')
end
Hope this helps, let me know if I misunderstood anything.
