Here are some suggestions. To see what each line is doing, remove the ";".
%Store your data in cells so you can use loops. Example:
VarName = cell(1, 5);
for j = 1:5
VarName{j} = randi(175, 100, 1);
end
%Label your variables with 1st-letter cap, to prevent overwriting matlab
%functions. For instance, you had "mean = (af1+af2+..." which would
%override the "mean.m" matlab function! This leads to a lot of bugs.
Bin = 0:3:175;
AF = zeros(length(Bin), length(VarName)); %Store your binned data in a matrix
for j = 1:5
AF(:, j) = histc(VarName{j}, Bin);
end
Mean = mean(AF, 2);
%error=sqrt(((mean-af1).^2+(mean-af2).^2+(mean-af3).^2+(mean-af4).^2+(mean-af4).^2)/5
%Notice you have a typo. (mean-af4).^2 comes twice.
%To prevent coding error, use following practices:
Error = sqrt(sum((Mean-AF).^2, 2)/5)
%Error = std(AF, [], 2); %Did you want standard dev?
%Plot data and store the handles as variables. Makes it easier to adjust.
Bx = bar(Bin, Mean, 'histc');
hold on
Shift = diff(Bin(1:2))/2; %Need to shift your error bar to center it
Ex = errorbar(Bin+Shift, Mean, Error, 'k', 'linestyle', 'none');
hold off
%Adjust plots via those handles. Example:
Bx.FaceColor = [1 1 1]; %Make bars white
Ex.Color = [1 0 0]; %Make error bars red
