Hi calvin,
If I understood you correctly - what you're looking for is the second output of regress(), which is a confidence interval. Check out the documentation for more info on how this works.. In general - it gives you a symmetrical zone around your regressor which can be regarded as the errors you refer to (although this isn't exactly a standard error).
Run this short simulation to take a closer look. I tried to keep the same variable names as in your example, so: W is the vector storing the regressors and CI, the second requested output of regress, is the confidence interval.
Y = (1:100)';
Z = randi(100,[100,2]) % get (100,2) random numbers
[W, CI] = regress(Y,Z); % get the regressors and their corresponding confidence intervals
% visualize results
figure
bar(W,'w')
xlim([0 3])
hold on
errorbar(W,[CI(1,2)-W(1), CI(2,2)-W(1)],'pr')
legend('regressor','95% C.I.','safdsad')
set(gca,'XTickLabel',{'W1','W2'})
hold off
{ If this does not answer your question, please provide: (1) the actual data you're working with and (2) a more detailed explanation of what you are looking for }
