MATLAB: Output argument not assigned

Question

Dear community,I have been continually hitting the following error in my code:

--
Output argument "var_ap" (and maybe others) not assigned during call to
"mf_field".
"Error in mf_srex (line 144)
[~, var_srex] = mf_field(var, mask);"

Below is the part of the code to which it is referring:

    if    length(size(var)) == 2
        % get field mean
        var_ap = nanmean(nanmean(var       .* area      )) ./ nanmean(nanmean(area      ));
        var_mp = nanmean(nanmean(var(mask) .* area(mask))) ./ nanmean(nanmean(area(mask)));
    elseif length(size(var)) == 3
        % get field mean for masked pixel
        var_ap = NaN(size(var,3),1);
        var_mp = NaN(size(var,3),1);
        for j = 1:size(var,3)
            vari        = var(:,:,j);
            var_ap(j,1) = nanmean(nanmean(vari       .* area      )) ./ nansum(nanmean(area      ));
            var_mp(j,1) = nanmean(nanmean(vari(mask) .* area(mask))) ./ nansum(nanmean(area(mask)));
        end
    end

Please can somebody offer some advice?

Thanks for your time.

Answer 1

For some reason, you're never assigning anything to var_srex. To fix, just assign it to anything, such as 0 or null, as the very first line of mf_field :

var_srex = [];

Of course you may then get some error where var_srex is null and you expected something else, but you won't also get the error that var_srex is not assigned.