If you define a function with output arguments and you then want to get those outputs then of course you will also need to call the function with those output arguments. This is true for every kind of function, including nested functions.
function [..] = rodent_trial2(rodent, trial_no)
[~,~,out] = fn_all_data(); % you need to call the function with the output arguments!!!
idx = out.X>=0 & out.Y>=0;
Q1 = out(idx,:);
..
%nested function
function [X, Y, all_data] = fn_all_data() % if you defined output arguments here.
% code
all_data = .. whatever
end
end
But I suspect that you were actually attempting to share the data via the parent workspace, perhaps something like this.
function [..] = rodent_trial2(rodent, trial_no)
all_data = []; % must be defined in the parent workspace before calling nested function!
fn_all_data() % no output arguments!
idx = all_data.X>=0 & all_data.Y>=0;
Q1 = all_data(idx,:);
..
%nested function
function fn_all_data() % no output arguments!
% code
all_data = .. whatever
end
end
This is explained here: https://www.mathworks.com/help/matlab/matlab_prog/nested-functions.html#f4-73993
