It's not entirely clear (to me) what you want, but you can simply take the avg of z and plot it if that's what you want:
%%make data
[X, Y] = meshgrid(-2:0.2:2, -3:0.3:3);
Z(:, :, 1) = X + Y;
Z(:, :, 2) = 2*X + Y;
Z(:, :, 3) = 3*X + Y;
%%compute average
% simple approach:
% Z_avg = (Z1 + Z2 + Z3)/3; % for this example, Z_avg and Z2 are equivalent
% more generally:
Z_avg = mean(Z, 3);
%%plot original data
k = 1;
hf(k) = figure('WindowStyle', 'docked');
ha(k) = axes;
hold(ha(k), 'all');
hs(1) = surf(ha(k), X, Y, Z(:, :, 1));
hs(2) = surf(ha(k), X, Y, Z(:, :, 2));
hs(3) = surf(ha(k), X, Y, Z(:, :, 3));
view(3);
grid(ha(k), 'on');
title(ha(k), 'original planes');
%%plot avg.
k = 2;
hf(k) = figure('WindowStyle', 'docked');
ha(k) = axes;
hs(4) = surf(ha(k), X, Y, Z_avg);
view(3);
grid(ha(k), 'on');
title(ha(k), 'avg. plane');
It seems like you've been asking variations of this question for quite some time; is this what you were looking for? If not, what aspect are you confused about?
