Hi!
I don't understand why the x and y spacing depends on the number of modes/frequencies.
Take a look at the following code:
L_x = 27.4e-3; %membrane width (m)
L_y = 27.4e-3; %membrane height (m)
N_x = 5; %no. of eigenfreqs considered in x dimension
N_y = 10; %no. of eigenfreqs considered in y dimension
N = N_x*N_y; %total no. of eigenfreqs considered
NumX = 50; % number of mapping points in x-direction
NumY = 50; % number of mapping points in y-direction
% create X and Y array in 2d
[X,Y] = meshgrid(...
(linspace(0.5*L_y/NumY, L_y - 0.5*L_y/NumY, NumY)), ...
(linspace(0.5*L_x/NumX, L_x - 0.5*L_x/NumX, NumX)));
% modify X and Y array for 3d
XFull = repmat(X, [1 1 N]);
YFull = repmat(Y, [1 1 N]);
% create mode array for X
Mx = ones(NumX, NumY, N_y);
MxFull = [];
for n = 1:N_x
MxFull = cat(3, MxFull, n*Mx);
end
% create mode array for Y
My = ones(NumX, NumY);
MyFull = [];
for n = 1:N_y
MyFull = cat(3, MyFull, n*My);
end
MyFull = repmat(MyFull, [1 1 N_x]);
% modes for each direction
Wx_n = arrayfun(@(x,mx) sin(x .* (mx *pi/L_x)), XFull, MxFull);
Wy_n = arrayfun(@(y,my) sin(y .* (my *pi/L_x)), YFull, MyFull);
% superposition of modes
W_n = Wx_n .* Wy_n;
% plot
figure(1); cla
surface(W_n(:,:,23));
