MATLAB: Hello everyone, I wrote a code for computing an equation and plot in 3-D (surf)? but it didn’t give me a right answer! what is the problem? Also the plot is attached.

Question

w3=0:0.1:5;

t=0:0.01:5;

w=107.36; d=150; x=410;

[a,b]=meshgrid(w3,t);

z=abs(((4.22*(10.^-3))*((a).^2)/((w.^2)-(a.^2))))*sin((pi*d)/820)*sin((pi*x)/820)*sin((a).*b);

surf(a,b,z)

The error is:

Warning: Rank deficient, rank = 1, tol = 9.150206e-09.

> In vibrationalresponse3d (line 15)

Answer 1

When dealing with arrays, unless you specifically intend too do matrix operations, always use element-wise operations (the dot operator).

Try this:

w3=0:0.1:5;
t=0:0.01:5;
w=107.36; d=150; x=410;
[a,b]=meshgrid(w3,t);
z=abs((4.22E-3)*(a.^2)./((w.^2)-(a.^2))).*sin((pi*d)/820).*sin((pi*x)/820).*sin(a.*b);
figure
surf(a,b,z, 'EdgeColor','none')

producing:

Also, eliminating the edge line color makes the patch faces visible.