surf() to bar3() "Matrix dimensions must agree, not rendering mesh"

This is my attempt to simulate the water surface. It works fine when I use the surf() function. But when I change it to bar3(), this error occurs: "Matrix dimensions must agree, not rendering mesh". Can some one please tell me how to fix this? Thank you. Here's my code:

          n=60;
          i = 2:n-1;
          j = 2:n-1;
          H = ones(n,n);

          Dropx=30; %x and y coordinate of the droplet
          Dropy=30;
          width=20;
          r=width/2;
          dt=0.1;
          dx=0.3;

          %%%add droplet to the surface %%%
          [x,y] = ndgrid(-1.5:(2/(width/1.5-1)):1);
          D = 8*exp(-5*(x.^2+y.^2));
          w = size(D,1);
          i2 = (Dropx-r):w+(Dropx-r)-1;
          j2 = (Dropy-r):w+(Dropy-r)-1;
          H(i2,j2) = H(i2,j2) + D;

          oldH=H;
          newH=H;
          h=surf(newH); % cannot change this to bar3
          axis([1 n 1 n -2 8]);
          k=0.2; %damping constant
          c=2;   %wave speed

          while 1==1
              newH(i,j)=H(i,j)+(1-k*dt)*(H(i,j)-oldH(i,j))-...
              dt^2*c^2/dx^2*((4*H(i,j)-H(i+1,j)-H(i-1,j)-H(i,j+1)-H(i,j-1))...
              +0.4*(4*H(i,j)-H(i+1,j+1)-H(i+1,j-1)-H(i-1,j+1)-H(i-1,j-1)));
              set(h,'Zdata', newH(i,j));
              oldH=H;
              H=newH;
              pause(0.05);
          end

[mcan06]

Could you share with me if you had any reference which you derived the newH part of this code?

Answer 1

[Star Strider]

That has to be the coolest simulation I’ve seen posted on MATLAB Answers!

I figured out how to make bar3 work.

1. Comment-out (or delete) this line ( 5 lines above the while loop ) and the axis line just below it:

%           h=surf(newH); % cannot change this to bar3

2. Comment out (or delete) this line in the while loop:

%               set(h,'Zdata', newH(i,j));

3. Insert these lines just below the commented-out ‘set(h, 'ZData' ...’ line:

                h = bar3(newH);
  %               h=surf(newH);
                axis([1 n 1 n -2 8]);

Then choose either bar3 or surf to see the result.

[Huy]

Thank you for your answer. So basically we have to replott the data at every timestep. This will be slow but it solves the problem. Thank you.

[Star Strider]

My pleasure!

You only have to replot it if you use bar3. Your original code works fine with surf. I didn’t time it, but I didn’t notice a difference between the original and the code revised to use bar3. (Actually, I was so awed just watching it that I didn’t notice any difference in performance.)