I created an 3D sinusoidal surface. And want to add a normally distributed random noise of zero mean and 0.03mm standard deviation. But it said error on the line with*. Subscripted assignment dimension mismatch. could someone help me check it please

%3D sinusoidal surface dx=0.001; %spacing in x in mm dy=0.001; %number of points along x and y nx=128; ny=128; %n=8000; %generate array of x & y x=(0:1:nx-1)*dx; y=(0:1:ny-1)*dy; for j=1:ny for i=1:nx z(j,i)=2*sin(2*pi*x(i)/0.064)+normrnd(0,0.03*ones(nx,1)); end end z=z-mean(mean(z));%shift to 0 mean mesh(x,y,z)

Answer 1

[Youssef Khmou]

Jianxiang,

As you use x,y loops , at each iteration the CPU computes only one scalar while you used the function normrnd of size 128*1, you can adjust your method :

%3D sinusoidal surface
dx=0.001; %spacing in x in mm 
dy=0.001; %number of
%points along x and y 
nx=128; ny=128; %
n=8000; %generate array of x & y 
x=(0:1:nx-1)*dx; 
y=(0:1:ny-1)*dy; 
for j=1:ny 
  for i=1:nx 
      z(j,i)=2*sin(2*pi*x(i)/0.064)+normrnd(0,0.03);
  end
end
z=z-mean(mean(z));%shift to 0 mean mesh(x,y,z)

Or you can simply add the Gaussian noise like the following :

Z=z+normrnd(0,0.03,nx,ny);

Answer 2

[muna majeed]

please can help me to add noise to 3d mesh triangle