3D-plot of circular elements inside a matrix

Hi all,

I want to use meshc command and draw some elements inside a matrix that the elements indexes make a circle. for example in matrix A , I want to draw just the elements greater than 0:

A=[ 0 0 2 0 0; 
    0 1 3 2 0
    3 4 2 1 3
    0 2 3 5 0
    0 0 4 0 0];

I want to eliminate the elements that are zero and draw the other elements in 3D. by doing so, we can clearly see the X-Y plane contours in 3-D plot.

Any reply is really appreciated.

Thanks

[Sean de Wolski]

Mehdi replies:

"Is there anybody here? Any suggestion?"

[Sean de Wolski]

What do you expect as a result? Okay, we do _something_ to the zero elements, I'm not clear on what. Then we do _something_ and magically have a 3-d shape/plot. This is not clear to me. Please explain the two somethings and the expected result.

[Mehdi]

as you can see there are some zero elements at the corners of matrix A. I want to plot matrix A using 'meshc', without plotting zeros. just positive elements.

Answer 1

[Sean de Wolski]

A=[ 0 0 2 0 0; 
  0 1 3 2 0
  3 4 2 1 3
  0 2 3 5 0
  0 0 4 0 0];
A(~A) = nan; %nan out the zeros
meshc(A)

[Mehdi]

Thanks a lot.

This is what I was looking for, exactly. :)

Answer 2

[Mehdi]

Another thing,

Suppose that obtained a matrix like A, using Monte Carlo simulation by running a program so many times. But the final result of A is jagged when we plot it using 'meshc'.

How can we make it smooth?

[Sean de Wolski]

Filter it somehow. Perhaps conv2() would be your friend (you would want to do this before NaNing out the zeros)

[Mehdi]

Thanks for your help. as you know conv2() is a two dimensional convolution. but how to find the other matrix to convolve with A?! I think it is so important. how should we find B in a way that the shape of A doesn't change after convolution?!!

[Mehdi]

I used 'smooth' command and the result was so good.

Thank you anyway