Selecting columns with specific elements

I have a 3x2564 matrix with each row specifying the position coordinates of mesh elements of a 3D domain. I need to call the x-coordinate of elements along the free surface/upper face, with z=0. Is there a way to call out columns with the elements of the third row equal to zero? Or do I have to specifically call out each such element once I go through the 'p' matrix developed in the PDE toolbox?

[Shreya George]

Thanks

Answer 1

[KALYAN ACHARJYA]

"Is there a way to call out columns with the elements of the third row equal to zero?"

col_data=find(matrix(3,:)==0)

This col_data gives the column numbers, where 3 rd row elements equal to zero.