In "u = squeeze(tdata(1,:,:)./10);" the first level of the first dimension of three-dimensional 'tdata' is divided by 10 and converted into a two dimensional matrix. The 'v' is the same for the second level of that first dimension.
In the second pair, the coordinate axes for the point (u,v), (or rather the matrices of points,) is rotated counterclockwise by radian angle 'rlong' and (nu,nv) are the coordinates with respect to these new axes. The third equation gives the euclidean distance of the points from the origin.
In the third pair the first of the pair converts each of those original cartesian coordinates into polar coordinates. The second changes each of the angles in the polar coordinates from radian measure to degree measure. (It would appear the cartesian coordinates here are in reverse order.)
Asking which is the more appropriate is a meaningless question in this context. They all act together as a unified whole.
An alternate interpretation of the second pair is that all the points have been rotated clockwise by radian angle 'rlong' and (nu,nv) are their rotated cartesian coordinates with respect to the original axes.
