For the 'streamline' function to work correctly, the 'x' and 'y' inputs must form a grid of coordinates that specifies the location of each '(u, v)' vector component. However, if the user provides disorganized matrices for 'x' and 'y' that don't form a proper grid and contain duplicate values, it can lead to issues.
The grid values for 'x' and 'y' don't need to be uniformly spaced, but they must be monotonic. This means they should either increase or decrease consistently along one dimension while remaining constant along the other, similar to the requirements for 'contour()' function inputs. The 'meshgrid()' function can be useful for generating these matrices correctly.
The same information can be found here:
I hope this helps.
