The input variables to these functions are date (i.e. year), radius (i.e. Z), latitude, and longitude (i.e. X and Y). There's no mention that the components of the returned geomagnetic field vector are X, Y, Z. While this might be an obvious convention, I had no idea and assumed that the order of the components would be the same as the order of the input variables to these functions (i.e. Z, X, Y). I tried to "fix" that with that tiny notation in the parenthesis, but maybe you have a better idea.
As a side note, it might be good to add functions for the magnetic components listed for example here.
The input variables to these functions are date (i.e. year), radius (i.e. Z), latitude, and longitude (i.e. X and Y). There's no mention that the components of the returned geomagnetic field vector are X, Y, Z. While this might be an obvious convention, I had no idea and assumed that the order of the components would be the same as the order of the input variables to these functions (i.e. Z, X, Y). I tried to "fix" that with that tiny notation in the parenthesis, but maybe you have a better idea.
As a side note, it might be good to add functions for the magnetic components listed for example here.