I have plotted a graph with xmgrace, the x-values are in linear scale of nm (for wavelength). I want to add a top reciprocal x-axis in eV units.
The formula to transform nm to eV is:
I could not find a way to add another x-axis without adding a new data set.
This is possible without any particular hack which, since we are dealing with xmgrace, is quite amazing :-) Here is how you do it: