What about the dependence on the size of the time slice?
It is unclear what the unit fo the frequency. Hz? ot logHz (which should be expressed as 10^1, 10^2, ...)?
Can you combine the result of the caluculation and the error together?
i.e. Combine the plot similar to http://nodus.ligo.caltech.edu:8080/COMSOL/4 and your plot with the horizontal axies lined up.