Accuracy for relativistic motion.


Relativistic equations of motion are always automatically used, when necessary.

For the technique used see the note on integrating relativistic equations of motion.


When the motion is relativistic the equations of motion are solved to an inaccuracy slightly better than that corresponding to the 'ray fractional inaccuracy' that has been entered. The relativistic correction to the mass is always used. For example, corrections for the rate of change of mass with time are used above the following threshold energies for electrons:

inaccuracy level

threshold energy


25.6 eV


256 eV


2.57 keV


27.6 keV

(but these thresholds are raised if the magnetic force starts to exceed the electric force, becoming unnecessary for a pure magnetic field).


For a ray tracing inaccuracy level of 0.000001, which would very rarely (if ever) be justifiable, even a 0.5eV electron would be treated by the program as relativistic!

For examples of accurate relativistic motion see for example test2d05, test3d04 and test3d05.


Return to general note on accuracy of ray tracing.