You can follow the formula Hero posted (easy to guess from the voltage-current waveforms), where power is a triangular peak.

You can apply it on the measured waveform (taking the important points only, mainly duration and maximum values), or post the downloaded data, too.

I remember you own a Rigol, for which there should be an already done import function written in Matlab. Then I can calculate the energy dissipated. It would be interesting to compare the results, I expect the approximation Hero wrote will be nearly correct.

When I will have some time (when?) I'd like to make a GUI for power analysis in Matlab, I see it would be an useful thing.