[Help-gnucap] What is a good way to get joules integrated in a .dat output?

[John Griessen]

I've used the p power probe for a resistor that models a transformer secondary 
winding.

Can I put calculations on the simulation command line?

So far I used a file:

.print tran v(vin) i(C2) v(v2) v(vout) i(R3) i(R2) p(R3) p(R2)
.tran 0 0.000090 .0000005 >voltagedoubler.dat

How would I print the integral of pd(R2) to my waveform file?

When I search joule in http://gnucap.org/dokuwik I find nothing.