[ns] how can I turn off the energy trace?

[jianli guo]

 I dont want the following lines in my trace file

N -t 11.236267 -n 59 -e 9999.600820
N -t 11.236267 -n 29 -e 9999.600820
N -t 11.236267 -n 10 -e 9999.600820
N -t 11.236267 -n 92 -e 9999.600820
N -t 11.236267 -n 21 -e 9999.600820
N -t 11.236267 -n 8 -e 9999.600820
N -t 11.236267 -n 38 -e 9999.600820
N -t 11.236267 -n 85 -e 9999.600820


charlie