evaln(x1, y1, x2, y2)

evaluates the noise level as well as the overall offset of the data,
over a area of the data. The results are stored in the NOISE and
SHIFT contexts This command is called automatically whenever a data
set is read. The command will prompt for the last selected region
with the POINT command

see also : shift noise

NPK Documentation, version 0.995 - 2009-10-14