First, you need to have the data in Ferret. Do you have a single list
of data, which is rainfall versus time? Once you have that, you can
run the regresst.jnl script. Say your variable is called rain, then
yes? let p = t[gt=rain]
yes? let q = rain
yes? plot rain ! just plot the time series to see what you have
yes? go regresst
! Now, the variables slope, intercep, qhat, and rsquare hold
! the results of the linear fit.
yes? plot/sym q ! this shows the original data as a scatter plot
yes? let myline = p * slop + intercep
yes? plot/vs/over p, qhat ! the linear fit.