Geoscience Reference
In-Depth Information
Fig. 7.19
Classii cation of separation distances for observations that are equally spaced. h e
lag interval is
h
1, and
h
2,
h
3 etc. are multiples of the lag interval.
D2 = D.*(diag(x*NaN)+1);
lag = mean(min(D2))
lag =
8.0107
Since the estimated variogram values tend to become more erratic with
increasing distances, it is important to place a maximum distance limit
on the calculation. As a rule of thumb, half of the maximum distance is a
suitable limit for variogram analysis. We obtain the half maximum distance
and the maximum number of lags by:
hmd = max(D(:))/2
hmd =
130.1901
max_lags = floor(hmd/lag)
max_lags =
16
h e separation distances are then classii ed and the classical variogram
estimator is calculated:
LAGS = ceil(D/lag);
for i = 1 : max_lags
SEL = (LAGS == i);
DE(i) = mean(mean(D(SEL)));
PN(i) = sum(sum(SEL == 1))/2;
GE(i) = mean(mean(G(SEL)));
end
where
SEL
is the selection matrix dei ned by the lag classes in
LAG
,
DE
is the
