Geoscience Reference
In-Depth Information
h e value of the mean resultant length decreases with increasing dispersion
(Fig. 10.4). h e dif erence between one and the mean resultant length is
therefore ot en used as a measure of dispersion for directional data,
Movie
10.2
which is the
circular variance
.
h e following example illustrates the use of these parameters by means of
synthetic directional data. We i rst load the data from the i le
directional_1.
txt
and convert all measurement to radians.
clear
data_degrees_1 = load('directional_1.txt');
data_radians_1 = pi*data_degrees_1/180;
We now calculate the resultant vector
R
. Firstly, we compute the
x
and
y
components of the resultant vector.
x_1 = sum(sin(data_radians_1))
y_1 = sum(cos(data_radians_1))
x_1 =
-24.3898
y_1 =
-25.9401
h e mean direction is the inverse tangent of the ratio of
x
and
y
.
mean_radians_1 = atan(x_1/y_1)
mean_degrees_1 = 180*mean_radians_1/pi
Fig. 10.4
h e resultant length
R
of a sample decreases with increasing dispersion of the data
ΚΈ
i
.
