Set Covariance of a Window
Computes the set covariance function of a window.
setcov(W, V=W, ...)
W |
A window (object of class |
V |
Optional. Another window. |
... |
Optional arguments passed to |
The set covariance function of a region W in the plane is the function C(v) defined for each vector v as the area of the intersection between W and W+v, where W+v is the set obtained by shifting (translating) W by v.
We may interpret C(v) as the area of the set of all points x in W such that x+v also lies in W.
This command computes a discretised approximation to
the set covariance function of any
plane region W represented as a window object (of class
"owin", see owin.object). The return value is
a pixel image (object of class "im") whose greyscale values
are values of the set covariance function.
The set covariance is computed using the Fast Fourier Transform,
unless W is a rectangle, when an exact formula is used.
If the argument V is present, then setcov(W,V)
computes the set cross-covariance function C(x)
defined for each vector x
as the area of the intersection between W and V+x.
A pixel image (an object of class "im") representing the
set covariance function of W,
or the cross-covariance of W and V.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner r.turner@auckland.ac.nz
w <- owin(c(0,1),c(0,1)) v <- setcov(w) plot(v)
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