Computes the distances between pairs of points taken from two different three-dimensional point patterns.

```
# S3 method for pp3
crossdist(X, Y, …, periodic=FALSE, squared=FALSE)
```

X,Y

Point patterns in three dimensions (objects of class `"pp3"`

).

…

Ignored.

periodic

Logical. Specifies whether to apply a periodic edge correction.

squared

Logical. If `squared=TRUE`

, the squared distances are
returned instead (this computation is faster).

A matrix whose `[i,j]`

entry is the distance
from the `i`

-th point in `X`

to the `j`

-th point in `Y`

.

Given two point patterns in three-dimensional space, this function computes the Euclidean distance from each point in the first pattern to each point in the second pattern, and returns a matrix containing these distances.

This is a method for the generic function `crossdist`

for three-dimensional point patterns (objects of class `"pp3"`

).

This function expects two
point patterns `X`

and `Y`

, and returns the matrix
whose `[i,j]`

entry is the distance from `X[i]`

to
`Y[j]`

.

Alternatively if `periodic=TRUE`

, then provided the windows
containing `X`

and `Y`

are identical and are rectangular,
then the distances will be computed in the `periodic'
sense (also known as `torus' distance): opposite edges of the
rectangle are regarded as equivalent.
This is meaningless if the window is not a rectangle.

# NOT RUN { X <- runifpoint3(20) Y <- runifpoint3(30) d <- crossdist(X, Y) d <- crossdist(X, Y, periodic=TRUE) # }