# crossdist.pp3

##### Pairwise distances between two different three-dimensional point patterns

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

##### Usage

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

##### Arguments

- 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).

##### Details

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.

##### Value

A matrix whose `[i,j]`

entry is the distance
from the `i`

-th point in `X`

to the `j`

-th point in `Y`

.

##### See Also

##### Examples

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

*Documentation reproduced from package spatstat, version 1.61-0, License: GPL (>= 2)*