# pairdist.pp3

##### Pairwise distances in Three Dimensions

Computes the matrix of distances between all pairs of points in a three-dimensional point pattern.

##### Usage

```
## S3 method for class 'pp3':
pairdist(X, \dots, periodic=FALSE, squared=FALSE)
```

##### Arguments

- X
- A point pattern (object 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

This is a method for the generic function `pairdist`

.

Given a three-dimensional point pattern `X`

(an object of class `"pp3"`

),
this function computes the Euclidean distances between all pairs of
points in `X`

, and returns the matrix of distances.

Alternatively if `periodic=TRUE`

and the window containing `X`

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

If `squared=TRUE`

then the *squared* Euclidean distances
$d^2$ are returned, instead of the Euclidean distances $d$.
The squared distances are faster to calculate, and are sufficient for
many purposes (such as finding the nearest neighbour of a point).

##### Value

- A square matrix whose
`[i,j]`

entry is the distance between the points numbered`i`

and`j`

.

##### See Also

##### Examples

```
X <- runifpoint3(20)
d <- pairdist(X)
d <- pairdist(X, periodic=TRUE)
d <- pairdist(X, squared=TRUE)
```

*Documentation reproduced from package spatstat, version 1.18-4, License: GPL (>= 2)*