##### Determines if points are on or in the convex hull of a triangulation object

Given a triangulation object `tri.obj`

of \(n\) points in the plane, this
subroutine returns a logical vector indicating if the points
\((x_i,y_i)\)
lay on or in the convex hull of `tri.obj`

.

- Keywords
- spatial

##### Usage

```
on.convex.hull(tri.obj, x, y, eps=1E-16)
in.convex.hull(tri.obj, x, y, eps=1E-16, strict=TRUE)
```

##### Arguments

- tri.obj
object of class

`triSht`

- x
vector of \(x\)-coordinates of points to locate

- y
vector of \(y\)-coordinates of points to locate

- eps
accuracy for checking the condition

- strict
logical, default

`TRUE`

. It indicates if the convex hull is treated as an open (`strict=TRUE`

) or closed (`strict=FALSE`

) set. (applies only to`in.convex.hull`

)

##### Value

Logical vector.

##### See Also

`triSht`

, `print.triSht`

, `plot.triSht`

,
`summary.triSht`

, `triangles`

,
`convex.hull`

.

##### Examples

```
# NOT RUN {
# use a part of the quakes data set:
data(quakes)
quakes.part<-quakes[(quakes[,1]<=-10.78 & quakes[,1]>=-19.4 &
quakes[,2]<=182.29 & quakes[,2]>=165.77),]
q.tri<-tri.mesh(quakes.part$lon, quakes.part$lat, duplicate="remove")
on.convex.hull(q.tri,quakes.part$lon[1:20],quakes.part$lat[1:20])
# Check with part of data set:
# Note that points on the hull (see above) get marked FALSE below:
in.convex.hull(q.tri,quakes.part$lon[1:20],quakes.part$lat[1:20])
# If points both on the hull and in the interior of the hull are meant
# disable strict mode:
in.convex.hull(q.tri,quakes.part$lon[1:20],quakes.part$lat[1:20],strict=FALSE)
# something completely outside:
in.convex.hull(q.tri,c(170,180),c(-20,-10))
# }
```

*Documentation reproduced from package interp, version 1.0-33, License: GPL (>= 2)*

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