# Documentation

### This is machine translation

Translated by
Mouseover text to see original. Click the button below to return to the English verison of the page.

# convexHull

Class: DelaunayTri

(Not recommended) Convex hull

### Note

`convexHull(DelaunayTri)` is not recommended. Use `convexHull(delaunayTriangulation)` instead.

`DelaunayTri` is not recommended. Use `delaunayTriangulation` instead.

## Syntax

```K = convexHull(DT) [K AV] = convexHull(DT) ```

## Description

`K = convexHull(DT)` returns the indices into the array of points `DT.X` that correspond to the vertices of the convex hull.

`[K AV] = convexHull(DT)` returns the convex hull and the area or volume bounded by the convex hull.

## Input Arguments

 `DT` Delaunay triangulation.

## Output Arguments

 `K` If the points lie in 2-D space, `K` is a column vector of length `numf`. Otherwise `K` is a matrix of size `numf`-by-`ndim`, `numf` being the number of facets in the convex hull, and `ndim` the dimension of the space where the points reside. `AV` The area or volume of the convex hull.

## Examples

### Example 1

Compute the convex hull of a set of random points located within a unit square in 2-D space.

```x = rand(10,1) y = rand(10,1) dt = DelaunayTri(x,y) k = convexHull(dt) plot(dt.X(:,1),dt.X(:,2), '.', 'markersize',10); hold on; plot(dt.X(k,1),dt.X(k,2), 'r'); hold off;```

### Example 2

Compute the convex hull of a set of random points located within a unit cube in 3-D space, and the volume bounded by the convex hull.

```X = rand(25,3) dt = DelaunayTri(X) [ch v] = convexHull(dt) trisurf(ch, dt.X(:,1),dt.X(:,2),dt.X(:,3), 'FaceColor', 'cyan')```

expand all