# isConnected

Test if two vertices are connected by an edge

## Syntax

``TF = isConnected(TR,startID,endID)``
``TF = isConnected(TR,E)``

## Description

example

````TF = isConnected(TR,startID,endID)` returns a `logical` column vector whose elements are 1 (`true`) when the specified starting and ending pairs of vertices are connected by an edge. `startID` and `endID` specify edges by their starting and ending points, where each point is represented by its row number in `TR.Points`. The return value `ID` identifies triangles by their identification numbers.```

example

````TF = isConnected(TR,E)` specifies the edge start and end vertex IDs in a two-column matrix `E`.```

## Examples

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```load trimesh2d TR = triangulation(tri,x,y);```

Determine whether vertices `3` and `117` are connected by an edge.

`TF = isConnected(TR,3,117)`
```TF = logical 1 ```

Determine whether vertices `3` and `164` are connected by an edge.

`TF = isConnected(TR,3,164)`
```TF = logical 0 ```

Create a 3-D Delaunay triangulation.

```rng default; X = rand([10,3]); DT = delaunayTriangulation(X);```

Determine whether vertices `2` and `7` are connected by an edge, and whether vertices 4 and 9 are connected.

```E = [2 7; 4 9]; TF = isConnected(DT,E)```
```TF = 2x1 logical array 0 1 ```

## Input Arguments

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Triangulation representation, specified as a scalar `triangulation` or `delaunayTriangulation` object.

Data Types: `triangulation` | `delaunayTriangulation`

Starting vertex identification for each edge, specified as a column vector. A vertex identification number is the number of the row in the `Points` property that corresponds to the vertex.

Data Types: `double`

Ending vertex identification for each edge, specified as a column vector. A vertex identification number is the number of the row in the `Points` property that corresponds to the vertex.

Data Types: `double`

Edge matrix, specified as a two-column matrix. Each row contains the starting and ending vertex identifications for an edge. A vertex identification number is the number of the row in the `Points` property that corresponds to the vertex.

Data Types: `double`

## Version History

Introduced in R2013a