Boundaries can be found from the mesh using the function 'findBoundaries'. It has the following syntax

boundary = findBoundaries(mesh, querystring, optional arguments);

The return value is a vector. The vector holds the indices of boundaries (a line segment). For example

boundary = findBoundaries(mesh, 'direction', [x1 y1], [x2 y2], width)

returns the boundary elements that are within a distance of width/2 from a line going from [x1 y1] to [x2 y2]

A detailed documentation of the optional arguments and the query strings are given below.

Query string	Description	Arguments	Argument description	Length	Illustration
'arc'	Finds a boundary specified by an arc of the unit circle.	origin	Origin point of the arc	2
		startangle	Starting angle	1
		endangle	Ending angle	1
'direction'	Finds boundaries that fall within a rectangle. The rectangle is defined by a line that starts from origin and goes to waypoint. The line intersects the rectangle in the middle.	origin	Origin point of the rectangle	2
		waypoint	Direction vector of the rectangle	2
		width	Width of the rectangle	1
'inverse'	Inverses the selection	elements	Array that contains the indices of the boundary that is selected	number of elements in the selection
'location'	Finds a boundary nearest to a user specified location	location	The location	number of points specified