Graham's scan is a method of finding the convex hull of a finite set of points in the plane with time complexity O(n log n). It is named after Ronald Graham, who published the original algorithm in 1972. The algorithm finds all vertices of the convex hull ordered along its boundary.

A convex polygon is defined as a polygon with all its interior angles less than 180°. This means that all the vertices of the polygon will point outwards, away from the interior of the shape.

The Graham’s Scan Geometry App provides for a touch-enabled point entry workspace with X and Y axes. Point entry is permitted everywhere on the workspace with a minimum of 4 points and a maximum of 12 points entered.

After the point entry and computation the Graham’s Scan Convex Hull Polygon is displayed.

A Data Table displays the (x,y) coordinates of the entered points.