This knot was done using Ferguson Patches which is a form of Bicubic Surface. The concept behind Bicubic patches is that in order to build a smooth representation of an object such as the one above we do not need to store thousands of small polygons to draw the object. Instead we store a very coarse mesh of points which lie on the surface and interpolate along them to find as many interior points (new point which lie between two original points) as we want. We can then draw the object forming again polygons or using lines. The most common form of interpolation Bicubic interpolation, and in 3D there are various methods to interpolate between 4 points to find any interior point and form a patch, some are Hermite Patches, Bezier Patches, B-Spline Patches and Ferguson Patches.
This programm draws this knot and rotates it using 2 methods of Bicubic patch interpolation.