Ultra wide angle lens the difference is only whether distortion is present or not. However, the shorter the focal length, the more difficult it is to implement rectilinear correction. In fisheye lenses, the visual angle is close to or more than 180 degrees in at least one direction. For example, a "diagonal fish eye" would have a viewing angle of at least 180 degrees within the diagonals of the frame. A "circular fisheye" would represent the image in the form of a circle. Rectilinear ultra-wide angle lenses are used in photography and cinematography sometimes to achieve three-dimensional perspective distortion instead of simply two-dimensional barrel
Postmodern mathematics discussions of the philosophy of mathematics and mathematics education and has extensive articles on postmodern mathematics. He introduced the idea of 'fuzzy logic'. This idea rejects the Aristotelian Law of Truth and fallibility of an object (the notion that an object is either true or false). He instead proposed the existence of 'degrees of truth', the idea that an object is characterised into various degrees of truth. Thomas Kuhn (1922-1996) introduced the idea of paradigm shifts in sciences. he asserted that the paradigms and theories in sciences are not fixed but are instead on a continuum and hence are subject