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Drawing Approximate Ellipses When Overflow Interferes With Exact Computation

IP.com Disclosure Number: IPCOM000060377D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08

Publishing Venue

IBM

Related People

Authors:
Makowka, CD [+details]

Abstract

A technique is described whereby the ability to print or display ellipses, from computer computations, is enhanced through an iterative method of arriving at arc parameters for a related ellipse that will approximate the original ellipse. Drawing or displaying part or all of an ellipse using finite precision integer arithmetic produced by a microprocessor is difficult because the quadratic equation describing the ellipse leads to a computer overflow, thereby producing errors during the printing or displaying of the ellipse. The technique described herein provides a reasonable approximation of the ellipse that can be drawn without the errors resulting from an overflow condition.