(4195835 / 3145727) * 3145727 - 4195835

The image below is a 3d graph of the function x/y in the region of 4195835/3145727. Specifically, the region is:

4195833.0 <= x <= 4195836.4

3145725.7 <= y <= 3145728.4

On a 486/66, the function graphs as a monotonically increasing surface with the low point in the foreground corner (where x is low and y is high) and a high point in the background corner (where x is high and y is low). On a Pentium with the FDIV bug there are two triangular areas in the region where an incorrect result is returned. The correct values all would round to 1.3338 and the incorrect values all would round to 1.3337, an error in the 5th significant digit.

An archive of principal papers on the Pentium FDIV bug is available at: http://www.mathworks.com/company/pentium/index.shtml

A ZIP file containing the Microsoft Excel spreadsheet along with an Encapsulated Postscript copy of this graphic can be retrieved from: http://www.ipsr.unit.ku.edu/stafffil/hoyle/pentium_fdiv/pentgrph.zip

Larry Hoyle (larryhoyle@ku.edu)

Institute for Policy & Social Research

University of Kansas

Nov. 30, 1994