DEFECTIVE PENTIUM FPU'S

[<lrbu00[ AT ]xd88.kodak.com>]

 NETTERS: BEWARE OF FPU ERROR IN INTEL 60 AND 90 MHZ PENTIUM CHIPS:
 THE FOLLOWING EXPRESSION GIVES A GRIEVOUSLY INCORRECT ANSWER:
 Z=X-(X/Y)*Y = 256,  FOR X=4195835 AND Y=3145727.
 OBVIOUSLY THE CORRECT ANSWER IS EXACTLY 0, WITHIN ROUND-OFF ERROR.
 NOW WHAT? COMPUTE STATISTICAL PROBABILITIES OF ERRORS IN COMPUTED RESULTS?
 INTEL HAS JUST TOLD ME ON THE PHONE THEY DO NOT CONSIDER THIS A PROBLEM. THEY
 SAY THEY HAVE KNOWN ABOUT IT SINCE LAST JUNE.
 REGARDS
 --
 John M. McKelvey			email: mckelvey[ AT ]Kodak.COM
 Computational Science Laboratory	phone: (716) 477-3335
 2nd Floor, Bldg 83, RL
 Eastman Kodak Company
 Rochester, NY 14650-2216
 --