>>
APLDN Home

>>
Events

>>
Trainings

>>
APL Books

>>
APLDN Links

>>
Discussion Groups

>>
Downloads

>>
Articles

>>
Library

>>
Learning Tools

>>
APLDN User IO

>>
APL2000.com




Bug Reports

Author Thread: Arithmetic Bug ( Interpreter or Pentium III ? )
Alain.AMIOUNI
Arithmetic Bug ( Interpreter or Pentium III ? )
Posted: Friday, May 27, 2005 9:01 AM (EST)


      © Either my Pentium III is bugged or there is a problem...elsewhere.
      © Precision of double floating-point format (non-extended)
      © is 53 bits, including the implicit leading 1 bit of the
      © significand. So, there should be no glitch as early as
      © at 2*44, accuracy being guaranteed up to ¯1+2*53.
      © Numeric encoding of floating-point data type is correct
      © but comparison functions are seemingly flawed:
     

      (2*44)=1+2*44
  1
      (2*44)=2+2*44
  0
      (2*45)=1+2*45
  1
      (2*45)=2+2*45
  1
      (2*45)=3+2*45
  1
      (2*45)=4+2*45
  0


Comments:

Author Thread:
William.Rutiser
Arithmetic Bug ( Interpreter or Pentium III ? )
Posted: Friday, May 27, 2005 9:11 AM (EST)
Look up "comparison tolerance" in your APL documentation. Set the system variable QUAD-CT to zero, then repeat your experiments.

     

Alain.AMIOUNI
Arithmetic Bug ( Interpreter or Pentium III ? )
Posted: Friday, May 27, 2005 9:22 AM (EST)

I stupidly overlooked this obvious point.

My pseudo-notification will have been helpful

in only one respect: recalling to take CT into account

before doing numerics !

Sorry...

     



APL2000 Official Web Site

Not all who wander are lost.
-- Tolkien

APLDN Home   |    |  Events   |  Trainings   |  APL Books   |  APLDN Links   |    |  Discussion Groups   |    |  Downloads   |  Articles   |  Library   |  Learning Tools   |  APLDN User IO   |  APL2000.com   |