MathGroup Archive 2005

[Date Index] [Thread Index] [Author Index]

Search the Archive

The question of equality,...

  • To: mathgroup at
  • Subject: [mg60486] The question of equality,...
  • From: terryisnow at
  • Date: Sat, 17 Sep 2005 02:32:32 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

Ok I thought I understood this stuff but maybe not,...

If I wanted to check for bit-for-bit equality of two
arbitrary precision numbers (without regard to how
many of those digits are meaningful) like the way it
would be done using the "==" operator in C, then
neither "==" nor "===" will do the job, is that

For "==" the 5.1 Appendix A says:

"Approximate numbers are considered equal if they
differ in at most their last eight binary digits
(roughly their last two decimal digits)."

For "===" the 5.1 Appendix A says:

"SameQ requires exact correspondence between
expressions, except that it considers Real numbers
equal if their difference is less than the uncertainty
of either of them"

So what can I use then?

Any and all help is much appreciated.


  • Prev by Date: Re: Mathematica: access serial port?
  • Next by Date: Re: Mathematica: access serial port?
  • Previous by thread: Re: 5.2 Install issues
  • Next by thread: Re: The question of equality,...