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Re: A question about Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg34584] Re: [mg34559] A question about Mathematica
  • From: BobHanlon at aol.com
  • Date: Wed, 29 May 2002 02:44:32 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

In a message dated 5/27/02 3:54:14 AM, chenying at ccms.ntu.edu.tw writes:

>   I have a question about Mathematica and yet I couldn't find an answer
>to. Could you please consider giving me a help on this? This is not a
>long question and I hope it won't bother you too much.
>
>   I was doing some computations. A computation gives me something like
>A/A, another computation gives me something like B/B. I then do a
>true-false statement, that is, If [A/A>=B/B, 1, 0]. Since both
>computations (A/A and B/B) equal to one, the statement is true and hence
>the If statement should lend a 1 as specified.
>
>   However, I found out that the If statement lends a zero because
>somehow, in the computations, A/A is less than B/B by the order of 10 to
>the power of -16.
>
>   Some friends told me that it must be because the bytes used by the
>computations A/A and B/B are different, so to correct this problem, I
>should assign the maximum byte to each object.
>
>   Since I am not very familiar with Mathematica, after an afternoon's
>search, I still have no clue about how to do that.
>
>   Could anyone give me a help on this? I really appreciate it.
>

Instead of

If[x >= y, 1, 0]

use

If[Chop[x-y] >= 0, 1, 0]


Bob Hanlon
Chantilly, VA  USA


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