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MathGroup Archive 2005

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something like dB

  • To: mathgroup at smc.vnet.net
  • Subject: [mg56516] something like dB
  • From: Zhengji Li <zhengji.li at gmail.com>
  • Date: Thu, 28 Apr 2005 02:40:02 -0400 (EDT)
  • Reply-to: Zhengji Li <zhengji.li at gmail.com>
  • Sender: owner-wri-mathgroup at wolfram.com

Dear Mathematica ers,

    In engineering, we always like values such as power be represented
in dB form.
I can make dB as a Unit, but things go to strange when 0 dB occurs:

    Times[0, dB] will give 0 no matter dB is ReadProtected or not.

    I have tried to define a upvalue for dB: 
     
              dB /: Times[0, dB] = 1; but Mathematica do not allow
this cause dB is not a
"function".

     I can define a new rule for Times: Times[0, dB] = 1, but this may
slow down the
kernel. Anybody know how ?

     Best regards.


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