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Re: something like dB

• To: mathgroup at smc.vnet.net
• Subject: [mg56550] Re: something like dB
• From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
• Date: Fri, 29 Apr 2005 03:19:47 -0400 (EDT)
• Organization: Uni Leipzig
• References: <d4q0rb$o8i$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

HoldForm[0*dB]

??

Regards

  Jens

"Zhengji Li" <zhengji.li at gmail.com> schrieb im 
Newsbeitrag news:d4q0rb$o8i$1 at smc.vnet.net...
> 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.
>