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Re: Incompatible units?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg97901] Re: Incompatible units?
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Wed, 25 Mar 2009 05:43:22 -0500 (EST)
  • References: <gpt6i8$qr7$1@smc.vnet.net> <gpvhb8$gt5$1@smc.vnet.net>

On Mar 24, 12:27 pm, Mathias Lindner <mathias.lind... at web.de> wrote:
> I use Convert very often and it's annoying. As an example: The result of
> the multiplication of a frequency and a time has to be dimensionless.
> Anyway, the shown result is always in Hertz Second. Only with
> Convert[...,1] the units are avoided. The same applies for Watt/(Volt
> Amp), Kilo/Milli etc.
> Any idea what goes wrong here?

The problem may lie in the fact that units that may have the same
dimensions sometimes should not be equated. Take, for instance, the
Newton Meter (N m), which occurs in moment of force expressions. It is
dimensional equivalent to a Joule. Nevertheless, in many cases you
wouldn't like the N m to be simplified to J.

BTW I actually never use units in calculations. As long as you keep
track of what the numbers mean there's never a problem.

Cheers -- Sjoerd


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