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[UDUNITS #MZJ-180852]: udunits question molecules/cm^2
- Subject: [UDUNITS #MZJ-180852]: udunits question molecules/cm^2
- Date: Wed, 11 May 2011 15:49:34 -0600
James,
> If I have a variable and the units are molecules/cm^2 is it acceptable to
> enter the units as molecules/cm2, that seems to be what comment 2. says below.
> But running udunits2 with molecules/cm2 says 'Don't recognize "molecule/cm2"'.
> Entering just cm-2 for units seems a bit vague and non-specific compared to
> molecules/cm2.
>
>
> <unit>
> <!--
>
> 1. The mole is the amount of substance of a system which contains
> as many elementary entities as there are atoms in 0.012 kilogram of
> carbon 12.
>
> 2. When the mole is used, the elementary entities must be specified
> and may be atoms, molecules, ions, electrons, other particles, or
> specified groups of such particles.
>
> -->
> <base/>
> <name>
> <singular>mole</singular>
> </name>
> <symbol>mol</symbol>
> </unit>
> <unit>
You should use the unit "1/cm2".
The UDUNITS package won't understand the unit "molecule/cm2".
Attaching additional meaning to a unit string (e.g., "molecule") is considered
bad form. See section 7.4 at <http://physics.nist.gov/Pubs/SP811/sec07.html>.
The proper place to put such information is in the name of the physical
quantity.
> ------------------------------------------------------------------------------
> | James E. Johnson | address: |
> | Wyle Information Systems, Inc. | NASA Goddard Space Flight Center |
> | e-mail: address@hidden | Distributed Active Archive Center |
> | phone: 301-614-5121 | Code 610.2, Bldg 32, Room S130G |
> | fax: 301-614-5268 | Greenbelt, MD 20771 |
> ------------------------------------------------------------------------------
Regards,
Steve Emmerson
Ticket Details
===================
Ticket ID: MZJ-180852
Department: Support UDUNITS
Priority: Normal
Status: Closed