Re: Miscellaneous
- To: mathgroup at smc.vnet.net
- Subject: [mg22480] Re: [mg22429] Miscellaneous
- From: "David Park" <djmp at earthlink.net>
- Date: Sat, 4 Mar 2000 02:26:45 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Bob, WRI does seem to update the physical constants. At least I noticed that they changed slightly from Version 3 to Version 4. Perhaps someone at WRI will inform us of their source and how often they are updated. I have written an extension to the Units package called ExtendUnits. There are separate packages for Version 3 and Version 4, but the Version 3 package is falling behind. Among other things the package offers the following features: 1) You can convert to multiple compatible units at once. 2) You can parse to compatible descending units such as Day, Minute, Second. 3) It adds a new output PrefixForm which will automatically select the correct SI prefix. 4) You can specify output format at the same time as conversion. 5) You can convert everything to BaseSI units. 6) You can "deunitize" expressions in a controlled manner so as to obtain expressions with implied input and output units. These can then be used in plotting or numerical work. 7) You can define your own units and use them just like regular Mathematica units. This also allows the definition of synonyms such as GeV for Giga ElectronVolt, or mph for Mile/Hour. 8) A companion package ReducedUnits allows the introduction of unit systems where certain physical constants are set equal to 1. Examples would be geometrized units or atomic units. The packages may be obtained from my web site. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ >Good day to you all, those who know and those that need to know, > > A general question, if you please. > >The Miscellaneous add-on packages contain several very useful >sections viz: ChemicalElements, Resonance AbsorptionLines and >PhysicalConstants and Units. > >I have several questions about this data. > >Where does the data originate ? (some of the values are at odds with >my references) >Are there plans to expand these packages. >Do other Mathematica technical data packages exist, not documented in Mathematica 4. > > I would also like to have addresses of other ( Mathematica or other) data banks, >in material science ( glasses ) and inorganic chemistry. > >Thank you all in anticipation, >Bob Hyde. > >