RE: Units

*To*: mathgroup at smc.vnet.net*Subject*: [mg32424] RE: [mg32414] Units*From*: "David Park" <djmp at earthlink.net>*Date*: Sat, 19 Jan 2002 19:03:21 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

Juan, I am not quite certain what you mean by "automatically converted". In any case, I have a pair of packages at my web site called V4ExtendUnits and V4ReducedUnits which significantly extends and simplifies the standard Units package. There is also a tutorial. ReducedUnits allows you to define unit systems in which some of the physical constants are set equal to 1. This allows you to implement, for example, atomic units, which may be what you are looking for, or geometrical units. ExtendUnits has a routine that allows you to deunitize an expression so that the input and output variables have specified implied units. This is useful in doing numerical and graphical work. There are even routines that allow you to install your own units and use them just like the Mathematica supplied units. So, you could, for example, use KeV instead of Kilo ElectronVolt. One rule that I find useful when working with units is: Don't put explicit units in the equations. Put the units in the data. Solve the equations and then substitute the data with the explicit units. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: Juan Fuentes [mailto:jfuentes at ff.oc.uh.cu] To: mathgroup at smc.vnet.net > > Dear colleagues: > Could any one say me about a package to work in solving > physics problems in the area of semiconductor physics where the units are > authomatically converted? Thanking in adavance, Juan > >