issues with unit package
- To: mathgroup at smc.vnet.net
- Subject: [mg88634] issues with unit package
- From: Jay Ortiz <omaha8master at yahoo.com>
- Date: Sat, 10 May 2008 06:54:10 -0400 (EDT)
Why won't Mathematica when using the Units package eliminate reciprocal units? Consider an example from E&M, finding the wavelength corresponding to a frequency: <<Units` <<PhysicalConstants` In:= Freq=100*^6 Hertz; Wavelength=SpeedOfLight/Freq Out=(149896229*Meter)/(50000000*Hertz*Second) In:=N[Wavelength] Out=(0.299792*Meter)/(Hertz*Second) i.e. Mathematica doesn't know that Meter/(Hertz Second) should reduce to Meter. Shouldn't this be handled? Another example; shouldn't Mathematica reduce expressions in consistent units to a single result? Example: In:=3 Ohm + 1 Volt/Ampere Out = 3 Ohm + 1 Volt/Ampere Why not 4 Ohm, or 4 Volt/Ampere? After all, the documentation entry for Ohm says it's equivalent to Volt / Ampere, so it's reasonable that Mathematica would be aware of that relationship. Doing SI or MKS on those expressions doesn't change anything. Maybe the Units package doesn't extend to manipulating variables with quantities that have units. Am I missing something here? Thanks.