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[1]:= Freq=100*^6 Hertz; Wavelength=SpeedOfLight/Freq Out[1]=(149896229*Meter)/(50000000*Hertz*Second) In[2]:=N[Wavelength] Out[2]=(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[5]:=3 Ohm + 1 Volt/Ampere Out[5] = 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.