Re: Mathematica 9--Is This A Joke?

*To*: mathgroup at smc.vnet.net*Subject*: [mg128866] Re: Mathematica 9--Is This A Joke?*From*: "djmpark" <djmpark at comcast.net>*Date*: Sat, 1 Dec 2012 04:34:10 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <23962465.66692.1354273348752.JavaMail.root@m06>

Kevin, I think the Units package is still there, but just not listed in the Standard Extra Packages. The items that were in PhysicalConstants are now symbols in regular Mathematica. My personal opinion is that it is not very good practice to include units in equations at the first step. It is better to keep all the equations strictly symbolic, do whatever kind of solving or manipulation you have to do, and then at the end substitute values and units to obtain specific answers. David Park djmpark at comcast.net http://home.comcast.net/~djmpark/index.html From: Kevin Wheelock [mailto:jiyajbe at gmail.com] I just installed Mathematica 9. I am horrified. How did this get past QA and Usability Testing? Example: Newton's 2nd Law In Mathematica 8: In[1]:= Needs["Units`"] In[2]:= M := 5 Kilogram In[3]:= a := 10 Meter/Second^2 In[4]:= F := M a; F Out[4]= (50 Kilogram Meter)/Second^2 In[5]:= Convert[%, Newton] Out[5]= 50 Newton In Mathematica 9: In[1]:= M := Quantity[5, "kg"] In[2]:= a := Quantity[10, "m/s^2"] In[3]:= F := M a; F Out[3]= 50kg m/(s)^2 {At this point, Mathematica pops up a dialog offering, among other things, to let me convert this unit. Okay, I enter "N" in the field I was presented} In[4]:= UnitConvert[ Quantity[50, ("Kilograms" "Meters")/("Seconds")^2], "N"] During evaluation of In[4]:= UnitConvert::unkunit: Unable to interpret unit specification N. >> Out[4]= UnitConvert[50kg m/(s)^2,N] {Huh. Okay, I try other things...} In[5]:= UnitConvert[ Quantity[50, ("Kilograms" "Meters")/("Seconds")^2], N] During evaluation of In[5]:= UnitConvert::unkunit: Unable to interpret unit specification N. >> Out[5]= UnitConvert[50kg m/(s)^2,N] In[7]:= UnitConvert[ Quantity[50, ("Kilograms" "Meters")/("Seconds")^2], "Newton"] During evaluation of In[7]:= UnitConvert::unkunit: Unable to interpret unit specification Newton. >> Out[7]= UnitConvert[50kg m/(s)^2,Newton] In[8]:= UnitConvert[ Quantity[50, ("Kilograms" "Meters")/("Seconds")^2], "Newtons"] Out[8]= 50N {Ha! I finally guessed right!} Who the HELL thinks this is better????? "M := Quantity[5,"kg"]"??? Are you KIDDING ME???? Give me back version 8, and QUICKLY!