Re: Wolfram | Alpha: Acres per square mile? (oddities)

*To*: mathgroup at smc.vnet.net*Subject*: [mg101185] Re: [mg101146] Wolfram | Alpha: Acres per square mile? (oddities)*From*: "David Park" <djmpark at comcast.net>*Date*: Fri, 26 Jun 2009 06:50:07 -0400 (EDT)*References*: <11817264.1245931862049.JavaMail.root@n11>

As for units, you can easily install your own convenience units with the ExtendUnits package. Needs["Units6`ExtendUnits6`"] InstallNewUnit[SquareMile -> Mile^2] InstallNewUnit[SquareMeter -> Meter^2] InstallNewUnit[Kilometer -> Kilo Meter] Acre/SquareMile // ToUnit[{Acre/Kilometer^2, Acre/Hectare, Hectare/SquareMile, SquareMeter/Acre, Hectare/Kilometer^2, SquareMile/SquareMeter, 1}] {0.386102 Acre/Kilometer^2, 0.00386102 Acre/Hectare, 0.404686 Hectare/SquareMile, 6.32321 SquareMeter/Acre, 0.15625 Hectare/Kilometer^2, 6.03285*10^-10 SquareMile/SquareMeter, 0.0015625} As for W|A, lately I am more impressed. A couple of days ago I tried to calculate the cooking time for a roast and got 113 arc minutes, which was then converted to radians and grads. But today, when I used " 4.53 pounds at 26 minutes per pound " I obtained a correct answer. And if I enter " 14:25:00 GMT " it gives my corresponding local time because it knows roughly where I am. (But just now it gave me a stock chart that didn't even have the same symbol and I had to choose to switch to a calendar unit.) And if you type "Sunset" it will give you your local time of sunset. I'm more impressed. David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: AES [mailto:siegman at stanford.edu] Just out of curiosity (and a current need for info) (and to start learning about W|A), typed: Acres per square mile into Wolfram | Alpha. Results came back (had to do a little hand editing of the following): Assuming U.S. acres for "acres" Use international acres commercial acres Irish acres Hungarian acres instead Input interpretation: acres/mi^2 Unit conversions: 0.3861 acres per square kilometer 6.323 square meters per acre 0.1563 hectares per square kilometer 0.4047 hectares per square mile 0.003861 acres per hectare Don't see "640" there anywhere! -- and something seriously wrong with that first unit conversion? (not to mention all the others) -- or at least the way it's phrased -- more like 250 acres per square kilometer? Went to M7, tried Needs["Units`"] Convert[Acre, Mile^2] Mile^2/640 Went to Units Tutorial: Seems odd to see "Centimeter", "Meter", "Micron", "Mile", and a bunch of arcane units listed there -- but NOT "Kilometer"??? ("Gram" and "Kilogram" are in there).