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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).




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