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Re: Terrible unit trouble in Mathematic 9

• To: mathgroup at smc.vnet.net
• Subject: [mg129163] Re: Terrible unit trouble in Mathematic 9
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Wed, 19 Dec 2012 04:56:15 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-newout@smc.vnet.net
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On 12/18/12 at 2:39 AM, tio540s1 at gmail.com wrote:

>I continue to receive "Unable to interpret unit specification m/s"
>(for example, but almost anything I attempt returns this message)
>with input: UnitConvert[55 mi/h,"m/s"] or UnitConvert[55 mi/h,m/s]
>or any other combination of quotes, omitted quotes, etc. Even the
>prediction/suggestion box, when I execute Quantity[55,"mi/hour"},
>after it returns 55 mi/h, if I type in any combination of m/s,
>"m"/"s", "m/s", etc. into the box that opens when I select "Convert"
>in the prediction box yields the same "unable to interpret unit
>specification.

>What the heck????

Try

In[1]:= speed = Quantity[55, "Miles/Hour"]

Out[1]= 55mi/h

In[2]:= UnitConvert[speed] // N

Out[2]= 24.5872m/s

Mathematica ver 9 seems to strongly prefer plural for units. And
there is no need to specify target units when converting to
standard metric units.

Noting

In[3]:= FullForm[%]

Out[3]//FullForm= Quantity[24.58724917449835`,Times["Meters",Power["Secon=
ds",-1]]]

it should not be surprising that

In[4]:= UnitConvert[speed, "Meters"/"Seconds"] // N

Out[4]= 24.5872m/s

works.