       Re: Unit conversion of a list of quantities

• To: mathgroup at smc.vnet.net
• Subject: [mg131981] Re: Unit conversion of a list of quantities
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Fri, 8 Nov 2013 16:25:05 -0500 (EST)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• Delivered-to: l-mathgroup@wolfram.com
• Delivered-to: mathgroup-outx@smc.vnet.net
• Delivered-to: mathgroup-newsendx@smc.vnet.net

```On 11/7/13 at 12:28 AM, mariusz.sapinski at gmail.com (mariusz sapinski)
wrote:

>I have the following lists: Edep = {4.9491200000000017`*^-14
>Joules, 1.8669264000000004`*^-14 Joules,
>6.223088000000001`*^-15 Joules}
>mass = {0.043937500000000004` g, 0.06987` g, 0.02329` g}

>I want to calculate dose: dose = Edep/mass

>I get another list (of Quantities):

>{(1.1264*10^-12 Joules)/g, (2.672*10^-13 Joules)/g, (
>2.672*10^-13 Joules)/g}

No you didn't get a list of Quantities. Using your code above,
look at the FullForm of say the first item in you list. You will
get the result:

In:= FullForm[First@dose]

Out//FullForm= Times[1.1264000000000003`*^-12,Power[g,-1],Joules]

Now set up Edep and mass as Quantities as follows:

In:= Edep =
Quantity[#, "Joules"] & /@ {4.9491200000000017`*^-14 ,
1.8669264000000004`*^-14 , 6.223088000000001`*^-15};
mass = Quantity[#, "Grams"] & /@ {0.043937500000000004, 0.06987,
0.02329};

In:= dose = Edep/mass

Out= {1.1264*10^-12 J/g,2.672*10^-13 J/g,2.672*10^-13 J/g}

Now look at the FullForm of the first item

In:= FullForm[First@dose]

Out//FullForm= Quantity[1.1264000000000003`*^-12,Times[Power["Grams",-1],"Joules"]]

Note, it has Head Quantity not Times. So, now you can do

In:= UnitConvert[dose, "Joules"/"Kilograms"]

Out= {1.1264*10^-9 J/kg,2.672*10^-10 J/kg,2.672*10^-10 J/kg}

getting the desired result

```

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