Question: Questions from a simple calculation with units.


I am new to Maple and doing a trivial calculation raised a few questions. I tried to calculate the average density of a wire with the following specs: 

  • diameter = .40 inches
  • length = 1000 feet
  • weight = 61 pounds

Here's what I have come up with. 

wirevolume:=(wirediameter/2)2 * Pi * wirelength:= 

I get a result of: (3517.654557[kg/m3])/π. I then had to (Rt Click | Approximate | 5) and Replace units] from kg/mto g/cm3

Going through this process left me with a few questions:

  1. Can I get Maple to approximate π to a few decimal places automatically or will any calculation involving π give me a result with the letter? Should I just use 3.1415 instead? For the purposes of this calculation, four decimal places is more than sufficient. To be honest, throwing the spool of wire into a pool would really give me the information I need :)
  2. Can I get Maple to give me results in specific units without the need to (Rt Click | Units | Replace Units)? I tried to specify wiredensity[g/cm3] but that didn't give me the results I wanted.
  3. Can I "preload" the Units package (is that the right term?) so that I don't have to manually call it every time I want to use units?


Many thanks,



> with(Units[Standard]); > wirediameter := Units[Natural][`*`](.40, Unit('inch')); > wirelength := Units[Natural][`*`](1000, Unit('ft')); > wirevolume := Units[Natural][`*`](Units[Natural][`*`](Units[Natural][`^`](Units[Natural][`*`](wirediameter, Units[Natural][`/`](2)), 2), Pi), wirelength); print(??); # input placeholder print(??); # input placeholder  > wireweight := Units[Natural][`*`](61, Unit('lb')); > wiredensity := Units[Natural][`*`](wireweight, Units[Natural][`/`](wirevolume));

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