Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.soft-sys.math.maple > #317

Re: Units conversion

Show all headers | View raw

You can define and use a modified version of the SI system in which volts/meter is the default for expressing items with the same dimensions as of kg*m/s^3*A.

(This is typeset in ascii, but of course the units get printed more nicely with the double [[]] brackets in the GUI.)

restart;

with(ScientificConstants):

E := 30*10^(-15)*Unit('T')*GetValue(Constant(c))*Unit('m')/Unit('s'); 

          449688687 Units:-Unit('T') Units:-Unit('m')
          -------------------------------------------
                50000000000000 Units:-Unit('s')     
 
combine(E,units);

              449688687               /('kg') ('m')\
            -------------- Units:-Unit|------------|
            50000000000000            |     3      |
                                      \('s')  ('A')/

convert(combine(E,units),units,volts/meter);

                  449688687               /'V'\
                -------------- Units:-Unit|---|
                50000000000000            \'m'/

simplify(%); # back to where we started, as it is not special to SI

              449688687               /('kg') ('m')\
            -------------- Units:-Unit|------------|
            50000000000000            |     3      |
                                      \('s')  ('A')/

# define a new version of SI
Units:-AddSystem(newSI,Units:-GetSystem(SI),volts/meter);
Units:-UseSystem(newSI);

combine(E,units); # now done in one step (and `simplify` does not undo it)

                  449688687               /'V'\
                -------------- Units:-Unit|---|
                50000000000000            \'m'/


That should also play reasonably nicely with more automatic simplification of units with arithmetic that one gets after loading Unit:-Standard.

best,
acer

Back to comp.soft-sys.math.maple | Previous | Next — Previous in thread | Find similar | Unroll thread

Thread

Units conversion Thomas Dean <tomdean@speakeasy.org> - 2012-01-17 22:12 -0800
  Re: Units conversion acer <maple@rogers.com> - 2012-01-18 06:03 -0800

csiph-web