MaplePrimes - answers and comments on Question, Convert units and adopt the new unit in to the value

convert/units

Joe Riel — Wed, 31 Jan 2007 09:50:44 Z

One way is

P := convert(P,units,Torr);

When I tried that, it gave

vanguns — Wed, 31 Jan 2007 10:02:03 Z

When I tried that, it gave me the value of 1 atm in torr, but it still left off the [[torr]] unit; however, I believe I have found the correct way to use units in Maple: Use whichever units you like when assigning values to variables. Maple can do inter-unit calculations just fine, but may display undesired units. Right-click on the value Maple outputs, and convert the units to whatever system you like. This is assuming you are running with(Units).

Thanks for the code snipet

dgiznya — Thu, 08 Feb 2007 21:12:45 Z

Thanks for the code snipet Dave restart: combine( 7*Unit(kg)/(Unit(m)*Unit(s)^2), units ); Units[AddSystem]( NewSI, Units[GetSystem](SI), torr ); Units[UseSystem]( NewSI ); combine( 7*Unit(kg)/(Unit(m)*Unit(s)^2), units ); This will be very useful for me. I need to play around more with customizing units I guess. dgiznya

The System of units may be modified

Dave L — Wed, 31 Jan 2007 11:05:10 Z

I'm glad that the context-menu (right-click) on final results to convert the units works for you. But perhaps you would like to see pressure shown with torrs by default, throughout your computations, without the extra conversion required. This can be done by defining and using a new system of units which is identical to SI except that torr is now the default unit for pressure. Normally, in the SI system, pascals is the default unit for pressure. Consider, restart: combine( 7*Unit(kg)/(Unit(m)*Unit(s)^2), units ); Units[AddSystem]( NewSI, Units[GetSystem](SI), torr ); Units[UseSystem]( NewSI ); combine( 7*Unit(kg)/(Unit(m)*Unit(s)^2), units ); So, after the above, pressure should get expressed with units of torrs. The Units package is very customizable. You can configure it to represent various dimensions in several sorts of useful ways. note: I did not load the Units package above by issuing with(Units); Instead I simply used two individual commands from that package directly. note: In your first post in this thread, you mentioned that when using the right-click context menu on, p := 1*Unit(atm) -> 1*Unit(torr) that p retained the unit atm. That is how context-menus work, by modifying the output. But doing so does not modify the left-hand side of the original assignment. You can verify this by doing, say, p := 1/3 -> 0.3333333333 with the right-click to do Approximate->10 from the context menu. Then query the value of p. It is still the exact rational 1/3, and not the floating-point approximation 0.3333333333. Dave Linder Mathematical Software, Maplesoft.