Simplification of units

[barche]

Hi,

Is there a way to simplify units that are the same, for example if I enter:

1J / (1N*m)

The result is:

1.0 m^-1 N^-1 J

I would have expected just 1.0, like when I do 1J / (1J)

This was on 0.5-rc3 using the master branch, is it recommended to use the rewrite branch instead?

[ajkeller34]

Units don't cancel out automatically, apart from powers of the same exact unit including power-of-ten prefixes. This permits expressions like micron/(meter * K), or mV/V, etc.

The rewrite branch will be the basis for the code going forward. A great deal has changed for the better. As you may have gathered from the other Unitful issues, I planned to register and tag Unitful shortly after Julia 0.5 is released. I guess this should happen very soon. However, I'm already nearly done with the revisions and will merge into master within a day or two. At that point the documentation for the rewrite branch will also appear online. I will solicit some community input in between merging and registering the package.

Anyway, to finally answer your question, in the rewrite branch, you will have two options: 1) you can directly convert a dimensionless quantity to a Real or Complex subtype of your choice, or 2) you can use uconvert. Formerly, I had been exploiting convert to do the work of unit conversion, which was ill-advised; now I define uconvert instead. You would use NoUnits as the target unit you want to convert to.

Neither of these options will work if the quantity has dimensions; an error exception is raised. When a quantity x has dimensions, you can access the number in front of the units by dividing out by unit(x), although some caution is warranted doing this sort of thing.

[barche]

Thanks, this makes sense. I also just realized that for some of my work this is desirable, e.g. moist air water content in g/kg.