bug#10554: 24.0.92; No units specified (dimensionless quantities in Emacs Calc)

[Roland Winkler]

On Thu Jan 19 2012 Jay Belanger wrote:
> 
> > In Calc type
> ...
> > Convert this to SI units with u c si RET
> > - That's perfect. We get a dimensionless number.
> ...
> > Now when we type again u c, Calc remembers what we did before.
> > So as a unit it offers "default 1".
> 
> Calc should probably offer "si" as the default in this case.

Yes: If previously one explicitly used "si" as an arg to
calc-convert-units, then it would be reasonable if
calc-convert-units remembered this choice, independent of the actual
SI unit that calc-convert-units obtained at the end of the previous
calculation.

> I'll also change it so that Calc can offer unit systems and composite
> units as default units, but that should probably wait until after 24.1
> comes out.

Agreed. This is nothing urgent.

>From a different perspective, I'd say that "dimensionless" is as
valid a unit as "kg" or "hbar / c". In that sense I'd say that there
should be a possibility to pass this unit "dimensionless" as an arg
to calc-convert-units, similar to any other unit that this function
should use for its final result. I'd say that "1" appears to be a
natural choice in order to express the fact that Calc should obtain
a dimensionless number.

Or is there some other recommended way to do this that I have
overlooked?

Roland