texString display for micrometres missing greek prefix

[duffee]

Variables declared in micrometres are displayed as 'um' where they really should display as 'μm'

loadMacros(
  "PGstandard.pl",
  "parserNumberWithUnits.pl",
);

$thickness = NumberWithUnits( 70, 'um');

Context()->texStrings;
BEGIN_TEXT
The thickness of a human hair is about \($thickness\)
END_TEXT

The rendered text should display as \( 70 \ \rm \mu m\)

I assume that this is also the case for the microNewton, microFarad, microSievert and microMol

[duffee]

In a similar vein, the symbol for ohm is Ω \( \Omega \) which also goes for the kΩ and MΩ. If someone could get degrees to display as ^{\circ}, I'd be a happy camper.

Just getting all my unit display gripes in one place. I realize that if it were easy it would have been done by now :)

similar to #504

[Alex-Jordan]

A difficulty with this is that we store a simple string for each unit. And this string is expected to display in HTML and in PDF hardcopy output, where pdflatex is used. And it is expected to work outside of math mode, and also inside math mode wrapped in \rm{}.

As long as pdflatex is the PDF production tool, I don't think it will be possible to get these symbols without engineering a new way for the display strings to be generated. Even using xelatex, I can get Ω in PDf output, but not μ using the default font.

Or maybe someone else will have better ideas.

[drgrice1]

pdflatex has broad support for Greek letters. \mu m will give 'μm'. So the issue is just in expanding webwork's handling of units to not just store a simple string for the unit name. There should be a TeX string also. Much like the way many other things (functions, constants, operators, etc) are handled in contexts.

[Alex-Jordan]

If I understand what you are saying, yes I do know that in math mode pdflatex has support for Greek letters. But I just tested \mu outside of math mode in a .tex document and it does not work.

This matters because a NumberWithUnits object will often be displayed outside of math mode. So now we are talking about a situaton where if the NumberWithUnits is in math mode, print \mu and if it is not in math mode, print something like \(\mu\) and that is the difficulty I was trying to explain.

[drgrice1]

I see. I thought you probably knew about Greek letters in math mode. I missed that you were talking about getting them outside of math mode.

[Alex-Jordan]

I believe @dpvc wanted to incorporate units into Parser/Value at one point, so they could be controlled by another branch of the Context. (Like you are saying with functions, constants, etc.) But right now units are not truly part of Parser/Value. Hence it would be a significant project.

[dpvc]

if the NumberWithUnits is in math mode, print \mu and if it is not in math mode, print something like (\mu)

Note that there is a TeX macro for testing if you are in math mode (I think it is \ifmmode) that could be used for this. There is also one (\ensuremath?) that will turn on math mode if you aren't in math mode. So perhaps something like {\ensuremath \mu} would do the trick.

Yes, I wanted to add units to the parser, but as Alex says, it is a significant project, and not one that I have ever gotten too.

[Alex-Jordan]

Note that there is a TeX macro for testing if you are in math mode (I think it is \ifmmode) that could be used for this. There is also one (\ensuremath?) that will turn on math mode if you aren't in math mode. So perhaps something like {\ensuremath \mu} would do the trick.

Alas, it seems neither are recognized by MathJax, so that's kind of a whack-a-mole.

The evolution to utf8 support is still happening, and I wonder if a version or two later, WW could have complete support for such characters. Instead of pdflatex, we could use xelatex or luatex. Then μ and Ω could just be dropped as-is. HTML/PDF would not matter, nor would math-mode/not-math-mode.

That's for output. For input, some students will find ways to type in μ and Ω, and when they do, we should recognize them. Other students will just use a plain keyboard, and so for them a plain keyboard version of things like μ and Ω needs to exist too.

Maybe a first step would be to add some structure to Units.pm. For example, to:

                 'um'  => {
                           'factor'    => 1E-6,
                           'm'         => 1
                          },

we could add something like display => 'μm', with display defaulting to the unit's key. And there could be a separate unit:

                 'μm'  => {
                           alias    => 'um',
                          },

Nothing would happen with these until there is development on downstream tools so they can all handle utf8.