[liblouis-liblouisxml] Re: UK maths braille fraction weirdness
- From: "Arend Arends" <mada73bg@xxxxxxxxxx>
- To: <liblouis-liblouisxml@xxxxxxxxxxxxx>
- Date: Mon, 13 Oct 2014 11:42:28 +0200
Paulw.torchtrust signatureMaybe this concerns Marburg as well. I have noticed
that Marburg gives similar output as UK Maths, at least they are much more
similar to each other than Nemeth.
Arend Arends
From: Paul Wood
Sent: Monday, October 13, 2014 11:11 AM
To: liblouis-liblouisxml@xxxxxxxxxxxxx
Subject: [liblouis-liblouisxml] Re: UK maths braille fraction weirdness
As I think we are the main users of the UK tables in liblouis I thought I'd let
you know that we very, very rarely have any Maths in our transcriptions, so I
have no worry about any changes being made. I am no expert on table design and
we have had to make changes to the character definitions in grade 1 to get what
we want and maybe we haven't made the right approach! As we also have our
embossers setup for US computer braille it could be that the original tables
were setup for UK computer braille and this is were we are both getting the
issues. I do know that the literary tables were at the time based on the US
tables as there is evidence of some of the invalid US code being rem'd out.
HTH
Paul
On 13/10/2014 07:54, James Teh wrote:
Hi all,
I am extremely confused by the way some of UK Maths has been implemented in
liblouis*. I'd greatly appreciate it if someone could help clarify. Ultimately,
I want Unicode braille output. This seems to be extremely difficult for UK
Maths because of the way it's implemented.
Let's take a simple fraction which I'll present in LaTeX for brevity:
\frac{a+b}{c}
As I understand it, in UK Maths, the braille should be (using US computer
braille encoding):
<a ;6b>_/c
In ukmaths_edit.ctb, \x0003 (which is defined as the start indicator for a
fraction in ukmaths.sem) is defined as dots 5 6. Similarly, \x0004 (the end
indicator for a fraction) is defined as dots 4 5. As I understand it, they
should be dots 1 2 6 and 3 4 5, respectively.
From what I can see, this has been done because ukmaths_single_cell_defs.cti
defines "<" as dots 5 6 and ">" as dots 4 5. The practical upshot is that if
you use us-table.dis as the first table in mathExprTable for ukmaths.cfg, this
does give you valid US computer braille output. However, as far as I can see,
it's impossible to get valid Unicode braille output.
To make things more confusing, ukmaths_single_cell_defs.cti defines digits as
upper digits with dot 6, so dots 1 2 6 is actually the digit "2" unless defined
earlier (e.g. by us-table.dis).
Why is it implemented this way? Shouldn't how the output is encoded be
determined last, rather than the tables hacking around to get a specific output
encoding? That is, the dots in the tables should all be correct so that any
output encoding can be used, whether it be US computer braille, Unicode braille
or something else. So, \x0003 should be dots 1 2 6 and \x0004 should be dots 3
4 5.
Does anyone actually use these tables currently? Would such a change break
things and why?
Thanks,
Jamie
--
Paul Wood, Chief Technical Officer
Torch Trust
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