Re: [luatex] this can't happen error with Umiddle (luatex 1.07/texlive 2018)
On 5/17/2018 4:08 PM, David Carlisle wrote:
On 17 May 2018 at 10:36, Hans Hagen wrote:
On 5/16/2018 10:16 AM, David Carlisle wrote:
The following plain tex example
$\left( A \middle| \right)$ %OK
$\Uleft( A \Umiddle class 2 | B \Uright)$ %OK
$\Uleft( A \Umiddle class 2 | \Uright)$ %oops
\bye
produces
! This can't happen (mathspacing).
l.10 $\Uleft( A \Umiddle class 2 | \Uright)$
%oops
! ==> Fatal error occurred, no output PDF file produced!
I'd actually meant to have the A|B but the error message for my typo
seemed a bit harsh!
Having an empty math list to the right of a class 2 \Umiddle might be
odd but shouldn't be an error I assume?
it's a side effect of checking math spacing for noad pairs ... as we default
to zero for (traditionally unknown) combinations anyway, we can make that
check less stringent (so luatex 1.09+ will not abort)
Hans
Thanks. I guessed as much.
Actually that leads to another question which I don't think is quite
clear from the manual.
If you use class 2 (or 3) with any of \Uleft/right/middle at the start
or end of a math list
do they lose their mathbin/mathrel status and become \mathord, as a
classic \mathbin{} does does?
that was indeed the assumption (that these combinations could not happen)
I'm guessing that the issue is that \Umiddle class 2 _doesn't_ lose
its mathbin status at the end of the list
and so put you (or me:-) in the previously impossible situation of a
class 2 atom at the end of the mathlist?
although we tag middle fences in luatex we follow the old approach which
treats it as a left one which then assumes that there is something at
the right of it (which makes sense as why use a middle and not a right
then) and because in luatex we have more spacing combinations we ran
into this special spacing case
Hans
-
Hans Hagen | PRAGMA ADE
Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-
Re: [luatex] this can't happen error with Umiddle (luatex 1.07/texlive 2018)
On 17 May 2018 at 10:36, Hans Hagen wrote:
> On 5/16/2018 10:16 AM, David Carlisle wrote:
>>
>> The following plain tex example
>>
>>
>> $\left( A \middle| \right)$ %OK
>>
>>
>>
>> $\Uleft( A \Umiddle class 2 | B \Uright)$ %OK
>>
>>
>> $\Uleft( A \Umiddle class 2 | \Uright)$ %oops
>>
>> \bye
>>
>> produces
>>
>>
>> ! This can't happen (mathspacing).
>> l.10 $\Uleft( A \Umiddle class 2 | \Uright)$
>> %oops
>> ! ==> Fatal error occurred, no output PDF file produced!
>>
>>
>>
>> I'd actually meant to have the A|B but the error message for my typo
>> seemed a bit harsh!
>>
>> Having an empty math list to the right of a class 2 \Umiddle might be
>> odd but shouldn't be an error I assume?
>
> it's a side effect of checking math spacing for noad pairs ... as we default
> to zero for (traditionally unknown) combinations anyway, we can make that
> check less stringent (so luatex 1.09+ will not abort)
>
> Hans
Thanks. I guessed as much.
Actually that leads to another question which I don't think is quite
clear from the manual.
If you use class 2 (or 3) with any of \Uleft/right/middle at the start
or end of a math list
do they lose their mathbin/mathrel status and become \mathord, as a
classic \mathbin{} does does?
I'm guessing that the issue is that \Umiddle class 2 _doesn't_ lose
its mathbin status at the end of the list
and so put you (or me:-) in the previously impossible situation of a
class 2 atom at the end of the mathlist?
David
David
Re: [luatex] this can't happen error with Umiddle (luatex 1.07/texlive 2018)
On 5/16/2018 10:16 AM, David Carlisle wrote: The following plain tex example $\left( A \middle| \right)$ %OK $\Uleft( A \Umiddle class 2 | B \Uright)$ %OK $\Uleft( A \Umiddle class 2 | \Uright)$ %oops \bye produces ! This can't happen (mathspacing). l.10 $\Uleft( A \Umiddle class 2 | \Uright)$ %oops ! ==> Fatal error occurred, no output PDF file produced! I'd actually meant to have the A|B but the error message for my typo seemed a bit harsh! Having an empty math list to the right of a class 2 \Umiddle might be odd but shouldn't be an error I assume? it's a side effect of checking math spacing for noad pairs ... as we default to zero for (traditionally unknown) combinations anyway, we can make that check less stringent (so luatex 1.09+ will not abort) Hans - Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -
Re: [luatex] this can't happen error with Umiddle (luatex 1.07/texlive 2018)
On Wed, May 16, 2018 at 10:16 AM, David Carlisle wrote: > The following plain tex example > > > $\left( A \middle| \right)$ %OK > > > > $\Uleft( A \Umiddle class 2 | B \Uright)$ %OK > > > $\Uleft( A \Umiddle class 2 | \Uright)$ %oops > > \bye > > produces > > > ! This can't happen (mathspacing). > l.10 $\Uleft( A \Umiddle class 2 | \Uright)$ >%oops > ! ==> Fatal error occurred, no output PDF file produced! > > We are seeing it (at least the "can fix can fix" in the message is fixed) -- luigi
