# [NTG-context] Bug in math alignment

Mikael Sundqvist mickep at gmail.com
Wed Nov 2 21:44:04 CET 2022

Hi,

On Wed, Nov 2, 2022 at 9:19 PM Otared Kavian via ntg-context
<ntg-context at ntg.nl> wrote:
>
> Dear Jeong,
>
> Thanks for testing my example, and pointing to the solution using \dm (which I didn’t know…).
> I think the correct behaviour of math alignments should avoid using additional commands such as \dm.
>
> We’ll see what Hans and Mikael say.
>
> Best regards: OK
>
> On 2 Nov 2022, at 12:53, Jeong Dal via ntg-context <ntg-context at ntg.nl> wrote:
>
> Dear Otared,
>
>
> I think there is an issue with the size of math fonts in \frac when used in math alignments, as it is is shown in the following example.
>
>
> I confirm what you said.
>
> However, if I use \dm{} instead of \displaystyle as following, then the output is correct.
>
> \placeformula
> \startformula
> \startalignedcases
> \NC - \Delta u \NC = 0 \NC \qquad\text{in }\, \Omega \NR
> \NC \dm{\frac{\partial u}{\partial {\bi n}}}
> \NC = V u + \phi \NC \qquad\text{on }\, \partial\Omega. \NR
> \stopalignedcases
> \stopformula
> \placeformula
> \startformula
> \startalignedcases
> \NC - \Delta u \NC = 0 \NC \qquad\text{in }\, \Omega \NR
> \NC \dm{\frac{\partial u}{\partial {\bi n}}}
> \NC = V u + \phi \NC \qquad\text{on }\, \partial\Omega. \NR
> \stopalignedcases
> \stopformula
>
> In this example, it is OK to use \dm inside of \startformula … \stopformula.
> I am not sure that it is what Hans and Mikael want.
>
> Thanks,
>
> Best regards,
>
> Dalyoung
>
>

I think in this case it is better to use a mathsimplealign instead of a matrix.

\definemathsimplealign[pdeproblem][
left={\startmathfenced[cases]},
right=\stopmathfenced,
align={1:right,2:left,3:left},
strut=yes,
]

\definemathsimplealign[collected][
left={\startmathfenced[sesac]},
right=\stopmathfenced,
align={1:right,2:left,3:left},
strut=yes,
]

\starttext

\placeformula
\startformula
\startpdeproblem
\NC - \Delta u \NC = 0 \NC \qquad\text{in } \Omega \NR
\NC \frac{\partial u}{\partial {\bi n}} \NC = V u + \phi \NC
\stoppdeproblem
\stopformula

\placeformula
\startformula
\startcollected
\NC - \Delta u \NC = 0 \NC \qquad\text{in } \Omega \NR
\NC \frac{\partial u}{\partial {\bi n}} \NC = V u + \phi \NC