# \startcases

There are several built-in commands for displaying mathematical formulas. For instance

\startcases, \stopcases \startmathmatrix, \stopmathmatrix \startalign,\stopalign

Each has its own advantage and can be customized: for a thorough understanding of these commands please refer to Aditya Mohajan's excellent user's guide Using \startalign and friends. These commands can be found in core-mat.tex file, which contains most of the core ConTeXt math macros.

This is an example of aligned equations: \startformula \startcases[align={right,left},distance=3pt] \NC 2x + 3y \NC{} = 10 \NR \NC 3x + 2y \NC{} = 5, \NR \stopcases \stopformula and this is another one: \startformula \startmatrix[align={right,left},distance=3pt,left={\left\{}, right={\right.}] \NC 2x + 3y \NC{} = 10 \NR \NC 3x + 2y \NC{} = 5 \NR \stopmatrix \stopformula

In these structures it is important (well, in the above example it is not important and the result is the same, but I have been told that it is necessary in some other situations...) to notice that the sign "=" is preceded by "\NC{}, since otherwise that sign would be considered as a binary operator and the alignment would be disturbed (at least this is what I guess…Otared K.).

One of the powerful structures in displaying mathematical formulas is the possibility of defining custom maths alignment. For instance the following definition

\definemathmatrix[alignedcases] [align={right,left,left}, distance=3pt, left={\left\{}, right={\right.}, style=\displaystyle]

creates two new commands,

\startalignedcases, \stopalignedcases:

after which one may use them in a displayed formula as follows:

The following formula is displayed in two lines with an appropriate alignment of the equations: \startformula \startalignedcases \NC -\Delta u + g(u) \NC{} = f \NC \quad\mbox{in } \Omega\NR \NC {\partial u \over \partial {\bf n} } \NC{} = h(u) \NC \quad\mbox{on } \partial\Omega \NR \stopalignedcases \stopformula