# Changes

,  07:47, 29 November 2020
Created page with "In order to type matrices in math formulas, there is the command {{cmd|definemathmatrix}}. Once a certain type of matrix is defined, one can also add a simple command in order..."
In order to type matrices in math formulas, there is the command {{cmd|definemathmatrix}}. Once a certain type of matrix is defined, one can also add a simple command in order to type matrices in a Matlab or Scilab format.

Here are a few examples

<context source = yes>
%% defining matrix with parentheses
\definemathmatrix[pmatrix]
[matrix:parentheses]
[simplecommand=pmatrix]

%% defining matrix with brackets
\definemathmatrix[bmatrix]
[matrix:brackets]
[simplecommand=bmatrix]

%% defining determinant with bars
\definemathmatrix[determinant]
[matrix:bars]
[simplecommand=thedeterminant]
\starttext
Let $A$ be the matrix
\startformula
A :=
\startpmatrix
\NC 2 \NC 3 \NR
\NC 1 \NC 2 \NR
\stoppmatrix.
\stopformula
Show that
\startformula
{\rm det}(A) = \startdeterminant
\NC 2 \NC 3 \NR
\NC 1 \NC 2 \NR
\stopdeterminant = 1.
\stopformula
Compute the matrix $AB$ where $B$ is the matrix
\startformula
B := \pmatrix{2, -3 ; -1, 2}.
\stopformula
\stoptext
</context>
It is possible to have different delimiters on the left and on the right. For instance:
<context source = yes >
\definemathmatrix[pvmatrix]
[left={\left(\thinspace},
right={\thinspace\right|}]

\definemathmatrix[rpmatrix]
[left={\left.\thinspace},
right={\thinspace\right)}]

\starttext
\startformula
\startpvmatrix
\NC 11 \NC 12 \NC 13 \NR
\NC 21 \NC 22 \NC 23 \NR
\NC 31 \NC 32 \NC 33 \NR
\stoppvmatrix
\startrpmatrix
\NC 0 \NR
\NC 1 \NR
\NC 2 \NR
\stoprpmatrix
\stopformula

\stoptext
</context>

In ConTeXt LMTX beginning version 2020-11-27, it is possible to create « block » matrices where the blocks are separated by vertical or horizontal lines (respectively {{cmd|VL}} and {{cmd|HL}}). For instance the above example can be typeset more easily by the following (the output may be incorrect on this wiki: if this is the case copy the code below and typeset it on your machine with ConTeXt LMTX):

<context source = yes>
\definemathmatrix[mymatrix]
[left={\left\lparent\thinspace}, % instead of the left parenthesis, one can use any other fence
right={\thinspace\right\rparent}] % instead of the right parenthesis, one can use any other fence

\starttext
Here is $3 \times 3$ matrix with a column added to it
\startformula
\startmymatrix
\NC 11 \NC 12 \NC 13 \VL 0 \NR
\NC 21 \NC 22 \NC 23 \VL 1 \NR
\NC 31 \NC 32 \NC 33 \VL 2 \NR
\stopmymatrix
\stopformula
Here is block matrix:
\startformula
\startmymatrix
\NC A \VL B \NR
\HL
\NC C \VL D \NR
\stopmymatrix
\stopformula
and here is another one
\startformula
\startmymatrix
\NC A \VL[3,green] B \NR %
\HL[10,red]
\NC C \VL D \NR
\stopmymatrix
\stopformula

\stoptext
</context>
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