Styjun

I wish to write the following block matrix in LaTex.

I have been trying a bunch of stuff, but none of it seems to work. In particular, I tried the following:

beginbmatrix
0 & -1& & & & & 0 & & & &\
1 & 0 & & & & & & & & &\
 & & cdot & & & & & & & &\
 & & & cdot & & & & & & &\
 & & & & cdot & & & & & &\
 & & & & & 0 & 1 & & & &\
 & & & & &-1 & 0 & & & &\
 & & & & & & & cdot & & &\
 & & & & & & & & cdot & & \ 
 & & & & & & & & & cdot & \
0 & & & & & & & & & & 0\ 
endbmatrix

But this is pretty ugly and so any suggestions will be much appreciated.

Perhaps

$left(beginarraycccccc
left[beginarraycc
0 & 1\
-1 & 0
endarrayright] & & & & & 0\
 & ddots\
 & & left[beginarraycc
0 & 1\
-1 & 0
endarrayright]\
 & & & 0\
 & & & & ddots\
0 & & & & & 0
endarrayright)$ 

Just for the fun of it! :-)

documentclassarticle
usepackageamsmath,array

begindocument

[
beginpmatrix
newcommandlr[1]multicolumn1c#1
newcommandrr[1]multicolumn1c#1
;
beginarray@*10c@
cline1-2
lr0 & rr1 &&&&&&&& raisebox-1em[0pt][0pt]$0$\
lr-1 & rr0 \
cline1-2
&& ddots \
cline4-5
&&& lr0 & rr1 \
&&& lr-1 & rr0 \
cline4-5
&&&&& 0 \[-1ex]
&&&&&& ddots \
&&&&&&& 0 \[-1ex]
&&&&&&&& ddots \
multicolumn2c0 &&&&&&&& 0
endarray
;;
endpmatrix
]

enddocument

Here there is my proposal as the original picture using bmatx command that replace a boxed matrix.

documentclassarticle
usepackagemathtools
newcommandbmatxboxedbeginmatrix 0& 1 \ -1& 0endmatrix

begindocument
[
beginpmatrix
, bmatx& & & & & & & 0 \ 
 & ddots& & & & \ 
 & & bmatx & & & & \ 
 & & & ddots& & &\ 
 & & & & 0 & &\ 
 & & & & & & ddots\ 
0 & & & & & & & 0 
endpmatrix
]

enddocument

The best code is provided thanks to the precious comment of @Bernard.

Here's another solution. It uses a pmatrix environment for the overall matrix and a custom macro called blockmat for the 2x2 inner matrices.

documentclassarticle
usepackagearray,amsmath
newcommandblockmat%
 beginarray
 hline 0 & 1^mathstrut \ -1 & 0 \ hline
 endarray
begindocument
[
beginpmatrix
blockmat & & & & & 0 \
 & ddots & & & & \
 & & blockmat & & & \
 & & & 0 & & \
 & & & & ddots & \
0 & & & & & 0 \ 
endpmatrix
]
enddocument

Here's a solution using TikZ that will work in all kinds of context, not just matrices, to draw boxes. You just need to put tl in the point where the top-right corner is supposed to be and br where the bottom-right will be. You can also use any TikZ feature to modify your box. Obviously this needs to be fine tuned depending on what exactly you're using it for (spacing etc.).

newcountertextbox
deftlstepcountertextboxtikzmarknodeathetextboxstrut
defbrtikzmarknodebthetextboxstrutbegintikzpicture[overlay, remember picture]draw (athetextbox.north west) rectangle (bthetextbox.south east);endtikzpicture

The spacing in this version is not optimized for matrices, but you can use

tikzmarknodebthetextboxstrutbegintikzpicture[overlay, remember picture]draw ($(athetextbox.north west)+(-0.4arraycolsep,0ex)$) rectangle ($(bthetextbox.south east)+(0.4arraycolsep,0ex)$);endtikzpicture

to add extra space.

Full code:

documentclassarticle
usepackagetikz
usepackageamsmath 
usetikzlibrarytikzmark,calc
newcountertextbox
deftlstepcountertextboxtikzmarknodeathetextboxstrut
defbrtikzmarknodebthetextboxstrutbegintikzpicture[overlay, remember picture]draw (athetextbox.north west) rectangle (bthetextbox.south east);endtikzpicture
begindocument
[
beginbmatrix
tl0 &-1 & & & & & & & & 0 \
1 & 0br & & & & & & & & \
 & & cdot & & & & & & & \
 & & & cdot & & & & & & \
 & & & & cdot & & & & & \
 & & & & &tl0 & 1 & & & \
 & & & & &-1 & 0br & & & \
 & & & & & & & cdot & & \
 & & & & & & & & cdot & \ 
0 & & & & & & & & & cdot \
endbmatrix
]
enddocument