Xjyuk

I was writing an upper triangular matrix but due to large entry was unable to get in a good view.

documentclass[10pt,a4paper]article
usepackage[utf8]inputenc
usepackageamsmath,mathtools
usepackageamsfonts
usepackageamssymb
begindocument
 $$ J(hatPhi)(p)=
 beginpmatrix*[c]
 ((hatPhi(p)_ij))_i,j=1^r &hdots & & &hdots & ((hatPhi(p)_ij))_i,j=1^r \
 & ddots & & vdots\
 & & ddots & &((partial^alphapartial^betahatPhi(p)_ij))_i,j=1^r & vdots \
 texthuge0 & & & & \
 & & & & & ((partial_d^k-1hatPhi(p)_ij))_i,j=1^r
endpmatrix*
$$
enddocument

Something like this?

documentclass[10pt,a4paper]article
usepackage[utf8]inputenc
usepackage[T1]fontenc
usepackagemathtools,amssymb
begindocument
[
setlengtharraycolsep2.5pt % default value: 5pt
J(widehatPhi)(p)=
beginpmatrix
bigl((widehatPhi(p)^_ij)bigr)_i,j=1^r &dots &dots & dots & 
 bigl((widehatPhi(p)^_ij)bigr)_i,j=1^r \
& ddots & vdots & & vdots\
& &bigl((partial^alphapartial^betawidehatPhi(p)^_ij)bigr)_i,j=1^r & & vdots \
 & & & ddots & vdots \
 hboxhuge0 & & & & bigl((partial_d^k-1widehatPhi(p)^_ij)bigr)_i,j=1^r
endpmatrix
]
enddocument

If you are open to loading tikz, you could do

documentclass[10pt,a4paper]article
usepackage[utf8]inputenc
usepackagemathtools
usepackagetikz
usetikzlibrarytikzmark
begindocument
[ J(widehatPhi)(p)=
 beginpmatrix*[c]
 tikzmarknodetl((widehatPhi(p)_ij))_i,j=1^r & 
 hspace*9em&
 tikzmarknodetr((widehatPhi(p)_ij))_i,j=1^r \[4em]
 tikzmarknodebl~ & &
 tikzmarknodebr((partial_d^k-1widehatPhi(p)_ij))_i,j=1^r
endpmatrix*
begintikzpicture[overlay,remember picture,Dotted/.style=%https://tex.stackexchange.com/a/101263/194703
 line width=#1, line cap=round, dash pattern=on 0pt off 4pgflinewidth,
 Dotted/.default=1.5pt,shorten/.style=shorten >=#1/2,shorten <=#1/2]
 draw[Dotted,shorten=4ex] (tl) -- (tr);
 draw[Dotted,shorten=4ex] (tr) -- (br);
 draw[Dotted,shorten=5ex] (tl) -- (br) node[pos=0.5,inner sep=0pt,above
 right]
 $((partial^alphapartial^betawidehatPhi(p)_ij))_i,j=1^r$ ;
 node[scale=3,above] at (bl.south west) $0$;
endtikzpicture
]
enddocument

You could also work with nicematrix (which uses TikZ).

documentclass[10pt,a4paper]article
usepackage[utf8]inputenc
usepackagemathtools
usepackagenicematrix
begindocument
[ J(widehatPhi)(p)=
 beginpNiceMatrix[name=mymatrix]
 ((widehatPhi(p)_ij))_i,j=1^r & 
 Cdots Hspace*7em& ((widehatPhi(p)_ij))_i,j=1^r\[2em]
 &Ddots & Vdots \[2em]
 ~ & & 
 ((partial_d^k-1widehatPhi(p)_ij))_i,j=1^r\
endpNiceMatrix
begintikzpicture[overlay,remember picture]
 path (mymatrix-1-1) -- (mymatrix-3-3)
 node[pos=0.5,above right,inner sep=0pt]
 $((partial^alphapartial^betawidehatPhi(p)_ij))_i,j=1^r$ ;
 node[scale=3,above] at (mymatrix-3-1) $0$;
endtikzpicture
]
enddocument

How about this

where

• I have usedmathrlap to hide the subscript and superscript from affecting column width so that the ddots appear below them,


• used smash on the large zero so it does not effect vertical spacing, and


• eliminated unneeded packages for this example.

Code:

documentclassarticle
usepackagemathtools

newcommand*A((hatPhi(p)_ij))mathrlap_i,j=1^r%
newcommand*B((partial^alphapartial^betahatPhi(p)_ij))mathrlap_i,j=1^r%
newcommand*C((partial_d^k-1hatPhi(p)_ij))_i,j=1^r
newcommand*BigZhspace*2.0emsmashtextHuge0

begindocument
[ 
 J(hatPhi)(p)=
 beginpmatrix*[c]
 A & & hdots & hdots & A \
 & ddots & & & vdots \
 & & B & & vdots \
 BigZ & & & ddots & vdots \
 & & & & C \
endpmatrix*
]
enddocument