Ggthjy

I would like to write the dimensions of a matrix below the matrix itself, but I managed only to either:

1. write the dimensions below the matrix with underbrace (see matrix A in my code)


2. write the dimensions as a subscript of the matrix (see matrix B in my code)

What I want is (1) but without any underbrace sign, and possibly the n*n written in a smaller font. I attach below a MWE

documentclass{beamer}



usepackage{amssymb}

usepackage{mathpazo}

usepackage{multimedia}

usepackage{amsfonts}

usepackage{amsmath}



setcounter{MaxMatrixCols}{10}



title{Title}

subtitle{Subtitle}

author{Author}

date{}

institute[Universities Here and There]{Your Institution}





begin{document}



begin{frame}

titlepage

end{frame}



section{Introduction}



begin{frame}frametitle{Write dimensions below matrix}

begin{center}

$

begin{bmatrix}

underbrace{A}_{ntimes n} & B_{ntimes n} \ 

C & D%

end{bmatrix}%

$

end{center}



end{frame}

end{document}

Use underset, with scriptscriptstyle in order to reduce the size.

Note that loading mathpazo does nothing unless you select suitable font themes.

documentclass{beamer}



usefonttheme{serif}

usefonttheme{professionalfonts}

usepackage{mathpazo}



begin{document}



begin{frame}frametitle{Write dimensions below matrix}



[

begin{bmatrix}

underset{scriptscriptstyle ntimes n}{A} &

underset{scriptscriptstyle ntimes n}{B} \[1.5ex]

C & D

end{bmatrix}

]



end{frame}

end{document}

Avoid awkward constructions such as begin{center}$<formula>$end{center}: displaymath is much better, with its shorthand [...].

with using of the package stackengine:

documentclass{beamer}



usepackage{amssymb}

usepackage{mathpazo}

%usepackage{multimedia} not relevant for your problem

%usepackage{amsfonts}   loaded by amssymb

usepackage{amsmath}

%setcounter{MaxMatrixCols}{10}

usepackage{stackengine}







begin{document}



begin{frame}

frametitle{Write dimensions below matrix}

[stackMath

begin{bmatrix}

stackunder{A}{_{ntimes n}}  & stackunder{B}{_{ntimes n}} \[2ex]

         C              &          D

end{bmatrix}%

]

end{frame}

end{document}

or see, if writing matrix symbol in mathbf{...} better emphasize matrices:

begin{frame}

frametitle{Write dimensions below matrix}

[stackMath

begin{bmatrix}

stackunder{mathbf{A}}{_{ntimes n}}  & stackunder{mathbf{B}}{_{ntimes n}} \[2ex]

         C              &          D

end{bmatrix}%

]

end{frame}

which gives