why i am getting this error while entering 6*6 matrix in beamer? "Missing { inserted. \end{frame}"

Question

\documentclass[11pt]{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{enumitem}
\usepackage{graphicx}
\usetheme{CambridgeUS}
\usefonttheme{serif}
\begin{document}
\begin{frame}
    \frametitle{State-space Model of Proposed System}
    \vspace{-5cm} \tiny
        \begin{equation} \tiny
        A =  - B\left[{\begin{array}{*{20}{c}}
    {{r_s}}&{\frac{{{\omega _e}}}{{{\omega _b}}}{X_{ss}}}&0&0&{\frac{{{\omega _e}}}{{{\omega _b}}}{X_M}}&0\\
    { - \frac{{{\omega _e}}}{{{\omega _b}}}{X_{ss}}}&{{r_s}}&0&{ - \frac{{{\omega _e}}}{{{\omega _b}}}{X_M}}&0&0\\
    0&0&{{r_s}}&0&0&0\\
    0&{\frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}{X_M}}&0&{r_r^'}&{\frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}X_{rr}^'}&0\\
    { - \frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}{X_M}}&0&0&{ - \frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}X_{rr}^'}&{r_r^'}&0\\
    0&0&0&0&0&{r_r^'}
    \end{array}} \right]
\end{equation}
\end{frame}
\end{document}

Welcome to TeX.SX! There are a lot of useless curly braces in your code, so the error might come from that. Maybe you should try to rewrite the matrix with a more simple syntax. Also, instead of using \left[ {\begin{array}{*{20}{c}} ... \end{array}} \right] you could use simply \begin{bmatrix} ... \end{bmatrix}. — Vincent, Apr 24 '20 at 16:13
No, I think what should solve your error is rather to rewrite the matrix with less unnecessary curly braces. For example, why writing \frac{{{\omega _e}}}{{{\omega _b}}} instead of \frac{\omega_e}{\omega_b}? There are so much { and }, it is certainly easy to make a typo and to have a { missing. — Vincent, Apr 24 '20 at 17:14

Zarko · Accepted Answer · 2020-04-24T18:16:14.960

I suppose, that you would like to have slide like this:

In your MWE the following was done:

removed error as is also suggested in @BambOo answer
removed are all unnecessary curly braces
used is the nccmath package (which load amsmath that can be used \mfrac, a medium sized fractions, and environment \medmath, which reduce size of equations
instead of array with wrong numbered columns (20, but you use only 6!) is used bmatrix
removed are all \tiny commands (one of them wrong placed)
removed \vspace{-5cm} which ruin the look of the slide-

A MWE:

\documentclass[11pt]{beamer}
\usetheme{CambridgeUS}
\usefonttheme{serif}

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{nccmath, amssymb}
\usepackage{enumitem}
%\usepackage{graphicx} loaded by beamer

\begin{document}
\begin{frame}
\frametitle{State-space Model of Proposed System}
    \begin{equation}\renewcommand\arraystretch{1.5}
    \medmath{
A =  - B \begin{bmatrix}
r_s & \mfrac{\omega_e}{\omega_b} X_{ss}
        & 0 & 0 & \mfrac{\omega_e}{\omega_b} X_M 
                    & 0     \\
-\mfrac{\omega_e}{\omega_b} X_{ss}
    & r_s
        & 0 & -\mfrac{\omega_e}{\omega_b} X_M
                & 0 & 0     \\
0   & 0 & r_s
            & 0 & 0 & 0     \\
0   & \mfrac{\omega_e - \omega_r}{\omega_b} X_M
        & 0 & r_r'
                & \mfrac{\omega_e - \omega_r}{\omega_b} X_{rr}'
                    & 0     \\
- \mfrac{\omega_e - \omega_r}{\omega _b} X_M
    & 0 & 0 & -\mfrac{\omega_e - \omega_r}{\omega _b} X_{rr}'
                    & r_r'  & 0 \\
0   & 0 & 0 & 0 & 0 & r_r'
        \end{bmatrix}}
    \end{equation}
\end{frame}
\end{document}

Addendum: Equation can be written in normal size, if we introduce new variable $\Delta\omega=\omega_e-\omega_r$ :

\documentclass[11pt]{beamer}
\usetheme{CambridgeUS}
\usefonttheme{serif}

\usepackage{nccmath}

\begin{document}
\begin{frame}
\frametitle{State-space Model of Proposed System}
    \begin{equation}\renewcommand\arraystretch{1.5}
    \medmath{
A =  - B \begin{bmatrix}
r_s & \mfrac{\omega_e}{\omega_b} X_{ss}
        & 0 & 0 & \mfrac{\omega_e}{\omega _b} X_M 
                    & 0     \\
-\mfrac{\omega_e}{\omega_b} X_{ss}
    & r_s
        & 0 & -\mfrac{\omega_e}{\omega_b} X_M
                & 0 & 0     \\
0   & 0 & r_s
            & 0 & 0 & 0     \\
0   & \mfrac{\omega_e - \omega_r}{\omega_b} X_M
        & 0 & r_r'
                & \mfrac{\omega_e - \omega_r}{\omega_b} X_{rr}'
                    & 0     \\
- \mfrac{\omega_e - \omega_r}{\omega _b} X_M
    & 0 & 0 & -\mfrac{\omega_e - \omega_r}{\omega _b} X_{rr}'
                    & r_r'  & 0 \\
0   & 0 & 0 & 0 & 0 & r_r'
        \end{bmatrix}}
    \end{equation}
\end{frame}

\begin{frame}
\frametitle{State-space Model of Proposed System (normal size)}
    \begin{equation}\renewcommand\arraystretch{1.5}
A =  - B \begin{bmatrix}
r_s & \mfrac{\omega_e}{\omega_b} X_{ss}
        & 0 & 0 & \mfrac{\omega_e}{\omega _b} X_M
                    & 0     \\
-\mfrac{\omega_e}{\omega_b} X_{ss}
    & r_s
        & 0 & -\mfrac{\omega_e}{\omega_b} X_M
                & 0 & 0     \\
0   & 0 & r_s
            & 0 & 0 & 0     \\
0   & \mfrac{\Delta\omega}{\omega_b} X_M
        & 0 & r_r'
                & \mfrac{\Delta\omega}{\omega_b} X_{rr}'
                    & 0     \\
- \mfrac{\Delta\omega}{\omega _b} X_M
    & 0 & 0 & -\mfrac{\Delta\omega}{\omega _b} X_{rr}'
                    & r_r'  & 0 \\
0   & 0 & 0 & 0 & 0 & r_r'
        \end{bmatrix}
    \end{equation}
where $\Delta\omega=\omega_e-\omega_r$.
\end{frame}

Yes sir.. i need frame like this only.. i got your point.. it helped me solved my error... — Chirag Rohit, Apr 25 '20 at 05:57

score 0 · Answer 2 · answered Apr 24 '20 at 17:15

While you code is pretty ugly due to the braces everywhere, the error comes from the fact that you type ^'. However ' is actually defined as ^{\prime} as stated here. Just replace ^' with ' and it compiles fine.

\documentclass[11pt]{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{enumitem}
\usepackage{graphicx}
\usetheme{CambridgeUS}
\usefonttheme{serif}
\begin{document}
\begin{frame}
    \frametitle{State-space Model of Proposed System}
    \vspace{-5cm} \tiny
        \begin{equation} \tiny
        A =  - B\left[{\begin{array}{*{20}{c}}
    {{r_s}}&{\frac{{{\omega _e}}}{{{\omega _b}}}{X_{ss}}}&0&0&{\frac{{{\omega _e}}}{{{\omega _b}}}{X_M}}&0\\
    { - \frac{{{\omega _e}}}{{{\omega _b}}}{X_{ss}}}&{{r_s}}&0&{ - \frac{{{\omega _e}}}{{{\omega _b}}}{X_M}}&0&0\\
    0&0&{{r_s}}&0&0&0\\
    0&{\frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}{X_M}}&0&{r_r'}&{\frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}X_{rr}'}&0\\
    { - \frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}{X_M}}&0&0&{ - \frac{{{\omega _e} - {\omega _r}}}{{{\omega _b}}}X_{rr}'}&{r_r'}&0\\
    0&0&0&0&0&{r_r'}
    \end{array}} \right]
\end{equation}
\end{frame}
\end{document}

Thank you sir..This solved my error... thanks again for well explaination....i got it.. — Chirag Rohit, Apr 25 '20 at 05:57

why i am getting this error while entering 6*6 matrix in beamer? "Missing { inserted. \end{frame}"

2 Answers2