agrega una línea adicional debajo de la primera columna de la tabla. ¿Por qué?

Question

\begin{table*}
    \centering
    \caption{Eigenvalues of Study System with and without SSSC}
    \begin{tabular}{c|c|c|c|c}
        \toprule 
        \multirow{3}{*}{Mode}&\multicolumn{4}{c}{75\% Compensation level}\\
        \cmidrule{2-5}
        &\multicolumn{2}{c}{case:1(without SSSC)} &\multicolumn{2}{|c}{case:2(with SSSC)} \\
        \cmidrule{2-5}
        &$\sigma\pm j\omega$& $\zeta$ &$\sigma\pm j\omega$& $\zeta$  \\
        \midrule 
        Supersynnchronous&-9.5903$\pm$629.17i&0.01524 &-12.344$\pm$556.39i&0.02218\\
        Subsynnchronous&1.6034$\pm$123.7   &-0.01296&-9.0587$\pm$137.23i&0.06586\\ 
        Shaft    &-0.4911$\pm$6.1496i&0.07962  &-0.48842$\pm$6.1493i&0.07917\\
        Torsional &-85.88 $\pm$38.471i&0.91261  &-85.883$\pm$37.936i&0.91474\\
        Electromechanical&-11.602$\pm$91.825i&0.12535  &-9.6224$\pm$94.729i&0.10106\\ 
        \midrule
        \multirow{7}{*}{Other}&-2416.6$\pm$1271.4i&0.88511  &-2421.1$\pm$1252.1i&0.88825\\
        &      0$\pm$0i     &  -      &-2670.3            &1      \\ 
        &   0$\pm$0i        &   -     &-110.25            &1      \\
        &      -0.12579     &    1    &-0.15132           &1      \\
        &     -0.0035219    &   1     &-0.0034435         &1      \\
        &                   &         &0$\pm$0i           &-      \\ 
        &                   &         &0$\pm$0i           &-      \\                  
        \bottomrule 
        \label{comparison75}
    \end{tabular}
\end{table*} 

Answer 1

El problema es que el \labelcomando está dentro del archivo tabular. Si lo pones en el alcance de tableentonces la línea adicional desaparece.

No estoy completamente seguro de por qué ocurre exactamente este problema, probablemente el \labelcomando se ve como el comienzo de una fila adicional para la cual se imprime la primera línea separadora de columnas.

MWE:

\documentclass{article}
\usepackage{booktabs}
\usepackage{multirow}
\begin{document}
\begin{table*}
    \centering
    \caption{Eigenvalues of Study System with and without SSSC}
    \label{comparison75}
    \begin{tabular}{c|c|c|c|c}
        \toprule 
        \multirow{3}{*}{Mode}&\multicolumn{4}{c}{75\% Compensation level}\\
        \cmidrule{2-5}
        &\multicolumn{2}{c}{case:1(without SSSC)} &\multicolumn{2}{|c}{case:2(with SSSC)} \\
        \cmidrule{2-5}
        &$\sigma\pm j\omega$& $\zeta$ &$\sigma\pm j\omega$& $\zeta$  \\
        \midrule 
        Supersynnchronous&-9.5903$\pm$629.17i&0.01524 &-12.344$\pm$556.39i&0.02218\\
        Subsynnchronous&1.6034$\pm$123.7   &-0.01296&-9.0587$\pm$137.23i&0.06586\\ 
        Shaft    &-0.4911$\pm$6.1496i&0.07962  &-0.48842$\pm$6.1493i&0.07917\\
        Torsional &-85.88 $\pm$38.471i&0.91261  &-85.883$\pm$37.936i&0.91474\\
        Electromechanical&-11.602$\pm$91.825i&0.12535  &-9.6224$\pm$94.729i&0.10106\\ 
        \midrule
        \multirow{7}{*}{Other}&-2416.6$\pm$1271.4i&0.88511  &-2421.1$\pm$1252.1i&0.88825\\
        &      0$\pm$0i     &  -      &-2670.3            &1      \\ 
        &   0$\pm$0i        &   -     &-110.25            &1      \\
        &      -0.12579     &    1    &-0.15132           &1      \\
        &     -0.0035219    &   1     &-0.0034435         &1      \\
        &                   &         &0$\pm$0i           &-      \\ 
        &                   &         &0$\pm$0i           &-      \\                  
        \bottomrule 
    \end{tabular}
\end{table*} 

\end{document}

Resultado: