I've been trying to produce a table in which the first two columns has rows merged, the next three columns has columns merged, with three sub-columns, within the same height as the merged rows of cols 1 and 2, with a final column that has rows merged like cols 1 and 2-viz.
I am using pdflatex, the tabularx package, booktabs package and array package. My relevant code is:
\documentclass[12pt]{article}
\usepackage{multirow}
\usepackage{tabularx}
\usepackage{booktabs}
\begin{document}
\begin{table}[h]
\caption{Spectral channel characteristics of SEVIRI in terms of central, minimum and maximum wavelength of the channels and the main application areas of each channel.}
\begin{tabularx}{\textwidth}{l l c c c l}
\toprule
\multirow{3}{3.5em}{Channel No.} & \multirow{3}{3.5em}{Spectral Band ($\mu$m)} & \multicolumn{3}{c}{Characteristics of} & \multirow{3}{10em}{Main observational application} \\
{} & {} & \multicolumn{3}{c}{Spectral Band ($\mu$m)} & {} \\
\cmidrule(lr){3-5}
{} & {} & $\lambda_{\mathrm{cen}}$ & $\lambda_{\mathrm{min}}$ & $\lambda_{\mathrm{max}}$ & {}\\
\midrule
1 & VIS0.6 & 0.635 & 0.56 & 0.71 & Surface, clouds, wind fields \\
2 & VIS0.8 & 0.81 & 0.74 & 0.88 & Surface, clouds, wind fields \\
3 & NIR1.6 & 1.64 & 1.50 & 1.78 & Surface, cloud phase \\
4 & IR3.9 & 3.90 & 3.48 & 4.36 & Surface, clouds, wind fields \\
5 & WV6.2 & 6.25 & 5.35 & 7.15 & Water vapor, high level clouds, atmospheric instability \\
6 & WV7.3 & 7.35 & 6.85 & 7.85 & Water vapor, atmospheric instability \\
7 & IR8.7 & 8.70 & 8.30 & 9.1 & Surface, clouds, atmospheric instability \\
8 & IR9.7 & 9.66 & 9.38 & 9.94 & Ozone \\
9 & IR10.8 & 10.80 & 9.80 & 11.80 & Surface, clouds, wind fields, atmospheric instability \\
10 & IR12.0 & 12.00 & 11.00 & 13.00 & Surface, clouds, atmospheric instability \\
11 & IR13.4 & 13.40 & 12.40 & 14.40 & Cirrus cloud height, atmospheric instability \\
12 & HRV & \multicolumn{3}{c}{Broadband (about 0.4--1.1 $\mu$m)} & Surface, clouds \\
\bottomrule
\end{tabularx}
\end{table}
\end{document}
I would like the lambda-containing columns to be evenly distributed. I tried to add sizing to the c c c columns, but then I get the illegal pream-token error when I run:
[1{c:/texlive/2018/texmf-var/fonts/map/pdftex/updmap/pdftex.map}]
! Package array Error: Illegal pream-token (2em): `c' used.
See the array package documentation for explanation.
Type H <return> for immediate help.
...
l.104 \end{tabularx}
Any ideas?
siunitx
for better unit handling.