How can I remove the warning
Underfull \hbox (badness 10000) detected at line 4 \OT1/cmr/m/n/10
test
in the following MWE ?
\documentclass{article}
\begin{document}
\leavevmode\hbox to3cm{test}Hello
\end{document}
Removing `underfull \hbox` warning with \hbox: how to do it
boxeswarnings
Related Solutions
If \raggedright is acceptable...
\documentclass[twocolumn]{article}
\begin{document}
\begin{table}
\begin{tabular}{|p{0.25\columnwidth}|p{0.75\columnwidth}|}
\hline
\raggedright % PS
longish line of text & second cell that will often have a lot of text\\
\hline
\end{tabular}
\end{table}
\end{document}
A second version:
\documentclass[twocolumn]{article}
\usepackage{array}
\begin{document}
\begin{table}
\begin{tabular}{|>{\raggedright}p{0.25\columnwidth}|p{0.75\columnwidth}|}
\hline
%\raggedright % PS
longish line of text & second cell that will often have a lot of text\\
\hline
\end{tabular}
\end{table}
\end{document}
And you'd better add Werner's corrections.
A paragraph should be ended by leaving a blank line in the input, not with ~\\. What happens is that an empty line is produced and it's underfull by construction, because it has nothing in it.
If you really need a blank line between two paragraph, use \bigskip (better yet \medskip) between them:
... this is the end of a paragraph.
\bigskip % or \medskip
Here a new one starts ...
If you want a vertical space between all paragraphs, consider loading instead the parskip package (look at its documentation). Note that “leaving blank lines” here and there is a practice coming from the usage of word processors, where it's very easy to do it (and thus spoil the document's appearance).
For your formulas, you should use an alignment environment; if you want (almost) flush left equations, there's the option fleqn:
\documentclass[fleqn]{article}
\usepackage{amsmath}
\usepackage{lipsum} % just for the example
\begin{document}
\lipsum*[2]
\begin{gather*}
(A \pm B)^{-1} \neq A^{-1} \pm B^{-1},\quad
(A \pm B)^* \neq A^* \pm B^*\\
|(A^*)^*|=|A|^{n^2-2 n+1}
\end{gather*}
\lipsum*[3]
\end{document}
Warning
Use none of the following commands:
\hfuzz=\maxdimen
\tolerance=10000
\hbadness=10000
With them you're basically saying that you don't care about getting good paragraphs. Maybe you don't care, but your readers do.
Best Answer
The latex syntax for this adds the glue to stop the underful message (and
\leavevmode)