underfull \hbox (badness 1342) in paragraph

Question

This message of warning appears at the line 967, which says:

Las ecuaciones en \eqref{eq1.32} sugieren un m\'etodo para calcular las factorizaciones \QR reducidas. Dados $a^1,a^2,\dotsc$, podemos construir los vectores $\seq[q]{n}$ y los escalares $r_{ij}$ por un proceso de ortogonalizaci\'on sucesiva. Esta es una idea antigua, conocida como la \textit{ortogonalizaci\'on de Gram-Schimd}.

In the log file:

Underfull \hbox (badness 1342) in paragraph at lines 967--968
[]\OT1/cmr/m/n/12 Las ecua-ciones en [] su-gie-ren un m^^Setodo para cal-cu-lar las fac-to-ri-za-cio-nes
[]

Answer 1

Since you're writing in Spanish, which has many accented words, it's necessary to employ fonts in T1 encoding, that have glyphs for the accented characters. Otherwise TeX won't hyphenate words with accented letters past them.

Here's an example with your paragraph; I've made some suppositions about how the macros are defined.

\documentclass[a4paper,twocolumn]{article}
\usepackage[T1]{fontenc}
\usepackage[spanish]{babel}
\usepackage{amsmath,xspace}
\newcommand{\QR}{\textbf{QR}\xspace}
\newcommand{\seq}[2][x]{#1_1,#1_2,\dots,#1_{#2}}

\textwidth=.8\textwidth

\begin{document}

\begin{equation}\label{eq1.32}
a=b
\end{equation}

Las ecuaciones en \eqref{eq1.32} sugieren un m\'etodo para calcular las 
factorizaciones \QR reducidas. Dados $a^1,a^2,\dotsc$, podemos construir 
los vectores $\seq[q]{n}$ y los escalares $r_{ij}$ por un proceso de
ortogonalizaci\'on sucesiva. Esta es una idea antigua, conocida como 
la \textit{ortogonalizaci\'on de Gram-Schimd}.

\end{document}

If I remove the line \usepackage[T1]{fontenc}, then I get the warning

Underfull \hbox (badness 1147) in paragraph at lines 16--21
[]\OT1/cmr/m/n/10 Las ecua-cio-nes en [] su-gie-ren un

and the result is as follows (notice the bad spacing):

PS: It's "Gram-Schmidt"! I find it written in many different ways in my students' papers. :)