arrowsvector
For some reason I can't get diagonal arrows/vectors to work. Only the arrowhead shows up – the line is missing. For example, in the following, the first vector is fine (horizontal) but the second just gives a floating arrowhead.
\setlength{\unitlength}{1mm}
\begin{picture}(60, 40)
\put(30, 20){\vector(1, 0){30}}
\put(30, 20){\vector(4, 1){20}}
\end{picture}
I've tried using \thicklines, \thinlines, doesn't make a difference.
I'm using MiKTeX 2.9 with TeXnicCenter.
I was able to use my scalerel package to hopefully give you what you want (scalerel was just sent to CTAN today, so until it propagates, you can find the style listing at How to horizontally merge two symbols?).
Using that package's features, my first cut was to create a command \myabs, which places abs bars around anything. It will stretch the size of the bars exactly to the argument. The downside of this first attempt is that you may have preferred the bars to extend a bit above and below the object being surrounded (addressed later in this answer). Here's the code for the first approach:
\documentclass{article}
\usepackage{scalerel}
\usepackage{mathtools}
\begin{document}
% [METHOD USED IN ORIGINAL QUESTION CODE HERE, REMOVED FROM THIS LISTING]
\newcommand\myabs[1]{%
\setbox1\hbox{$#1$}%
\stretchrel{\lvert}{\usebox1}\stretchrel*{\lvert}{\usebox1}%
}
\[ \myabs{\vec{k}}~~\myabs{\vec{x}}~~\myabs{\vec{A}}~~\myabs{\vec{q}} \]
\end{document}
and here's the output, as compared to your original
However, to answer ralfix's request to extend the vertical line a bit above and below the surrounding object, I just used the \addvbuffer routine from the verbatimbox package, setting the top and bottom add-on to 2pt:
\documentclass{article}
\usepackage{scalerel}
\usepackage{mathtools}
\usepackage{verbatimbox}
\setlength\boxtopsep{2pt}
\setlength\boxbottomsep{2pt}
\newcommand\myabs[1]{%
\setbox1\hbox{$#1$}%
\setbox2\hbox{\addvbuffer{\usebox1}}%
\stretchrel{\lvert}{\usebox2}\stretchrel*{\lvert}{\usebox2}%
}
\begin{document}
\[ \myabs{\vec{k}}~~\myabs{\vec{x}}~~\myabs{\vec{A}}~~\myabs{\vec{q}} \]
\end{document}
But egreg commented that the height of the abs bar should not change with the argument. If that is the preferred embodiment of abs, then scalerel can fix that too:
\documentclass{article}
\usepackage{scalerel}
\def\lvert{|}
\begin{document}
METHOD 2: FIXED EXTENT
\newsavebox\mybox
\savebox{\mybox}{$\stretchrel*{|}{\rule[-.6ex]{0ex}{3ex}}$}
\def\myabs#1{\usebox\mybox#1\usebox\mybox}
\[ \myabs{\vec{k}}~~\myabs{\vec{x}}~~\myabs{\vec{A}}~~\myabs{\vec{q}} \]
\end{document}
With a recent TeX distribution there's no need to do anything for getting driver support for drawing oblique arrows. So I suspect you have an older version of xy.
You can also try tikz-cd. I show both outputs.
\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[all,cmtip]{xy}
\usepackage{tikz-cd}
\begin{document}
\begin{displaymath}
\xymatrixcolsep{5pc}
\xymatrix{
& & A & \\
B \ar[r] \ar[urr] & C \ar[r] & D \ar[r] \ar[u] & E
}
\end{displaymath}
\[
\begin{tikzcd}[column sep=5pc]
{} & {} & A \\
B \arrow{rru}{} \arrow{r}{} &
C \arrow{r}{} &
D \arrow{r}{} \arrow{u}{} & E
\end{tikzcd}
\]
\end{document}
Best Answer
You could load the
pict2epackage. It extends the existing LaTeXpictureenvironment using driver files and solves the issue with limited slope values for lines and vectors.