amsmathmath-modespacing
Suppose, I have something like
\overline{q}_{l m_1}'(i) \overline{q}_{l m_2}'(i) \overline{q}_{l m_3}'(i)
Now, this renders to
which looks rather unpleasant. How can I reduce the spaces in front of the opening parentheses? The q's are functions of i, hence there should be no space at all.
I am using amsmath and mtpro2 for Times font in math mode, but the problem occurs regardless of these settings.
Many thanks in advance,
Lennex
An accented symbol is treated by TeX as an ordinary one; you have to tell it that you want a relation symbol:
\( w_{1} \mathrel{\tilde{\in}} w_{2} \)
The commands for declaring a math symbol are
\mathord (ordinary)\mathbin (binary operation)\mathrel (binary relation)\mathop (operator, use with care)An ordinary symbol is typeset without any spacing around it. A binary operation is something like +; for example, if one wanted to define a "mod" operation, a correct way would be
\newcommand{\bmod}{\mathbin{\textrm{mod}}}
(amsmath does it in a quite different way, but that's not the point). A binary relation is like <; the spacing around binary relation symbols is larger than around operation symbols. Moreover the space around relation symbols is uncompressible, while it is for operations.
As already said, putting an accent over a symbol makes it lose its predefined nature: the accented cluster is considered as an ordinary symbol; therefore we have to state explicitly its nature.
The next example only adds some boxes to make the spacing more visible:
\documentclass{article}
\setlength{\fboxsep}{0pt}
\setlength{\fboxrule}{.1pt}
\begin{document}
$\fbox{$\fbox{$u$}^{\fbox{$\scriptstyle*$}}$}\mathpunct{\fbox{$,$}}\fbox{$x$}$
\end{document}
The spacing between the superscript * and the comma , has three causes:
\scriptspace after super- and subscripts. Default is 0.5pt in LaTeX and plain TeX. It is the space between the box around * and the surrounding box.* and , there is some horizontal padding, called side bearings. It is a font property and not accessible in TeX.However, caution is needed for the negative spacing, LaTeX defines (pseudo code):
\! = \mskip-\thinmuskip
\thinmuskip = 3mu
\medmuskip = 4mu plus 2mu minus 4mu
\thickmuskip = 5mu plus 5mu
and package amsmath adds (pseudo code):
\negmedspace = -\medmuskip
\negthickspace = -\thickmuskip
\thinmuskip and therefore \! are not using stretchability. However, the others are. Then the spacing can become quite ugly, if stretching/shrinking is applied.
The negative sign causes the opposite effect making the spacing worse:
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\hbox{$u^*\negmedspace,x+y$}
\hbox spread -5pt{$u^*\negmedspace,x+y$}
\hbox spread 5pt{$u^*\negmedspace,x+y$}
\end{document}
For this, \! can be used. However, \negthickspace and \negmedspace should be avoided, they cancel the effect of \thickmuskip and \thinmuskip.
\negthickspace and \negmedspace
The following macros \negmed and \negthick add a negative space in math mode using the values from \medmuskip and \thickmuskip without the stretch and shrink components:
\def\negstrip#1 #2\relax{-#1}
\newcommand*{\negmed}{%
\mkern-\medmuskip
}
\newcommand*{\negthick}{%
\mkern-\thickmuskip
}
The question, how much negative spacing could be used is also partly a matter of taste. I tend to something inbetween \! and \negmed, perhaps \mkern-3.5mu\relax.
Best Answer
You may set small spaces (1/6 of a quad) manually: negative
\!and positive\,: