How to avoid the indentation made by \**displayskip?

Question

I wrote a class file, but I found if I want to change the space between the math environment and text by the solution provided by Stefan Kottwitz, the indentation appears in front of the 'abstract'. Here is the mwe,

            \begin{filecontents}{mycls.cls}
            \NeedsTeXFormat{LaTeX2e}
            \ProvidesClass{mycls}
            \LoadClass{article}
            \newdimen\@bls
            \@bls=\baselineskip
            \renewcommand\section{\@startsection {section}{1}{\z@}%
                                   {1.2\@bls  plus .3\@bls minus .1\@bls}%
                                   {5pt\@afterindentfalse}%
                                   {\sffamily\large\bfseries\raggedright}}
            \newbox\absbox
            \def\abstract{\lrbox\absbox\minipage{\textwidth}%
            \sffamily%
            \hspace{-\fill}\section*{\normalsize\noindent Abstract}\vskip -1.5mm\relax%
            }
            \def\endabstract{\endminipage\endlrbox}

            \def\keywords#1{%
            \gdef\@keywords{\begin{minipage}{\textwidth}{\normalsize\sffamily \textbf{Keywords}}\\ \parbox[t]{\textwidth}{#1}\end{minipage}}}
            \let\@keywords\@empty

            \def\@maketitle{{\noindent\usebox\absbox\par}
            {\vspace{20pt}%
            {\noindent\normalsize\@keywords}\par}{\vskip2em\relax}}
            \end{filecontents}
            \documentclass{mycls}
            \usepackage{lipsum}
            \begin{abstract}
            \lipsum[1]
            \end{abstract}
            \keywords{Hello}
            \begin{document}
            \maketitle
            \lipsum[1]
            \begin{equation}\label{eq:test}
            a^2+b^2=c^2
            \end{equation}
            \lipsum[1]
            \end{document}

The class and code above gives

But if I add the code

            \expandafter\def\expandafter\normalsize\expandafter{%
                \normalsize
                \setlength\abovedisplayskip{40pt}
                \setlength\belowdisplayskip{40pt}
                \setlength\abovedisplayshortskip{40pt}
                \setlength\belowdisplayshortskip{40pt}
            }

in the class file, the output will be

Some space appears in front of the 'abstract' and 'keywords'.

I want to know where the space comes from and how to cancel it.

First of all, you should use proper LaTeX, no TeX constructs. — Johannes_B, Sep 06 '16 at 06:28
Where are the necessary places to be appended with % to remove unwanted spaces? — Johannes_B, Sep 06 '16 at 06:31
Also, don't call \normalsize in its own definition and provide a proper size for normalzise. — Johannes_B, Sep 06 '16 at 06:32
Thansk for your comments. The code is copy from a class file written by a publisher and I want to modify it. — Ice0cean, Sep 06 '16 at 06:33
{5pt\@afterindentfalse}% is wrong, that argument should be a positive or negative length. And there are lots of % missing from ends of lines so they will generate spaces in your output. every use of \normalsize as defined above will add 4 spaces. — David Carlisle, Sep 06 '16 at 06:48
I reads the links you provide, the information in that is useful. Thanks :) @Johannes_B — Ice0cean, Sep 06 '16 at 12:33

score 1 · Accepted Answer · answered Oct 30 '16 at 21:42

{5pt\@afterindentfalse}% is wrong, that argument should be a positive or negative length. And there are lots of % missing from ends of lines so they will generate spaces in your output. every use of \normalsize as defined above will add 4 spaces.

 \expandafter\def\expandafter\normalsize\expandafter{%
                \normalsize
                \setlength\abovedisplayskip{40pt}%%one space
                \setlength\belowdisplayskip{40pt}%% one more
                \setlength\abovedisplayshortskip{40pt}%% a third
                \setlength\belowdisplayshortskip{40pt}%% a fourth
            }

How to avoid the indentation made by \**displayskip?

1 Answers1