Vertical height of \longtable

Question

How can I reduce vertical height of the \longtable. Note that all the document is double-spaced. I need the vertical spaces in the tables to be exactly adjusted as in the \tabular.

Example:

\documentclass[a4paper,oneside,11pt]{book}
\usepackage[english]{babel}
\usepackage[super]{natbib}
\usepackage[LGR,T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{delarray}
\usepackage{a4}
\usepackage{bbm}
\usepackage{epic}
\usepackage{eepic}
\usepackage{ecltree}
\usepackage{multicol}
\usepackage{indentfirst}
\usepackage{eurosym}
\usepackage{theorem}
\usepackage{graphicx}
\usepackage{fancyhdr}
\usepackage{vmargin}
\usepackage{rotating}
\usepackage{supertabular}
\usepackage{longtable}
\usepackage{array}
\usepackage{caption}
\usepackage{pgf}
\usepackage{float}
\usepackage{subfig}
\usepackage[dvips]{color}    
\usepackage{mathenv}
\usepackage{setspace}
\usepackage{subeqnarray}
\usepackage[norule]{footmisc}
\usepackage{enumerate}
\usepackage{lscape}
\usepackage{tikz}
\usepackage[toc,page]{appendix}
\usepackage[pdftex]{hyperref}
\hypersetup{colorlinks,citecolor=black,filecolor=black,linkcolor=black,urlcolor=black}

\pagestyle{fancy} \fancyhf{}

\renewcommand{\headrulewidth}{0.5pt}
\addtolength{\headheight}{0cm}

\setlength{\doublerulesep}{\arrayrulewidth}
\setlength\unitlength{0.5cm}


\lhead[\fancyplain{}{\thepage}]{\fancyplain{}{ \scriptsize
\leftmark}} \rhead[\fancyplain{}{ \scriptsize
\leftmark}]{\fancyplain{}{\thepage}}

\renewcommand{\baselinestretch}{2}

\setmarginsrb{3cm}{3cm}{3cm}{3cm}{1cm}{1cm}{2cm}{0cm}
\makeindex % Composer l'index de fin de document.0

\bibliographystyle{authordate1} % Définit le style de la bibliographie
\setlength{\doublerulesep}{\arrayrulewidth} \makeatletter
\renewcommand\@makefntext[1]
{\noindent\makebox[2em][r]{\@thefnmark.\,}#1} \makeatother
\makeatletter

\renewcommand*{\@seccntformat}[1]{
\csname the#1\endcsname.\quad} \makeatother
\renewcommand {\theenumi}{\roman{enumi}}


\begin{document}
\scriptsize\begin{longtable}{lccc|ccc}  
%
\centering 
\caption{abc} \label{tab:result1}\\
\hline
%
& \multicolumn{3}{c|}{\textbf{1}} & \multicolumn{3}{c}{\textbf{2}}  \\%
VARIABLES & a & b & c & a & b & c  \\
\hline
\endfirsthead
%
\multicolumn{7}{c}
%
{{\textbf{Table} \thetable\ -- \textit{Continued from previous page}}} \\
\hline \noalign{\vskip-3pt}
%
& \multicolumn{3}{c|}{\textbf{1}} & \multicolumn{3}{c}{\textbf{2}}  \\%
VARIABLES & a & b & c & a & b & c  \\
\hline
\endhead
%
\textit{Continued on next page} \\
\endfoot
%
\hline
\endlastfoot

1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \\
1 & 2 & 3 & 4 & 5 & 6 & 7 \ 
\end{longtable}
\end{document}

Answer 1

The idea of making a MWE is that you remove all the packages that are not relevant, your MWE isn't at all minimal.

It also generates two errors

! LaTeX Error: Option clash for package color.

and

! Misplaced \noalign.
\caption ->\noalign 

The latter is particular serious. longtable has no chance to generate correct spacing if given invalid input.

If you change your input to comment out the spurious lines

  %\usepackage[dvips]{color}    

and

 %\centering 

Then the document runs without error.

If the output is not as you wish you will need to clarify what you do want the output to be.

---

If you don't want the table double spaced you could use the cpmmands from teh setspace package or simply

\renewcommand{\baselinestretch}{1}

before the table.