[Tex/LaTex] no effect of \baselinestretch

line-spacing

I'm probably doing something wrong, but i can't see any effect of the command \baselinestretch, which should modify the vspace between lines. I read somewhere, that i should add \selectfont after it, but i can't see any effect either:

\documentclass[12pt]{article}
\begin{document}

{\renewcommand{\baselinestretch}{2}\selectfont coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou }

\end{document}

Best Answer

This problem is similar to when one writes

{\Large some long text
 that will span two or
 more lines}

and the line spacing comes out wrong.

TeX uses one baseline skip for all lines in a paragraph, using the value in force when it scans the end of paragraph. In the example and also in your code the \par (or equivalent blank line) is found when the group where the change has been issued has already been closed and its effect canceled. The following code

\documentclass[12pt]{article}
\begin{document}

{\linespread{2}\selectfont coucou coucou coucou coucou 
coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou 
coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou 
coucou coucou coucou coucou coucou coucou coucou coucou coucou coucou \par}

\end{document}

won't have the problem. Notice the \linespread{2} command, which is handier than \renewcommand{\baselinestretch}{2} and has the same effect.