How to preview LaTeX equation or document in TexMaker?

Question

My code:

 \begin{document}
    \begin{equation}
    2*x+y
    \end{equation}
 \end{document}

I found that F2 can compile as LaTeX. Compile result:

 Process started

 Process exited with error(s)

How to fixed and preview it?

Answer 1

F2 in TeXmaker is a shortcut. What it runs is seen in the 'Tools' menu.

By default it runs 'LaTeX' but for this to compile correctly you would need your equation to be part of a complete, albeit minimal, .tex file. For example,

\documentclass{article}
\begin{document}
\begin{equation}
  \dot P = K'P+PK'^T + Cov(Kv-Gw)
\end{equation}
\end{document}

compiles without errors and should produce a .dvi file.

You may, as usual, wish to add additional packages (e.g. amsmath) or more code to view the snippet as intended.

Answer 2

In LaTeX, the equation environment typesets its entire contents (everything between \begin{equation} and \end{equation}) in math mode. Therefore, issuing $...$ is not needed within the environment and causes the error. Therefore, remove the "inner" $'s and it should compile fine.