General ⇒ \left( \right)

[threshold]

Hi I have the following problem, the Kile under ubuntu does not accept the following structure (simplified):

\begin{eqnarray}
y&=& \left( \frac{1}{x} (a+b) \nonumber \\
&+& (c+d) \right)
\end{eqnarray}

when I put ( ) instead of \left( \right) then it works, but I want the size of the brackets to adjust.

best

[localghost]

You have to use invisible delimiters to get that kind of line break.

Code: Select all

\documentclass[11pt]{article}
\usepackage{amsmath}

\begin{document}
  \begin{align}
    y&= \left( \frac{1}{x} (a+b) \right. \nonumber \\
     &+ \left. (c+d) \right)
  \end{align}
\end{document}

The reason why not to use the eqnarray environment can be read in l2tabu. Other useful hints about typesetting mathematical expressions can be found in "Math mode".


Best regards and welcome to the board
Thorsten¹

[Juanjo]

I would improve the typesetting of the formula. Please, take into account that:
* the use of \left and \right leads, in this case, to matching delimiters of different sizes, which is not correct;
* the continuation line should be indented in order to appear at the right of the opening delimiter.
So I would propose any of the following solutions (there's still more):

Code: Select all

\documentclass[11pt]{article}
\usepackage{amsmath}

\begin{document}
\begin{align}
  y= \Bigl( &\frac{1}{x} (a+b) \Bigr. \notag \\
      &+ \Bigl. (c+d) \Bigr)
\end{align}
  
\begin{equation}
  \begin{split}
    y= \Bigl( &\frac{1}{x} (a+b) \Bigr. \\
       &+ \Bigl. (c+d) \Bigr)
  \end{split}
\end{equation}

The second solution shows how to vertically center the equation number.