I am using the following equation which works perfect when it is a single-line equation:
\begin{equation}
\mathrm{NPIF}^\ast_i \mathrel{\mathop:}= \sum_{j=1}^{\mathrm{N}_\mathrm{L}} \biggl\{ w_{\mathrm{L},j} \, \tilde{l}_j \left[ \mathrm{PTDF}^{\left[ k_+ \right]}_{ij} \, \bigl( x_{\mathrm{L,max},j}^{\left[ k_+ \right]} \bigr)^{\mathrm{n}_1} + \mathrm{PTDF}^{\left[ k_- \right]}_{ij} \, \bigl( x_{\mathrm{L,min},j}^{\left[ k_- \right]} \bigr)^{\mathrm{n}_1} \right] \biggr\}
\end{equation}
I would like to break this equation into two lines using the split
environment:
\begin{equation}
\begin{split}
\mathrm{NPIF}^\ast_i \mathrel{\mathop:}= \sum_{j=1}^{\mathrm{N}_\mathrm{L}} \biggl\{ w_{\mathrm{L},j} \, \tilde{l}_j \left[ \mathrm{PTDF}^{\left[ k_+ \right]}_{ij} \, \bigl( x_{\mathrm{L,max},j}^{\left[ k_+ \right]} \bigr)^{\mathrm{n}_1} \\
+ \mathrm{PTDF}^{\left[ k_- \right]}_{ij} \, \bigl( x_{\mathrm{L,min},j}^{\left[ k_- \right]} \bigr)^{\mathrm{n}_1} \right] \biggr\}
\end{split}
\end{equation}
The last code gives me a ! Extra }, or forgotten \right.
error. I tried to close the two brackets in the first line by using \right. \right.
and a corresponding \left. \left.
on the second line but this did not solve the error... Any ideas?
\left{ \right.
or\left. \right}
where the.
(dot) closes a\left \right
pair without printing it. See tex.stackexchange.com/questions/380641 for example.