Math & Science ⇒ Erroneous Code for Equation

[Amitavo Roy]

I am new in LaTeX. Could some body explain me what is wrong in this code as it always show me "missing } inserted"

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\begin{equation}
{\vec R}_{k,n,i}=
\mu_0 \sum_j \frac{I_{B,j}}{u_{\parallel,j,n,i}}
\left[G_{e,k,j,n,i}e^{-jm\varphi_{e,i}} \cdot
e^{j(\omega_k-\Omega_f)t}\right]_n \cdot
\left(j\Omega_0 \cdot \frac{\vec p_{j,n,i}}{\gamma_{j,n,i}}+
{\underbrace{\left(\frac{\gamma^2_{j,n,i}-1}{u^2_{\parallel,j,n,i}}\right){\overbrace{\left(\frac{1}{2B_{R,n}}\frac{dB_{R,n}{dz}}\right)}^{Mag_n}}\cdot
\frac{{\vec p}_{j,n,i}}{\gamma_{j,n,i}}}_{D_n}}\right)
\end{equation}

[Stefan Kottwitz]

Check that all your opening and closing braces match. Write with more spaces to better see it, or temporarily split your complex equation in parts to localize the error.

Btw. don't choose a topic title "Help me" but a title which briefly describes a problem. Your topic has been renamed.

Stefan

[Amitavo Roy]

Thanks stefan for your help...

I follow your instruction...but still showing me the same error...
waiting for your valuable suggestion

[Stefan Kottwitz]

I understand. So if you already made your code better readable, by inserting spaces, indenting lines, or similar, you could post it here again. The code above is still hardly readable, most people would habe problems in locating unmatched braces.

Stefan

[svend_tveskaeg]

It took me some time to dissect the code. (As Stefan says, it is very messy.)

I finally found the problem; \frac{dB_{R,n}{dz}} should be \frac{dB_{R,n}}{dz}.

Here is an attempt to make it more readable:

Code: Select all

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{gather}
\begin{split}
 \vec{R}_{k,n,i}
 &= \mu_0 \sum_j\frac{I_{B,j}}{u_{\parallel,j,n,i}}
 \left[
  G_{e,k,j,n,i}e^{-jm\varphi_{e,i}} \cdot e^{j(\omega_k-\Omega_f)t}
 \right]_n\\
 &\hphantom{{}=\mu_0 \sum_j}
  \cdot
 \left(
  j\Omega_0 \cdot \frac{\vec p_{j,n,i}}{\gamma_{j,n,i}}+
   \underbrace{
    \left(
     \frac{\gamma^2_{j,n,i}-1}{u^2_{\parallel,j,n,i}}
    \right)
    \overbrace{
     \left(
      \frac{1}{2B_{R,n}}
      \frac{dB_{R,n}}{dz}
     \right)
    }^{Mag_n}
   \cdot \frac{{\vec p}_{j,n,i}}{\gamma_{j,n,i}}
   }_{D_n}
 \right)
\end{split}
\end{gather}

\end{document}

Output.

output.jpg (44.9 KiB) Viewed 6319 times

Note the use of \hphantom (and especially {} before =) to get the correct vertical alignment when the equation is split over two (in general, more than one) lines. Furthermore, the {gather} and {split} environments inside one another are used to vertically center the equation number.

P.S. If you use Emacs, putting the following code in your .emacs file will let you detect matching brackets easier:

Code: Select all

(show-paren-mode t)

[Amitavo Roy]

Thanks a lot svend_tveskaeg...
Yes it is perfect now...