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Quick (probably easy) Latex Question

  1. Nov 2, 2012 #1
    Hi,

    I'm trying to write some equations in LaTeX. They are inside an align environment. My code is the following:

    \begin{align*}
    \omega_\mu{}^{ab}(e) &= \frac{1}{2} \eta^{ac} \eta^{bd} e^\nu_c e^\rho_d ( \Omega_{[\mu \nu] \rho} - \Omega_{[\nu \rho] \mu} + \Omega_{[\rho \mu] \nu})
    \\ &= \frac{1}{2} e^{\nu a} e^{\rho b} ( \Omega_{[\mu \nu] \rho} - \Omega_{[\nu \rho] \mu} + \Omega_{[\rho \mu] \nu})
    \intertext{now we use the result $\Omega_{[\mu \nu] \rho} = 2 \partial_{ \left[ \mu } e_{ \nu \right] }{}^a e_{a \rho}$ from eqn $(7.89)$}
    \\ &=e^{\nu a} e^{\rho b} \left( \partial_{[\mu} e_{\nu]}{}^c e_{c \rho} - \partial_{[\nu} e_{\rho]}{}^c e_{c \mu} + \partial_{[\rho} e_{\mu]}{}^c e_{c \nu} \right)
    \end{align*}

    The problem is the last couple of lines where i split square brackets over two different subscripts. LaTeX doesn't like this and complains - a LOT!

    So I guess my question boils down to how to write the LaTeX code for something like this:

    q_{ [a } p_{ b] }

    without getting lots of errors!

    Thanks very much!
     
  2. jcsd
  3. Nov 2, 2012 #2

    Simon Bridge

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    Like this?
    $$q_{[a} p_{b]}$$
     
  4. Nov 2, 2012 #3
    Yes. Do I need a particular package to get that to work or something?

    If you look at the chunk of code I posted above, I have used exactly what you've written but it gives me errors about not having properly closed the parenthesis
     
  5. Nov 2, 2012 #4

    Simon Bridge

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    Looking through your code I get:$$\begin{align}\omega_\mu{}^{ab}(e) &= \frac{1}{2} \eta^{ac} \eta^{bd} e^\nu_c e^\rho_d ( \Omega_{[\mu \nu] \rho} - \Omega_{[\nu \rho] \mu} + \Omega_{[\rho \mu] \nu})
    \\ &= \frac{1}{2} e^{\nu a} e^{\rho b} ( \Omega_{[\mu \nu] \rho} - \Omega_{[\nu \rho] \mu} + \Omega_{[\rho \mu] \nu})
    \\ &\ldots \text{ now we use the result $\Omega_{[\mu \nu] \rho} = 2 \partial_{[ \mu } e_{ \nu] }{}^a e_{a \rho}$ from eqn $(7.89)$}

    \\ &=e^{\nu a} e^{\rho b} \left( \partial_{[\mu} e_{\nu]}{}^c e_{c \rho} - \partial_{[\nu} e_{\rho]}{}^c e_{c \mu} + \partial_{[\rho} e_{\mu]}{}^c e_{c \nu} \right)\end{align}$$
    ... I think I see what you want to do: you want the square brackets in the partial (in the intertext) to resize so they are bigger than the e in the second part... the trouble was when you used the \left [ ... \right ] inside separate curly brackets latex did not see where the other side to each was. i.e. {\left [}{\right ]} is not allowed and that's the only reason I can think of for wanting to use \left \right in that context.

    ##2\partial \left [_\nu e_\rho \right ]## ... better?
    Though it does kinda make it look like the nu belongs to the e.

    [edit]
    I'm afraid you didn't. Take a closer look ;)

    [note: that equ. reference should really be a link too - jic ;) ]
     
    Last edited: Nov 2, 2012
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