[OS X TeX] AMS-LaTeX question

[Alain Schremmer]

On May 28, 2012, at 1:09 PM, Gary Gray wrote:

> Hi All,
>
> In the attached PDF file, I have added an \underbrace command in the  
> second line to call out the argument of the square root in the first  
> line. I would like the square root in the second line to be the same  
> size as that in the first, but LaTeX automatically sizes it to  
> include the underbrace. Is there a way to force the square root in  
> the second line to be the same size as that in the first? Here is  
> the relevant source:
>
> \begin{align*}
> &= \frac{A} { \left( k - m \omega_{0}^{2} \right)^{2} + c^{2}  
> \omega_{0}^{2} } \sqrt{ \left[ \left( k - m \omega_{0}^{2} \right)  
> \left( m \omega_{0}^{2} + k - m \omega_{0}^{2} \right) + c^{2}  
> \omega_{0}^{2} \right]^{2} + \left( m c \omega_{0}^{3} \right)^{2} }
> \\
> &= \frac{A} { \left( k - m \omega_{0}^{2} \right)^{2} + c^{2}  
> \omega_{0}^{2} } \sqrt{ \underbrace{ \left[ k \left( k - m  
> \omega_{0}^{2} \right) + c^{2} \omega_{0}^{2} \right]^{2} + \left( m  
> c \omega_{0}^{3} \right)^{2} }_{Q} }.
> \end{align*}

How about a real dirty hack like

\begin{align*}
&= \frac{A} { \left( k - m \omega_{0}^{2} \right)^{2} + c^{2}  
\omega_{0}^{2} } \sqrt{ \left[ \left( k - m \omega_{0}^{2} \right)  
\left( m \omega_{0}^{2} + k - m \omega_{0}^{2} \right) + c^{2}  
\omega_{0}^{2} \right]^{2} + \left( m c \omega_{0}^{3} \right)^{2} }
\\
&= \frac{A} { \left( k - m \omega_{0}^{2} \right)^{2} + c^{2}  
\omega_{0}^{2} } \sqrt{ \underbrace{ \hspace{20mm}\left[ k \left( k -  
m \omega_{0}^{2} \right) + c^{2} \omega_{0}^{2} \right]^{2} + \left( m  
c \omega_{0}^{3} \right)^{2} \hspace{20mm}}_{Q } }.
\end{align*}


Regards
--schremmer