Square Bracket Size Mismatch

Question

I have a continued fraction surrounded by square brackets of unequal size. I want them to be of equal size. I've tried the \delimitershortfall set to a negative value. I've tried \Bigg for the right-hand side as opposed just \big for the left-hand side. Any suggestions to make the brackets of equal size greatly appreciated.

Here's the code:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$\big{\lfloor \frac{1+\frac{1}{1+\frac{1}{1+\frac{1}{1+.....}}}}{\frac{f_{10}}{f_9}} \Bigg{\rfloor}}$

\end{document}

Answer 1

For the continued fraction use \cfrac; then enclose the big fraction in gathered so that it will be vertically centered, so \left\lfloor and \right\rfloor will do their job properly.

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\[
\left\lfloor
\!\begin{gathered}
\frac{1+\cfrac{1}{1+\cfrac{1}{1+\cfrac{1}{1+\dotsb}}}}
     {\dfrac{f_{10}}{f_9}}
\end{gathered}
\right\rfloor
\]

\end{document}

Your \big{\lfloor...} works just by accident. Use \bigl\lfloor for opening and \bigr\rfloor for closing (or the \Bigl-\Bigr and so on variants). While \bigl{\lfloor} works, \left{\lfloor} definitely won't.