How can I fix the size of parentheses around stacked function symbols?

Question

I apologize if this is a duplicate, I looked at a number of other questions regarding parentheses size but didn't find an answer to my problem.

I'm trying to stack two function symbols within parentheses.

Here is what I have:

\documentclass{article}
\usepackage{amsmath,amssymb,mathtools}
\begin{document}

$\LARGE(\mathrel{\substack{s\\ \\ f}})$

\end{document}

Which I would like to be rendered like this:

When I enter the MWE provided, though, it renders the parentheses a good bit smaller and much rounder than the image above (which was generated by entering $\LARGE(\mathrel{\substack{s\\ \\ f}})$ at http://www.codecogs.com/latex/eqneditor.php), with the result that both the "s" and "f" hang well above and below (respectively) the parentheses.

How can I get the MWE to match the image?

Answer 1

You can not use font size commands in math mode, your input produces

LaTeX Font Warning: Command \LARGE invalid in math mode on input line 5.

In general \left(...\right) makes stretchy delimiters however you are loading amsmath which defines a command for this notation:

\documentclass{article}
\usepackage{amsmath,amssymb,mathtools}
\begin{document}

$\tbinom{s}{f}$



\end{document}