Annuity or Angle Operation Symbol in LaTeX

Question

How do I set the symbol for the angle or annuity operation in LaTeX? Specifically, this is the actuarial a angle s = (1-v^s)/i.

Answer 1

For a very comprehensive list of LaTeX symbols, see The Comprehensive LaTeX Symbol List. Worth printing out and keeping under your pillow. Page 95 has some code that may do what you want.

Answer 2

I've looked at Life's Contingency's Package, various Actuarial Outpost forum threads, and the Comprehensive Symbol List for LaTeX, and combined the best into the following macros:

\DeclareRobustCommand{\lcroof}[1]{
  \hbox{\vtop{\vbox{%
      \hrule\kern 1pt\hbox{%
        $\scriptstyle #1$%
        \kern 1pt}}\kern1pt}%
    \vrule\kern1pt}}
\DeclareRobustCommand{\angle}[1]{
  _{\lcroof{#1}}}

You can then use this macro for the problem's example by typing

 $a\angle{s}$

If you need a full set of actuarial symbols, you should use the Life's Contingency's Package lifecon. Using lifecon, you can set the above by typing

 $a_{\lcroof{s}}$