<p>After studying algebraic geometry, algebraic topology and category theory, 
after teaching  mathematics and computer science 
in university and high school, 
after studying bioinformatics and implementing image analysis algorithms in a biotech start-up, 
I have since been working in finance, in London, Tōkyō and Hong Kong.</p>

<p>My preferred programming languages are R and Perl, 
but I try to use the best language and tools 
to solve the problem at hand.
I also like to learn more marginal languages, such as Haskell or Oz/Mozart. I am interested in human languages, too.</p>

<p>Here is a selection of my answers.</p>

<ul>
<li><p>Computing a probability density function 
from its 
<a href="http://stackoverflow.com/questions/10029956/calculating-a-density-from-the-characteristic-function-using-fft-in-r/10038141#10038141">characteristic function</a>
or by 
<a href="http://stats.stackexchange.com/questions/26598/maximum-entropy-sampler/26605#26605">maximizing its entropy</a>;</p></li>
<li><p>Quadratic programming 
<a href="http://stackoverflow.com/questions/9817001/optimization-with-constraints/9817442#9817442">to ensure a sequence is increasing</a>
or to <a href="http://stackoverflow.com/questions/9971268/plot-an-item-map-based-on-difficulties/9971741#9971741">position labels on a plot</a></p></li>
<li><p>Reparametrizing 
<a href="http://stackoverflow.com/questions/9666120/constrain-optimisation-problems-in-r/9667097#9667097">optimization problems</a>
to make them 
<a href="http://stackoverflow.com/questions/9592369/in-r-how-do-i-find-the-optimal-variable-to-maximize-or-minimize-correlation-bet/9593809#9593809">unconstrained</a>,
for instance 
<a href="http://stats.stackexchange.com/questions/25007/fitting-the-parameters-of-a-stable-distribution">to fit stable distribution</a>;
penalizing them to restrict them to a <a href="http://stackoverflow.com/questions/11110848/how-to-optimize-for-integer-parameters-and-other-discontinuous-parameter-space/11111069#11111069">discrete search space</a></p></li>
<li><p>Speeding up computations in R
<a href="http://stackoverflow.com/questions/9526691/efficiently-compute-histogram-of-pairwise-differences-in-a-large-vector-in-r/9527046#9527046">using C</a>
or by 
<a href="http://stackoverflow.com/questions/10011425/vectorize-function-to-avoid-loop/10011954#10011954">expanding</a>
some of the computations</p></li>
<li><p><a href="http://stackoverflow.com/questions/9106401/select-rows-of-a-data-frame-based-on-column-properties/9106581#9106581">Computing the skyline</a></p></li>
<li><p><a href="http://stats.stackexchange.com/questions/16631/what-are-essential-rules-for-designing-and-producing-plots/22010#22010">On the use of colour in statistical plots</a></p></li>
<li><p><a href="http://stackoverflow.com/questions/9747426/how-can-i-produce-plots-like-this/9748213#9748213">Plotting the result of a time series clustering</a></p></li>
<li><p><a href="http://stackoverflow.com/questions/10150161/ordering-117-by-perfect-square-pairs/10150797#10150797">Solving puzzles with graph theory</a></p></li>
</ul>

Vincent Zoonekynd