Stolz-Cesàro theorem
L’Hôpital’s rule:
for functions \(f\) and \(g\) which are differentiable on \(I \backslash\{c\}\) ,
where \(I\) is an open interval containing \(c\), if
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Erlang & Poisson distribution
Poisson distribution (PDF):
\(f(k;x,\lambda) = \frac{(\lambda x)^k e^{-\lambda x}}{k!}\quad\textrm{for }x,\lambda\ge 0\)
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Replace a Search Tree with Skiplist for Performance
Reading http://www.codeproject.com/Articles/27799/Stree-A-fast-std-map-and-std-set-replacement,
learned about the paper Deterministic skip lists
by Munro, Papadakis, and Sedgewick in 1992.
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Snapshot backup
This is a method of backup that I invented many years ago and used at
workplace. I think it is quite useful because it abused the nature of hard
links in UNIX.
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bash and TCP/UDP sockets
bash can do TCP and UDP sockets. They are represented as a special file in /dev, like
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