RM papers
Optimal Dynamic Pricing of Inventories over Finite Horizons
How to create a versioned table from a crud table in Postgres with triggers
Example You have a user table in Postgres: CREATE SCHEMA tutorial; CREATE TABLE tutorial.crud_users ( id INT NOT NULL, username VARCHAR NOT NULL, CONSTRAINT crud_table_pkey PRIMARY KEY (id) ); You insert new users and update usernames for existing users. Update is a destructive operation that overwrites data, so how do you keep track of what …
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Unusual instruments in Vietnam
The nose flute The Duo A’Reng, a primitive talkbox!
Getting back into operations research
For the last five years, I have been fascinated with machine learning techniques, but that fascination is slowly running out. I increasingly consider ML a tool in my tool box among others, not a panacea to all problems. In particular, I’d like to return to other algorithmic techniques from my educational back, i.e. computer science. …
Good Book, Bad Program
Programming is like writing a book. Both programs and books are written in a language, e.g. Datalog or Tagalog, but the similarity goes deeper than that. Imagine that you must write a book with the subject "a man walks his dog". There are endless ways to write that book, but only a few of them …
Comparing the Corona outbreak in Scandinavia and South/South-East Asia
I have read the WHO’s sitreps on CoViD-19 daily since the end of January 2020, where I was visiting Viet Nam. I now live in Denmark (a Scandinavian country) where the Corona virus has shut down society and many people have tested positive. When I compare the numbers for Scandinavia (Denmark, Norway, Sweden) with a …
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Our Sagawind 20
Through hulls on Sagawind 20 This year we bought an old sail boat from 1979 – a Sagawind 20. My first order of concern is to check the location and state of the through hulls, which are perhaps the most critical part of a sail boat. There is literally a hole through the hull! Special …
How to compute and plot Bollinger Bands® in Python
The aim is to produce a plot like this. The orange line is your data, the green line is the upper "bollinger" band, the blue line is the lower "bollinger" band. The red dots indicate where your data is either above or below the bands. Copy-paste this code: import pandas as pd import numpy as …
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See who is hosting a website
To see who is hosting a website (e.g. netflix.com), you will need the IP address of the website and the WHOIS record for that IP address. You can obtain both from the command-line. Obtain the IP address for netflix.com: # Ping the website ping netflix.com # Alternatively, use traceroute and note the last IP address …