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360° video
At TkkrLab we unpacked a Christmas gift from
RevSpace. Someone had brought a
Ricoh Theta V camera
and used it to record a 360° video.
Books
At 17:00:48, I bought the following two book from bookshop Broekhuis for € 5.00 each:
I came up with a simple trick in the
program to generate more random Street Tile
Patterns. I was not happy with first result,
because it had a strong tendency to place large tiles under eachother with a
one shift to the left. This resulted in many similar looking patches. The trick
was to generate the pattern for the following lines from right-to-left. This
results in a quite even distribution of the different types of tiles. The
reason why the trick works, is that the top-right letter of the tile defines
the tile, and generating from right-to-left, results in a even distribution of
the possibilities whenever there is a choice between the different types of
tiles.
But on second look, I discovered that the trick does not work perfect, because
the above pattern has several H shapes (rotated by 90°). This does not
completely come as a surprise, but I right now, I have no clue how to fix it.
Random Street Tile Pattern
I found a way to prevent the errors. I realized that there were squares of
four values that did not match the allowed tiles. I added a check to
the program enforcing this. Still there
are some problems at the borders, which I hide by showing only part of them.
More research will be needed to address these issue.
Persistent 'balanced' tree
In the past weeks, I worked on the implementation of a persistent tree data structure. I first wanted to base it on
a red-black
tree, but then decided on a kind of 'balanced' trees using an extra
height indicator. The idea is that this would also allow less optimal height
differences in favour of sharing larger parts between versions, by only
performing the balancing in the parts that are made version specific. This
afternoon, I finished a first version, which works correctly and keeps the
tree reasonable balanced under deletion, but does not implement the idea of
sharing larger parts between versions. I still would like to perform some
performance analyses to see if it can be optimized. All the code is in
a single file, which also
includes all the testing procedures and some debugging code.
(Improvement)
You are what you do
This morning, I finished reading the Dutch book
Je bent wat je doet (You are what you do) by Roos Vonk, which I started reading on December 20,
2017, the day I bought the book. Roos Vonk is a Dutch professor of social
psychology. What I like about the book, compared to other self-help books, is
that it contains many references to scientific experiments to support the
advice that it gives. It is also a very practical book. Although I have
finished reading the book, I am going to study again, trying to make a summary
of the main points in order to apply them to my own life.
The Four colour theorem states that faces of a
planar graph can be coloured with four colours. Given four colours, there are
24 ways to permute them. Because of this, there must be another method to
represent a colouring with less freedom. For each planar graph with degree
three it is possible to define an equivalence relationship between a face
colouring and an edge colouring with three colours. Given three colours, there
are six ways to permute them. Which gives reason to believe there is a more
compact way to represent a colouring. And there is indeed, because with each
edge colouring it is the case that at each vertex the three edges are assigned
a different colour. By assigning a number to the edge colours, the colours
will appear either clockwise or anti-clockwise around each vertex. This can
be represented by assigning one of two 'colours' to each vertex. One could
exchange these, meaning that there must still be a more compact method for
representing a face colouring of a planar graph with degree three. This can
done by marking the edges for which the edge colours around the vertices of
the edge run in a different direction. It appears that for a marked edge,
the colours of the faces on the 'opposite side' of the two vertices are always
the same, while for an unmarked edge they are always different. The edge
marking also has the property that each face has an even number of edges with
a marking. But that is about everything that can be stated in general.
Depending on the number of edges of a face, there are certain patterns of
edge markings that are allowed, but there are no simple rules to describe
which patterns can occur.
This evening, I finished reading the book
The
Philosophy of Andy Warhol by Andy Warhol, which I started reading on
December 9. 2017 after I bought it on November 26.
I found this a rather boring book. It is rather similar to A, A novel in the sense that it present every day talk as something
special. It has long transcripts of telephone calls with B, who according
to Pat Hackett is Brigid
Berlin. It is definitely not about philosophy, at most about Warhol's
attitude to life.
New bike
This morning, I went to get my new bike, a Vilo de ville B 200 in the colour apple green. Instead of a chain drive
it has a belt drive, which is more durable, maintenance free, very silent, and
has less friction.
Some snow
Around seven in the morning, I saw some snow on the
cars, but not on the ground. Around eight, I saw that it was snowing. When
went outside around half past eight, it was snowing. I measured 1.5 cm of snow
on the table outside. Around ten, the snow already started to melt. It snowed
on and off during the day. In the evening there were still some patches of
snow, mostly on (high) grass.
Cordwoord puzzle too
At TkkrLab I found a
Cordwoord
puzzle too in a box we received from the Electronics Research Group · University of Aberdeen. I decided to
give it a try and spend the rest of the evening studying it and performing
some soldering. I am about halfway and left it in my box in the space for
another day.
13.7° Celsius
Between 14:30 and 15:00, the temperature at the closest official weather
station was 13.7° Celsius, which is a record high for this day as long as
records have been kept.
In the evening, I went to the opening of the exhibition Maß und Ziel with works by Carina Schüring. The exhibition was held in the Old Town Hall in
Neuenhaus where Carina
grew-up and no lives again. The room was full of people, mostly with people
from Neuenhaus. I guess, I was the only Dutch person around. But I met some
Germans, especially those who studied in Enschede, who could speak Dutch. I
could understand most of the introduction by Anke Baumeister. Only after about half of the people had left, I could
find some time to study her new works. From a distance they often do not look
that interesting, but when you come closer and closer, the more interesting it
becomes. I really feel that the quality of her work has matured a lot in the
past year. I feels as if she has found the quietness to search deeper.
Book
At 10:41:44, I bought the book Atlas of Remote Islands: Fifty Islands I
Have Not Visited and Never Will written by Judith Schalansky in English
and published by Particular in 2010,
ISBN:9781846143489, from bookshop Broekhuis
for € 19.95.
At 11:12:05, I bought Issue 2 of year 2007 of the Dutch art magazine
Metropolis M from thrift store Het Goed
for € 0.50.
Book
At 10:08, I bought the book Examencatalogus Yeahboek 12|13 written in Dutch and published by
AKI ArtEZ on Thursday, June 27, 2013 from charity
shop Het Goed for € 2.50. Later, I discovered I already bought
a copy of this book on Saturday, November 18,
2017. On the front page there is a dedication by Sumchog Kersbergen, also
with a line in the
Devanagari script.
BYOB preperations
This evening, at TkkrLab, I spend some time
preparing for coming Fridays "Bring Your Own Beamer" event. First I tested my
notebook with a beamer to see if it worked with the updated version that I
showed on last years event. Basically, I have
made it run faster, because it was changing to slow to be noticed by people
just giving it a short look, and I fixed a bug, which prevented one of the
effects not to work properly. Next I played with some parts of an old beamer,
which I found on January 24, 2017. Some other
member told me that he still had the lens to go with it and showed where it
fit, which made me realize that I was totally wrong about how it worked. At
some point, because I did not have the right lamp, I decided to leave it for
home and work a little on my notebook. At home, I did some further
experimentation and got some idea of how I am going to use it.
This months interesting links
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