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I write, therefore I am

With this variation on a famous statement by the philosopher Descartes, I would like to express that the act of writing about what happens in my life is important to me.

Wednesday, April 1, 2020

Bidirectional pseudo-random generator

A pseudo-random generator is a random generator which generates a very long sequence of numbers, which repeat exactly after a certain number of steps. This number is also called the cycle length. Often, when the state of the random number generator consists of n bits, it is possible to achieve a cycle length of a the n-th power of two minus one, meaning that the sequence contains all the possible values except for one. Because the sequences are usually too long to store in memory, an algorithm is used to calculate the next number. There are also cases where you would like to go back in the sequence and calculate the previous number in the sequence. Now, for one of the most simple random generators, Fibonacci LFSRs, which is based on shift-registers and the exclusive or operator, this is not very difficult. With these you have n bits and to calculate the next bit you take the exclusive or operation from the most right bit and some other bit and assign this to the most left bit after you have shifted all other bits one to the right. In a sense, it is like adding another bit to the left of the n and than shift the 'frame' of n bits one to the left. An important property of the exclusive or operator, which is often denoted with ⊕, is that when ab=c then a=bc. For this reason, when taking n bits, it is possible to calculate the bit that was on the right, by taking the exclusive or operation of the most left bit and the one other bit that was involved. Thus by shifting the frame back to the right, you get the previous value and can keep on doing this as long as you want. The following two C expression can be used to calculate the next and the previous value in a sequence defined by the constants A and B.
v = ((((1 << (B-1))-1) & v) << 1) | (1 & ((v >> (A-1)) ^ (v >> (B-1))));

v = (v >> 1) | ((1 & (v ^ (v >> A))) << (B-1));
For example, when A is 5 and B is 9, a sequence of 511 values of 9 bits are produced. But with larger values for A and B, much larger sequences can be produced.

Monday, March 30, 2020

-5.6° Celsius

This night the temperature dropped to -5.6° Celsius, which is equal to the lowest temperature measured on this day of the year on 1996. This morning, I noticed that all the flowers on our magnolia had turn brown. I already had expected this to happen earlier this week, because it is cold for the time of the year and the clear skies during the night have caused the temperature to drop below zero many nights in the past week.

Sunday, March 29, 2020

Ira Helsloot

I saw Prof. Dr. Ira Helsloot in a TV program make some interesting statements. He is professor of the Governance of Safety and Security at the Radboud University and editor for the Joural of Contingencies and Crisis Management. He is convinced that the current measurements, an 'intelligent' lock-down' in the Netherlands, are causing more problems to the health of people than they are preventing. He reasons that the general age of the people who die from COVID-19 is around 80 and are already in a poor condition, people who were going to die anyway in a few years. But the measurements are also causing economical damage, we are heading to a serious recession. Recession will lead to a drop in income and it is a known fact that people with a low income will have more health problems and on average live ten years shorter. He argues that by trying to extend the lives of a few thousand people now, we are causing milions of people to die earlier in the coming fourthy years. He says the decisions that are made now, are made out of fear for hard choices. We have become accustomed to the idea that our health care is sufficient, that we do not have to let people die because we cannot give the care. This is a kind of luxury problem. Of course, politicians are also afraid to tell people that our health care in these kind of times, cannot help everyone, because it gives the idea maybe in the future health care is going to fail in normal times. And as always we are valuing solutions for the short term over those for the long term.


Saturday, March 28, 2020


Friday, March 27, 2020

In full blossom

I would say that our magnolia is in full blossom, despite the cold nights of the past days, whioh has made some of the edge of the flower petals turn brown. I took two pictures, one of which is shown to the right.

Thursday, March 26, 2020

Out of control

It looks like that the COVID-19 crisis is getting out of control in the Netherlands. It was already known that the number of officially reported cases was much lower than the real number of cases, because of the limited number of tests that are performed. Today, there was also some discussion about the limited availability of reagents for RNA extraction produced by Roche Diagnostics company, because about 80% of the testing machines in the Netherlands are bought from that company. (Some positive news was that a national lab for testing disease out-breaks in animals, have said that they are able to perform between 500 and 1500 tests per day.) Now it also appears that the number of fatal cases are under reported, because persons who have not tested positive are not included. Some GPs have reported that there are patients with clear signs of the SARS-CoV-2 virus who have died at home, who are not included in the official figures. Sometimes conditions of patient can deteriorate so quickly that they die before entering a hospital. I can also imagine, that some people simply refuse to be admitted in a hospital or are not allowed to enter a hospital because they are already receiving palliative care, such as people with severe dementia. Furthermore, it is becoming clear that the number of patients requiring IC is going to be higher than the available locations and that regular patients are no longer getting the optimal care due to delayed treatments. I am afraid that triage will also start to happen in the Netherlands, just like it has happened in Italy. I live an area where the number of cases is still relatively low, yet patients from more severly affected areas are transfered to local hospitals to lighten the burden of the hospitals in the most affected areas. Futhermore, also morgues are reporting that they are already under pressure and fearing that the situation might become much worse. They too, like many others, are reporting a shortage of protective materials. To me it sounds like the out-break is out of control. The first estimates are that this is going to hit our economy hard. Some people are already raising the question whether the economic consequences of all the measurements is in balance with the number of casualties we are trying to prevent.


Wednesday, March 25, 2020


  • Zig is a general-purpose programming language designed for robustness, optimality, and maintainability.

Monday, March 23, 2020

Conflict about testing protocol

Today, Alexander W. Friedrich, the medical microbiologist and head of the department of medical microbiology and infection prevention at the UMCG in Groningen, made some bold statement with respect to testing for the SARS-CoV-2 virus. He stated that he was annoyed about the position of the RIVM, that you are only contagious from the moment you have symptoms and that you have to stay at home - and that because of this only contacts who have had contact with the person tested positive after he or she fell ill are identified. "That is simply not true, just as it is not true that children cannot transmit the virus. That is why from the start we in the northern provinces have said: we are counting back two days from that first day of illness and we also trace those contacts. Second, children are contagious even if they don't get sick themselves." (Translation by me with help of Google translate.) He feels that the situation in the four northern provinces: Friesland, Groningen, Drenthe, and Overijssel, is different from the rest of the country and that it search and contain is still a valid strategy and there is good reason to deviate from the national policy. He also feels that care workers should be tested more, because they could infect a lot of people. He also claims that there is no problem with the testing capacity. He claims that it caused by the decision made before the first cases appeared in the Netherlands, that only two labs, at the RIVM and the Erasmus MC, should be freed for testing. I remember that in the first weeks, all positive test had to be repeated by a test by the RIVM to let it count as an established infection. The government has responded with stating that they are not happy with this deviation and that everywhere the same policy with respect who is being tested should be followed, again stating that the testing capacity is limited. Meanwhile news about cheap and fast tests becoming available internationally are being reported.

Too cold

Although spring has just started, it has been rather cold compared to the previous months. We have been seeing clear blue skies for some days, with no contrails visible in the sky. Many of the flowes on our magnolia have opened, but only a little bit, as can be seen in the picture on the right. It will even get a little colder, especially during the nights, and I am afraid that the flowers will turn brown as they have done in other years.

Subday, March 22, 2020


Saturday, March 21, 2020


Friday, March 20, 2020


Thursday, March 19, 2020

HSLuv palette

I wanted to give HSLuv a try with respect to generate a limited colour palette as inspired by the colour palettes by Peter Struycken like I did more than two years ago. I used hsluv-0.1.0.min.js for this purpose, resulting in the palette displayed below. I have to admit that it looks more balanced than the one I created before.

This text is displayed if your browser does not support HTML5 Canvas.

Wednesday, March 18, 2020


The first flowers of our magnolia have opened today. Yesterday, they almost opened. I took some pictures. This is rather early.


Monday, March 16, 2020

Herd immunity

This evening, our prime minister Mark Rutte talked about herd immunity during his televison speech about the SARS-CoV-2 virus. Which percentage of a population needs to be infected for herd immunity depends on the measure of contagiousness. For SARS this percentage is between 50% and 80%. He suggested that in this way we can protect the old and weak. I wonder how this is going to work. It would mean that the old and weak have to go into isolation until the epidemic is over. And from which age should people go into isolation? And what about the fact that amongh those you need IC treatment at the moment here in the Netherlands about half are under the age of fifty. This might be explained that a lot of young people got infected during carnaval parties in the South of the country, parties which were mainly visited by young people. It also seems that the infection rate among people in their twenties are high, usually with mild symptoms.

Sunday, March 15, 2020

COVID-19 links

Two links with respect to COVID-19:

Friday, March 13, 2020

Past containment

Yesterday, the Dutch government announced 'lock-down' measurements with respect to the spread of the SARS-CoV-2 virus in the Netherlands. This sounds like we are past the containment phase. So far, there are only two countries in the world where a serious outbreak of the virus has been successfully halted, and these are the Peoples republic of China and South-Korea. The first did it through extreme lock-down measurements, the second did it through very extensive and wide testing. South-Korea was prepared, because they learned their lessons from the MERS outbreak in 2015. I am afraid that most national public health institutions did not learn from their experiences. In the past months, South-Korea tested 220,000 people on the SARS-CoV-2 virus. They are still testing about more than 10,000 people every day. Although others have suggested other reasons why the out-break is now under control, and not in Italy, where it started in a very similar way, I think that their agressive and wide testing of people have contributed a lot. Here in the Netherlands, especially at the start of the out-break, testing has been rather limited. And even now, people are not tested in large counts. Figures about how many people have been tested and are tested every day are not published. The RIVM has stopped reporting about the number of 'imported' and under investigation cases. At 14:00 they reported that 190 people were tested positive, leading to a total of 804 official cases. Of these, 179 are professional care givers. They also reported that five more people, all old and in poor health, died, bringing the total to ten. They did reported that 115 people are being treated in hospitals at the moment.

Thursday, March 12, 2020

Signals and Words

I went to the opening of the exhibition Signals and Words at XPO with works by Thiago Hersan and Claudio Beorchia. Thiago Hersen is covering the signal part with some devices processing WiFi packets based on the idea of astrolabe. Claudio Beorchia covered the words part with five works on display. I found them all interesting. The most interesting of the very different project, I found his project Guilty, where he rewrites the Italian penal code into first person perspective, and his book project Anthems, Updates, where he processed the national anthems of 27 European countries through Google Translate. At 17:59, I received copy 68/100 of the book Anthems, Updates from Claudio. e

Tuesday, March 10, 2020


Monday, March 9, 2020

Five rainbows

While driving home on the A1 motorway, we saw five rainbows, namely:
  • 17:20-25: Partial rainbow, first right, then also left, and just before disappearing becoming a full single rainbow.
  • 17:29: Full single rainbow against rather bright background, thus barely visible.
  • 17:33: Partial rather bright, right, double rainbow.
  • 17:36-37: Bright (and wide) right single rainbow fragment, starting with a vague second rainbow.
  • 17:39-40: Bright (and wide) left single rainbow fragment, from the same shower, it seems, as the previous rainbow.

Sunday, March 8, 2020

Judith Schepers

I brought a short visit to the exhbition with works by Judith Schepers at Robson.

Saturday, March 7, 2020


At 15:02, I received the book Saintscapes. Vedute di Lombardia-Views of Lombardy written by Claudio Beorchia, edited by Matteo Balduzzi, written in Italian and English, and published by Viaindustriae in 2019, ISBN:9788897753575, which I had bought on Wednesday, March 4 from Idea Books for € 36.75.

188 cases

The RIVM today announced that there are 188 confirmed cases of COVID-19 in The Netherlands. From the start of this month we went from 10, 18, 23, 38, 82, 128 to 188 cases. With 8, 5, 15, 44, 46, and 60 new case in the past days, that looks like an exponential curve, meaning that if you would only look at these numbers, you could only conclude that we are still in the break-out phase and the spreading is not under control. It is being said that the increase in the past days is due to more extensive testing. The public health institutes are still trying to track the origin of each case. Of the 188 cases, 112 have been abroad, most of them in Northern Italy. 47 cases got infected by one of the other confirmed cases, leaving 29 cases where it is unknown how they got infected. One of these cases is a 86 year old man, who died yesterday with having an infection. It is not clear if the infection was the main cause of his death, because he was initially admitted in a hospital for another condition.

Thursday, March 5, 2020


Wednesday, March 4, 2020


I recieved the book On the Road: The Original Scroll written by Jack Kerouac (edited by Howard Cunnell), written in English and published by Penguin Books Limited in 2008, ISBN:9780141189215, from Bol.com, which I bought for € 14.27.


I went to opening of the exhibition AH-Erlebnis at B93, with works by Willemijn Calis, Elmar Ipskamp and Julianne Menke. I especially liked the video work by Willemijn with a sleeping couple breathing at the same pace. I also talked with Claudio Beorchia, because I was interested in his book Saintscapes. Views Of Lombardy, which I saw last January. We had a nice talk and he gave me a copy (60/100) of his book De wachters van de Polder. At 23:02:01, after I came home, I ordered his book Saintscapes from Idea Books for € 36.75.

Monday, March 2, 2020

Ten cases

Yesterday, there were ten cases of the COVID-19 infections in the Netherlands. For three of these cases, it is not known how they got infected. One of these was a 49 year old woman who had stayed in the hospital for a week. The hospital now has been 'closed' for new patients. So far, no other people who had been in contact with the patient have been tested positive. I heard that the doctors treating the patient several times considered to test the patient, but they received a negative advice from the Erasmus MC, but it was against the 'protocol' only to test people who have been in a risk area or have been in contact with people who have been a risk area. Since last Friday, the protocal has been changed.

Saturday, February 29, 2020

Leap day

Conny and I went to the Schrikkelfestival in and around Roombeek. We visited the ten locations in the order they were given on the map. At the CeeSpot Containers we saw the works by Etta Maduro. She was present and gave some explaination about her works. At XPO we saw the drawing by Judith Schepers. (I saw here works before on April 29, last year and met her before on June 9.) At Dynamo Expo we saw watercolours by Veronica Berkvens. At the Arendsmanhuis we met with Danielle Spoelman, who I met before last year June with her project together with Judith Schepers. I showed her the stamp I in my diary. We also went to the Rijksmuseum Twenthe where we were allowed to visit all exhibitions. It was quite busy and we only looked at an exhibition about drawings. At 'Van de Jeugd Archtects' the 'Co, trio 054' was playing. I got on of the free Schrikkelbeeld cubes by Wout Zweers. There were also two works by Rinus Roelofs. The last location was the Tankstation. I liked some of the works by Nour-Eddine Jarram and a painting by Ray Andreas. We went to the reopening of Sickhouse at the new location. At bookshop Broekhuis were at the top floor we saw the impressive exhibition of drawings by Jacq de Groot.

Friday, February 28, 2020


I am a little worried about the procedure that the Dutch goverment (according to the advice of Netherlands National Institute for Public Health and the Environment) is taking to limit the spread of COVID-19. They are stating that transmission only occurs when people get ill. This, while there is scientific evidence, such as in the article: Transmission of 2019-nCoV Infection from an Asymptomatic Contact in Germany, that people can infect others before they have any signs and also that many people do not get ill to an extend that they need hospitalization. Maybe they do this to not spread panic and cause many people, who just have an ordinary cold, to request for a test. The reported cases in the Netherlands are related to the outbreak in Italy. It is difficult to know what is the best strategy to deal with this outbreak.

Wednesday, February 26, 2020


This morning, I heard about snow on the news. When I opened the blinds, I did some (wet) snow falling from the sky. There was some snow on cars, plants, the grass, and such.


  • JS Paint: A web-based MS Paint remake.

Monday, February 24, 2020


Sunday, February 23, 2020

2001: A Space Odyssey

This moring, I finished reading the novel 2001: A Space Odyssey by Arthur C. Clarke, which I started reading on January 30 after I bought it on Tuesday, August 22, 2019. I watched the movie adaptation on May 27, 1978. Especially the first part of the book feels even slower than the movie. There are many differences between the plot of the book and the movie. Those have been detailed elsewhere. But even without these, the book has a different taste, much more focussing on the scientific aspects and also explaining the last part in far more detail.

Saturday, February 22, 2020


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