A-Stability and Composite Multistep Methods
, 1 min read
PhD thesis from William Benjamin Rubin from May, 1973. Completed under the direction of Prof. Dr. Theodore Bickart, Syracuse University. RubinDiss1973.pdf
Scanning Microfilm to PDF
, 1 min read
On 31-Mar-2025 I visited the Joseph Regenstein Library in Chicago to scan two PhD dissertations. I had kept these two PhD thesis since 1990. In 1990 I could only read these two thesis on a microfilm reader. At that time there was no PDF. The Regenstein library of the University of Chicago offers…
Die verwendeten zyklischen Formeln im Programm TENDLER
, 26 min read
It is entirely possible, and even very likely, in view of the fact that the parameters $C_{ij}$ were “manually” set in an interactive computer search for the maximum $\alpha$, that better and simpler cyclic composite methods exist. An interested reader is invited to try the development of such…
Stiffness in Neural Networks
, 2 min read
In below two posts I had already mentioned the close connection between neural networks and solving stiff ordinary differential equations: Neural Network Training using Stiff ODE Solvers Reply to: Neural Network Back-Propagation Revisited with Ordinary Differential Equations Below…
Building J-Pilot and Pilot-Link on Linux
, 106 min read
I was asked how I build J-Pilot and Pilot-Link on Linux. 1. J-Pilot 2. Pilot-Link J-Pilot (Wikipedia) is a graphical application to manage dates and appointments addresses to-do's memos of all sorts various plugins, e.g., expenses J-Pilot was written by Judd Montgomery. 1. J-Pilot Below are…
Praktische Gewinnung zyklischer, steif-stabiler Verfahren
, 48 min read
1. Definition von Stabilitätseigenschaften 2. Schreibweise zusammengesetzter Mehrschrittformeln 3. Stabilität und Polynome 4. Verschärfung von Stabilitätsdefinitionen 5. Konstruktive Herleitung steif-stabiler zyklischer Formeln 6. Basisformeln der Tendlerschen Zyklen 7. Äquilibrierung von…
Website Analytics
, 148 min read
I had written on website analytics with regard to this blog before: Statistics of this Blog: Crossed 110.000 Views Statistics of this Blog: Crossed 120.000 Views URL Count Statistics I do not use cookies or any JavaScript libraries to track users. Instead I only analyze the web-server logs using…
Installing Simplified Saaze on Android
, 4 min read
Simplified Saaze is a static site generator. This very blog uses Simplified Saaze. It is possible to generate all HTML files on Android using Simplified Saaze! This post shows the necessary steps. The main trick is to use termux. I had written on termux here: ssh and rsync for Android, Termux. 1.…
Example Theme for Simplified Saaze: Myra West
, 3 min read
Simplified Saaze is the static site generator used for this very blog. There are a number of themes for Simplified Saaze: Saaze example, a pure example theme, simple to use and modify J-Pilot, showcasing an open-source software project and having a hierarchical menu Koehntopp, a blog for a…
Converting Myra West's vlog to blog
, 3 min read
Myra West has a YouTube channel, where she mostly talks about friendship, relationship, personal journey as a yound adult. Below video "21 Years Old: I Have NO Friends" went viral and hit more than six million views. Myra West has no blog. Below are the steps to convert her YouTube talks…
Upgrading Oppo Reno4 to Xiaomi 14T Pro
, 5 min read
Today I upgraded my Oppo Reno4 smartphone to a Xiaomi 14T Pro model. The "old" Oppo was still good, but the offered price for the 14T Pro was too good to say no. I already own a Xiaomi Tablet 6, with which I am very happy. So changing from OnePlus / Oppo to Xiaomi was an easy choice. Add…
snd_hda_intel: no codecs initialized
, 1 min read
Problem at hand: No sound on my loudspeakers. Error message during login and booting: Nov 19 10:53:19 chieftec kernel: snd_hda_intel 0000:08:00.6: Codec #0 probe error; disabling it... Nov 19 10:53:19 chieftec kernel: snd_hda_intel 0000:08:00.6: no codecs initialized Solution: Add below three…
Reading Two Files Simultaneously With Perl
, 1 min read
Task at hand: Read two or more files at the same time in Perl. Solution: #!/bin/perl -W # Reading from multiple files simultaenously use strict; my ($f1,$f2); open(F1,"< $ARGV[0]") || die("Cannot open $ARGV[0]"); open(F2,"< $ARGV[1]") || die("Cannot open…
Hosting Static Content with pico.sh
, 5 min read
pico.sh is a similar blogging platform like Bearblog. In contrast to Bearblog the upload of Markdown content is done using ssh/scp/sftp. I wrote about hosting static sites on various platforms: Hosting Static Content with surge.sh Hosting Static Content with now.sh, now.sh renamed themself to…
Testing Static HTML Files with htmltest
, 4 min read
Task at hand: You have generated static HTML files with a static site generator. You want to check, whether the links in all your files are pointing to valid URLs, and you want all your images and PDFs be present. There is a utility written in the Go programming language called htmltest. I first…
UNIX Process Substitution
, 1 min read
Process substitution is available in ksh, bash, and zsh. More examples can be found here: Process Substitution. Process substitution uses /dev/fd/<n> files to send the results of the process(es) within parentheses to another process. Piping the output of one program to the input of another…
Vodafone Internet Outage #2
, 2 min read
Today, 14-Oct-2024, starting at 16:23 (CET), internet provided by Vodafone was unavailable. At 20:51 internet was available again. So for almost five hours I had no internet and the blog went dark. Luckily, the IP address stayed the same, so I had no delay in DNS. DOCSIS signal noise ratio is now…
Hosting Static Content with DigitalOcean
, 2 min read
I wrote about hosting static sites on various platforms: Hosting Static Content with surge.sh Hosting Static Content with now.sh, now.sh renamed themself to vercel.app Hosting Static Content with netlify.app Hosting Static Content with Cloudflare Hosting Static Content with Neocities Hosting…
On The Stability Of The Solar System
, 7 min read
Our solar system is not stable when considerung time ranges of several Gigayears. These are the results of simulations done by Laskar and Gastineau. 1. Nomenclature Notions for ellipses, see below figure: center M semi-minor axis b semi-major axis a (linear) eccentricity e, numerical eccentricity…
XHProf with NGINX
, 2 min read
XHProf is a PHP profiler. I had written on XHProf here: Profiling PHP Programs Profiling PHP Programs #2 XHProf was originally written by Facebook engineers. Even though it severely slows down your PHP program during execution, it is nevertheless a valuable tool to get an understanding, where…