Performance Comparison in Computing Exponential Function

, 2 min read

If your computation is dominated by exponential function evaluations, then it makes a significant difference whether you evaluate the exponential function exp() in single precision or in double precision. You can reduce your computing time by roughly 25% when moving from double precision (double)…

youtube-dl HTTP 403 error

, 1 min read

youtube-dl is a set of Python scripts for downloading videos from YouTube, Twitter, Vimeo, and many other sites, see for example the list of supported sites. This is a handy tool if you want to watch videos or listen to music on your smartphone: Download them with youtube-dl and store them on your…

J-Pilot Plugin For SQLite Export

, 2 min read

In SQL Datamodel For J-Pilot I described the SQLite datamodel. I wrote a J-Pilot plugin which can export the below entities and write them to an SQLite database file. The direction is one-way: from J-Pilot to SQLite. Address Datebook Memo To-Do Expense Various categories for above entities Adding…

SQL Datamodel For J-Pilot

, 12 min read

Currently J-Pilot stores its data in binary form which is compatible with the original Palm data format. See Palm File Format Specification. Reading these binary formats is not simple, see for example pdbrd.c. Portion of the internal structure looks something like this: typedef struct { //…

Sharing Terminal Screen Using Tmux

, 3 min read

Sharing your terminal input and output can be done in different ways. kibitz, see Linux commands: expect and kibitz VNC Skype / Teams / Zoom, etc. tmux 1. tmux essentials. tmux (tmux wiki) uses the following vocabulary and hierarchy. server session-group session client window pane The…

J-Pilot Data on Android Phone: Contacts

, 2 min read

Keeping J-Pilot data in sync with Android smartphone is quite a challenge. See my post about Google calendar. Copying contact data from J-Pilot to Android in the past went like this: Export data from J-Pilot in vCard (vcf) format If required, fiddle with this vcf file with some Perl…

ssh and rsync for Android, Termux

, 1 min read

I used SSHelper for some time to rsync my files from my Linux machine to Android phones, see here. I most notably used this for transfering photos. I now use Termux. I prefer Termux over SSHelper as it allows to install new programs within Termux using pkg or apt-get. Starting Termux looks like…

Surfing the internet with 1 GBit/s

, 2 min read

Adding 30 Cents to my monthly bills bought me Gigabit internet access. I now pay 39.99 EUR per month. Previously I had 100 MBit/s. From user's experience I do not feel any significant difference. Of course, for all my mobile devices, like smartphones, laptop, there is and will be no difference as…

Aggressive Vodafone Router

, 1 min read

Vodafone router does not allow to turn off firewall permanently. It will insist on switching it on after 24 hours. Version of this router in question: Firmware version: 01.02.037.03.12.EURO.SIP Productname: Vodafone Docsis 3.1 This "Made in China" router using…

Statistics of this Blog: Crossed 100.000 Views

, 1 min read

This blog was viewed more than 100.000 times since its inception and had more than 76.750 visitors. The averages per month are: As numbers: The most popular posts over one year are: The most popular posts over all years are: Distribution of countries accessing this blog over last 365 days, USA…

Contribution to scientific publications in GPUGrid

, 1 min read

Looking at my account page in GPUGrid I notice that my computations have lead to some publications. Nice. Task Papers Topic 3063rd/3113 Giorgino et al, J. Chem. Theory Comput, 2012 cancer 3389th/5798 Sadiq et al, PNAS 2012 hiv 1801st/1995 Venken et al, JCTC 2013 hiv 1886th/3349 Buch et…

Chinese Hackers

, 3 min read

I am running fail2ban since November 2017 and all unsuccessful attempts to log-in to sshd are monitored. Breaking down these attempts according country shows that Chinese IP addresses are coming first here. The numbers are: 27639 China 13589 United States 8641 France 3985 India 3418 …

slurmctld showing nodes as 'drain'

, 1 min read

Recently one node was changed from octacore to hexacore. Since that time sinfo showed this node in STATE drain. Stopping and restarting slurmctld did not resolve the issue. Log file /var/log/slurm-llnl/slurmctld.log showed [2019-12-31T23:57:52.588] error: Node X appears to have a different…

Oracle Deadlock When Using Bitmap Index

, 1 min read

When using bitmap indexes in Oracle database one must watch out for deadlocks, see for example Tom Kyte's remark on Bitmap indexes and locking. This is by design of bitmap indexes. Below example is given in Oracle Bitmap Indexes Limitations/Restrictions. Problem occurs on "Oracle Database 12c…

Updating IP Address in Dynu

, 1 min read

Dynu is a free dynamic DNS service. As described in Microsoft Brought Down No-IP.org I have to cope with big business just pushing their own interest and not caring on small business or private customers. I tried to update IP address for Dynu using ddclient using package ddclient. This failed. The…

Statistics of this Blog: Crossed 90.000 Views

, 1 min read

This blog was viewed more than 90.000 times since its inception and had more than 68.630 visitors. The averages per month are: The most popular posts over one year are: The most popular posts over all years are: USA is at the top of viewers of my blog this year, as before:

Google Chrome in Android Cannot Clear Cookies

, 1 min read

Google Chrome on Android version 74.0.3729 can no longer clear history, cookies, local data, etc. See screenshot below. Even when this process is running completely uninterrupted, nothing happens. I.e., changing display sleep time to 30 minutes, Google Chrome will not finish. Problem solution:…

Showing History of Visits in Mozilla Firefox

, 1 min read

If one needs to know when some website has been visited in Mozilla Firefox then go to the default directory and open the places.sqlite file: cd ~/.mozilla/firefox/<xyz>.default/ sqlite3 places.sqlite Issue below SQL command select visit_date, datetime(visit_date/1000000,…

WordPress.com down for a few minutes

, 1 min read

On 04-Mar-2019 I shortly experienced a downtime of my two blogs here on WordPress.com. Just a few minutes. Because this is so rare I made a screenshot of this event. See below. Below two blogs were affected: Elmar Klausmeier's Weblog Collected Links

java.sql.SQLRecoverableException: IO Error: Connection reset by peer, Authentication lapse

, 1 min read

I encountered the following error, when I wanted to connect to Oracle v12.2.0.1.0 database with Java 1.8.0_192-b26: java.sql.SQLRecoverableException: IO Error: Connection reset by peer, Authentication lapse 321631 ms. This was unexpected as the same program did run absolutely fine on another Linux…



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