Let’s say I have the formula Y(n+1)= λ*Y(n)(1-Y(n)) So the value of Y at time n+1 is some factor (λ) times Y at time n times 1 minus Y at time n. Y is between 0 and 1. λ can be anything. As a starting point I choose Y0 to be 0.5 and λ=1. (In […]
Continue ReadingSierpinsky
Sierpinsky Triangle A Sierpinsky trianlge looks like: The above example is not to much developed….but you will get the idea. A Siepinsky triangle can be constructed the following way: Draw a triangle and color it completely black In every black triganle you see in the image do the following Create a white triangle by choosing […]
Continue ReadingRecursive SQL in DB2
Problem Playing around in DB2 I wanted to know how to create a hiearchical query. This because I wanted to create view for explain plans, a bit resembling the explain plans which oracle provides. First step is understanding how to make the recursive SQL’s The setup: drop table relations; create table relations (id int, parent […]
Continue ReadingCreate bridge device on my KVM host
I installed KVM on my debian host. Since I have 8 cores and 32GB RAM I have room to play around 🙂 And since I have some experience with KVM it was the obvious choice. Installing KVM : easy … apt is your friend Creating an VM : easy … Maybe I’ll once write it […]
Continue Readingvi beep
I’m was going crazy because off the annoying bell sound vi(m) makes all the time. To solve it I put “set belloff=all” in my .vimrc martijn@radijs:~$ cat .vimrc set belloff=all martijn@radijs:~$
Continue ReadingDIG
Whenever I need to do something concerning DNS resolving I resort to dig. Some examples: Getting the IP adres for maboc.nl: martijnmbos@penguin:~$ dig maboc.nl ; DiG 9.11.5-P4-5.1+deb10u3-Debian maboc.nl ;; global options: +cmd ;; Got answer: ;; ->>HEADERHEADERHEADERHEADER
Continue ReadingDebian apt commands
I just installed a Debian machine. And since I’m a very longtime RedHat/Fedora man now I’m struggling with the commands to install stuff. Here are my notes: apt update Updates the meta-data and repositories apt upgrade Actually upgrades packages who need upgrading apt install <package> Installs a package apt list [package] Displays all packages known […]
Continue ReadingSome Chromebook shortcuts
Some Chromebook shortcuts (this is and probably will always be a work in progress) Shortcuts: Copy a selected piece of text : Xtrl + c Cut a selected piece of text : Ctrl + x End of line : Search + Arrow Right Paste a selected piece of text : Ctrl + p Select all […]
Continue ReadingSession statistics
You can have a look at v$sesstat (joined with v$staname) to see the value of some statistics at this moment. What is a little more difficult to see is how statistics change over time. So I wrote a script for it. What it does: Gather all statistics, of one or all sessions, and put them […]
Continue ReadingGPG : Signing / verifying
GPG Index As seen in a former article gpg can be used to encrypt and decrypt a message or file. Important to realise…you don’t need a password/passprase to encrypt. As soon as you posess the public key of the user you want to encrypt for, you can do just that. That leaves us with the […]
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