Welcome

This is my home in the virtual world, where I write about things that I want to share. The freely available software that I've written as well as some of the photographs I've taken over the years can also be found here. Please use the navigation links on the right if you are looking for something.

Recent articles

1. Adding text or graphics to a PDF file (again)

   In an earlier article I talked about using a picture environment in LaTeX to add lines and text over an image. In another article I showed how to draw with PostScript, including using Encapsulated PostScript to include arbitrary images.

   In this article I want to cover the pros and cons …

2. ImageMagick: convert vs Wand

   The ImageMagick suite has been in my software toolbox for years. It is my go-to tool for manipulating bitmap images. Over the years I have written several front-ends for specific tasks for in Python.

   In general, I have used the subprocess module to launch convert or mogrify from Python.

   With …

3. Installing Pelican 4

   Pelican is the static site generator that I use for my website. This allows me to write my website posts in almost plain text (actually a light-weight markup language named reStructuredText), which are then translated into HTML. As someone who has written his webpages in HTML by hand, I can …

4. Creating a nomogram with Python and Postscript

   At work I needed a suitable way to check the calibration of gelcoat spray equipment. Gelcoat requires an initiator (often called “catalyst”) in the form of a peroxide to cure. The peroxide/gelcoat ratio is important, so it is checked regularly by spraying the separate components into suitable containers and …

5. Drawing with PostScript

   PostScript (in the form of ghostscript) was for me the first way to generate vector graphics outside of a CAD program. I have several hundreds of figures written in PostScript for inclusion in e.g. LaTeX document.

   Later I’ve started using other programs like metapost and asymptote. But in …

6. TeXLive 2018 update

   Today I updated my TeXLive install to 2018. Although the install went fine, there was a problem with the binaries.

   Both asymptote and xetex were linked to different versions of some libraries than those that are supplied by ports. So I had to rebuild them.

   Reason

   Some might wonder why …

7. Using the FT232 with Python

   In this article I will try to document how to with with the FT232H using Python on FreeBSD. I will be using the Adafruit FT232H breakout board.

   Note that since I’m using FreeBSD, the library provided by FTDI doesn’t work. However, the library provided by Adafruit was written …

8. Measuring particulate matter with the PMS5003

   This article details how I used the Plantower PMS5003 particulate matter (“PM”) sensor on a PC or laptop, using an FT232H breakout board to make the connection.

   Introduction

   My reasons for buying this device are so that I can measure airborne particulate matter at home and at work. So I …

9. Storing and graphing time-based data

   In this article we will look into the best way to store time-based data and use it with gnuplot.

   Timezone

   The first thing to realize is that we should specify a timezone when specifying dates and times (“datetimes”). To prevent calculations, I tend to use datetimes in UTC.

   Format

   Next …

10. Yes, please: #DeleteFacebook. But don’t leave it at that.

    Cut facebook out of your life altogether.

    Step 1: delete your facebook account

    For me, the first step is easy: I don’t use facebook, and never have. :-)

    Here is a guide to delete your facebook account properly.

    Step 2: make facebook and its subsidiaries unreachable from your network

    Set …