I'm David Llewellyn-Jones and this is my homepage. I'm a software engineer at Jolla, who's also interested in programming, security, privacy and graphics. I occasionally crave adventure and a good thunderstorm. You might be interested in my software, my research or my random musings.

Want to know more about me? Here's a personality sketch written by a psychologist when I was in school.

“David is of high intelligence, although lacking in true creativity. He has a need for order and clarity, and for neat and tidy systems in which every detail finds its appropriate place. His writing is rather dull and mechanical, occasionally enlivened by somewhat corny puns and by flashes of imagination of the sci-fi type. He has a strong drive for competence. He seems to have little feel and little sympathy for other people and does not enjoy interacting with others. Self-centered, he nonetheless has a deep moral sense.”

Wow. Harsh. But disturbingly accurate.

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12 Jun 2021 : A BIOS reset caused my hard drive to disappear #
A cautionary tale about how a forgetful BIOS left my laptop unbootable, how I fixed it, and how I've become too dependent on my laptop.
2 Jun 2021 : Waste data dump #
Another waste data dump, rather overdue, but better late than never. Rather an uneventful waste dump, with returnables up slightly (cool drinks in the sun) compensated by a reduction in paper waste (reasons unclear). My daily average over the latest period was 130.0 g/day, which is actully pretty good. I think maybe I generate less rubbish when my bins are full, so emptying them a late reduces the average!
15 May 2021 : Waste data dump #
My fortnightly waste data results are now up on the waste page. It're relatively uneventful this cycle, with slightly less card than normal and a bit of an upward spike in paper, as it was beginning to accumulate and needed to be dealt with. My daily average of 162.86g/day over the last two weeks is close to my usual output (which for comparison was 174g/day across the whole of 2020). As the year turns from spring to summer and the weather starts getting much hotter in Finland, it'll be interesting to see what effect that has.
2 May 2021 : Waste data dump #
Another waste data dump for a pretty good fortnight with a daily average of 154g/day. The numbers are very similar to the preceeding period, with an increase in paper being offset by a decrease in returnables. Otherwise pretty similar and I'm happy with that.
24 Apr 2021 : Waste data dump #
I've just uploaded my lastest waste data dump. It's a bit of a strange one, because I left it a bit too long before taking measurements (an extra week of waste collection) and have now taken yet another week to log it. Clear signs of laziness on my part. Still, it serves to emphasise the benefit of using a histogram (or in this case a histocurve), rather than a bar chart (or standard line plot). I usually measure my waste every two weeks, accumulating to an overall total of around 2400g. Given the extra week, my total for this period is 3242g. When I first totted the numbers up I was a bit distressed, before it occurred to me about the delay in measuring my waste. If I recorded that absolute value on a graph, it would look like my waste output had increased, whereas in fact my average output across the three weeks is 170.6g per day, almost identical to my 2020 average of 173.8g per day. Because output on the graph is captured by area rather than height, it's easy to see from them that my output is pretty much the same as usual. The only real exception is returnables, caused by me drinking more soft drink as we head into the summer. I should probably keep an eye on that.