Hobbies
Euler’s Totient Function
Euler’s totient function counts the number of positive integers up to that are relatively prime to , where is considered to be relatively prime to all . These numbers are called the totatives of . [more…]
Hobbies
Animals
Do You Like Chillies?
In the comments which nobody reads I often post photos of my parrots. In some photos I’ve posted they’re eating chillies. Some people have asked why I feed my birds hot chillies every day and [more…]
Engineering
Making A Ruby Laser – Part Two
(a ruby rod lit by two bright blue LEDs. Due to the IR filter in my camera the pink colour is actually red. What you are seeing is the absorption of the blue light and the [more…]
Arts
Postcard From the Brecon Beacons Visitor Centre
The Brecon Beacons Visitor Centre, known locally as the Mountain Centre, is not far from the village of Libanus as you drive up the A470 towards the town of Brecon. The drive up itself is [more…]
Hobbies
Solving Cryptic Crosswords – Some Hints
A Puffin asked in the comments recently if someone could do a post on this, as he had always been interested in having a go at them but didn’t know where to start. So here [more…]
Engineering
Making A Ruby Laser – Part One
Introduction For many years the Doc has had the desire to attempt the construction of a ruby laser. After six months of hard work, disappointment, late nights, lots of booze and a drained bank account [more…]
Arts
Postcard from the Algarve, No 3
Aye Aye, Puffins. It is me, El Geeko. Well, as she is over my shoulder, I should say “it’s me, and Ms Geeks”, who is keeping a furtive eye on my escapades on GPs, the [more…]
Arts
Shunting Review
Some of you who have stumbled upon this wonderful site in recent weeks and months may be wondering what various references to shunting and occasional photos of a railway scene are all about. You may [more…]
Engineering
Shunting to the end
If you remember back at the start of this series, I came up with the idea of a ‘winter project’. Well it is no longer winter, even in the North, so time to bring it [more…]