Question: I came across some super-nice interactive textbook-style website which gently introduced the Fourier transform with many intuitive and interactive graphics. It was top-notch modern, with dynamic SVGs and looked excellent.
This was about 6 months ago and I can't find the page anymore and I forgot to bookmark it.
If this rings a bell, please share the link! Thanks!
No, sorry, unfortunately I can't. Bought mine on eBay.de a few years ago. Now on eBay.com the auction format seems to be hardly used anymore for things like that. Hmm. Many direct imports though. Maybe my suggestion is outdated.
If you don't mind the process of finding something (or waiting for something to come up) on eBay too much, I recommend looking for used photo/film equipment out there.
I cheaply sourced two photo/film lamps on eBay.
One is a 500W LED lamp and somewhat blueish, the other is a 330W fluorescent, but of very high quality, it's a very convincing daylight tone (not at all greenish). Especially the latter makes for a very nice room light.
Both were barely used, yet substantially cheaper than new.
The advantage is that you can easily change their angle on one or two axes. I originally bought them for photography and then started liking them as regular room lights, only to later even realize that I basically got myself SAD lamps.