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Showing posts from April, 2020

Method on Buddhist's Diamond

I don't why translating this to English feels harder than translating to Japanese. Here I am and I updated this article with some new revelations unknown when I wrote the Chinese version, and got rid of some false conclusions.   Introduction BD consists of 33 familiars that fires lasers, random star bullets, and a series of aimed arrow heads from Kaguya. The interval of which the lasers are fired is actually not constant, the first two lasers are 200 frames apart, the later ones are 180 frames apart. The first aimed bullets is spawned 128 frames after the first laser, and is fired every 144 frames afterwards. The arrow heads fly very slowly, and the next wave is spawned before the previous wave leaves the screen. Similarly for lasers, the next wave start to appear before the previous wave fades off. We can model the laser, starting from the second wave by: \(\sin\left(\frac{\pi}{180}\left(x-200\right)\right)=0\left\{x>199\right\}\) aimed arrow heads: \(\sin\left(\frac{\pi...

Arch on Rpi 4 - optimization and overlay fs

So I searched for some solutions in order to avoid wearing out the sd card too quickly . Raspbian seems to have overlayfs built into the raspi-config. For Arch Linux however, the solution seems more complicated since not many people uses Arch on a arm device. https://github.com/ghollingworth/overlayfs https://github.com/nils-werner/raspi-overlayroot https://github.com/bluerider/liveroot Three projects were found and the third oneseems to be noteworthy and mentioned here . Unfortunately the author Bluerider has not been active for a quite long time and liveroot lacks decent documentation. Some discussions were found here where on the third page someone did a somewhat detailed guide on how to install it (If someone is actually trying to follow this, I would suggest you to first read every thing in that forum discussion). I used a different method which seems to work fine, although several questions remained open as I do not have a decent amount of knowledge of how these file sy...

Install Arch Linux on Raspberry Pi 4

Why don't just install Raspbian the officially supported linux distribution for Raspberry Pi? Because I don't want to (although it is the only system that can update the firmware of Rpi 4). The installation media can be obtained from here , however before following the last step to populate the arch package signing keys, I followed these steps (I am not sure if they are necessary). By default the system would turn down the wifi interface due to regulatory domain. Edit /etc/conf.d/wireless-regdom and uncomment the corresponding line would make wireless network work properly ( source ). Wifi can be configured with wifi-menu. However, for more complicated setup like eduroam, manually creating a wpa_supplicant.conf is required (see this ). Sadly the official eduroam CAT only creates a profile for Network Manager, which arch does not use by default and is a GUI tool. wifi-menu will create a netctl profile automatically, you can check under /etc/netctl/ and use netctl is-e...