VLESS + WS + TLS For Home IPv6 with Cloudflare DNS Proxy

The Usage of the Volume of Lead in Pencil

$\tan{\theta}={{r}\over{l}}={{\Delta r}\over{\Delta l}}$

The used volume $V_1 = {1 \over 3}\pi {{\Delta l}^{3}} \tan ^ {2} \theta$.

The removed volume $V_2 = \pi \Delta l^3 \tan ^ 2 \theta + {1 \over 3} \pi l ^ 3 \tan ^ 2 \theta - {1 \over 3} \pi \Delta l^3 \tan ^ 2 \theta - {1 \over 3} \pi l^3 \tan ^ 2 \theta \\ = {2\over 3}\pi \Delta l^3 \tan ^2 \theta$

${{\Delta V_2}\over{\Delta V_1}} = 2$

${{\Delta V_2}\over{\Delta V_1 + \Delta V_2}} = {2\over 3}$

${{\Delta V_1}\over{\Delta V_1 + \Delta V_2}} = {1\over 3}$

This shows that only $1\over 3$ of pencil is used.

Install v2ray on VPS in China Mainland

For those Chinese who often travel abroad, it would be better to have a VPN server that routes the internet traffic back to China. For example, some music or government website will reject requests outside China.

e in Python function

Here is a function written in Python. It is used to randomly choose at least one from a list.

import random
import math
def choose_at_least_one(list_items):
    chosen_items = [i for i in list_items if random.random() <= (1/len(list_items))]
    if len(chosen_items) == 0:
        return choose_at_least_one(list_items)
    else:
        return chosen_items

Mailvelope setup on Linux Mint

Unlike the easy installation process on Windows platform, on linux to make Mailvelope use GnuPG you have to follow the official instructions.