中文说明：算术是熵的一种形式，用于无损失数据。
English Description：
arithmetic is a form of entropy used in loss-less data. Normally, a string of characters such as the words "hello there" is represented using a fixed number of bits per character, as in the code. When a string is converted to arithmetic encoding, frequently used characters will be stored with fewer bits and not-so-frequently occurring characters will be stored with more bits, resulting in fewer bits used in total. Arithmetic coding differs from other forms of entropy encoding such as huffman in that rather than separating the input into component symbols and replacing each with a code, arithmetic coding encodes the entire message into a single number .