Li Chunfeng was so fascinated that he couldn't help but pick up the white paper on the desk and read it carefully.
Various criss-crossing lines on the white paper vividly outline a three-dimensional figure. Even people who don't know how to read pictures can roughly understand it.
Some ancient Indian (Indian) numbers are marked on the sides of the lines, obviously indicating the length of each position.
Originally there were some complicated drawings that allowed people to see the required measurements of length, width and height at a glance, but there were some calculation formulas on the side that Li Chunfeng couldn't understand.
Compared with the plan drawings generally used in the Tang Dynasty, this three-dimensional drawing and labeling method is both convenient and intuitive.
If it is used in large-scale projects or palace construction, wouldn't it make the supervisors clearer and be able to follow the dimensions step by step in an orderly manner?
In this way, there will be no duplication of work and less error-prone.
The more Li Chunfeng thought about it, the more interesting it became, and his thoughts gradually wandered away.
Even though Li Chunfeng prides himself on being a scholar and knowledgeable person, it is still a bit difficult to look at these ancient Indian numbers.
Especially some of the formulas on the side that he had never seen before.
For example, there were some symbols +-ⅹ÷, which confused him.
Although it is a bit confusing, it seems to be so convenient.
After looking at it for a while, Li Chunfeng asked with confusion on his face: "Uncle Zhongyi, this drawing looks clear and intuitive. What do the units marked with ancient Indian numerals and the symbols next to them represent?"
It seemed that the drawings were easy to understand, but the numbers marked on them made him a little confused.
This is the drawing of the fire kang. If it is built according to the measurement of "minutes", it is too small. If it is built according to the measurement of "inches", it is too big.
Only then did Yang Fan realize that the units of measurement in the Tang Dynasty were different from those in later generations. The markings on the paper were of course in centimeters due to custom.
Because there were five main measurement units of length in the Tang Dynasty, namely minutes, inches, feet, feet, and feet. Today, there is no measurement unit like centimeters at all.
If converted, one inch is equal to about 3.33 centimeters. It's no wonder that Li Chunfeng is a little confused about the unit of measurement.
What surprised Yang Fan even more was that Li Chunfeng actually called Arabic numerals ancient Indian numerals, which made it difficult for him to understand.
But how did Yang Fan know that Arabic numerals were actually invented by ancient Indians.
In ancient India, it was necessary to calculate the movements of the sun, moon and stars for city construction and sacrifices, so mathematical calculations came into being.
Around 3000 BC, the inhabitants of the Indus Valley were more advanced in their numbers and adopted decimal calculation methods.
A set of numbers from "1" to "0" tends to be complete.
Ancient Indian numerals first spread to Sri Lanka, Myanmar, Cambodia and other neighboring countries of India.
From the seventh to eighth centuries AD, the Arab Empire rose across Asia, Africa, and Europe.
While the Arab Empire was expanding to all directions, the Arabs also widely absorbed the advanced culture of ancient Greece, Rome, India and other countries.
As the years went by, by the 14th century, Chinese printing technology was spread to Europe, which accelerated the promotion and application of Indian numerals in Europe.
Westerners accepted the Indian numerals transmitted from Arabia, but they ignored the ancient Indians at that time and only considered them to be the achievements of the Arabs, so they called them Arabic numerals.
This wrong name has been passed down to later generations, so Yang Fan didn't know the origin of the Arabic numerals.
In fact, Arabic numerals were actually called ancient Indian numerals during the Tang Dynasty, and their popularity was extremely low.
Yang Fan was still a little surprised that Li Chunfeng could understand Arabic numerals. This Taoist priest was quite knowledgeable.
However, Yang Fan was also afraid of exposing his secrets in front of Li Chunfeng and accidentally cheating himself, so the unit of centimeters was certainly difficult to explain.
After all, this is a unit of measurement for later generations.
The calculation formulas next to it, including addition, subtraction, multiplication and division, are all about calculating volume, so I can talk about it.
Looking at Li Chunfeng's eyes full of curiosity, Yang Fan couldn't bear to refuse, and besides, he might have to ask this awesome guy something later.
Thinking of this, Yang Fan explained: "Actually, I learned this from a wandering Taoist when I was young, but he called these numbers Arabic numerals. These formulas are to assist calculations, and the length measurement units are also different, like this...
"
Li Chunfeng listened carefully and had no doubt that it existed.
In fact, Li Chunfeng didn't care what the number was called or what the unit of measurement was. He was more interested in the calculation formulas.
Although I can't understand it, I always think it's very powerful.
"Is this why Uncle Zhongyi was able to answer Xu Zhang's question casually last time? Can he teach it to the poor Taoist?" Li Chunfeng pointed to the formulas of addition, subtraction, multiplication and division, his eyes flashed, and he asked excitedly
.
Helpless, Yang Fan had no choice but to bite the bullet and explain the ten Arabic numerals and the simple arithmetic of addition, subtraction, multiplication and division.
Li Chunfeng listened attentively for a long time, sometimes frowning and sometimes thinking deeply.
Finally, he shook his head and said: "This number coupled with such an algorithm is quite novel, but it is nothing more than that. It is not better than our algorithm. So how did you quickly calculate the mixed cargo of ox carts and horse carriages in Wangyue Tower?"
That question?"
Of course Yang Fan knew what issue Li Chunfeng was talking about.
When I competed with Xu Zhang, I heard Xu Zhang say that he also asked Li Chunfeng for advice on this question.
However, these calculations on paper are formulas for volume, and that time involves a linear equation of two variables, which is of course different.
Send Buddha to the West!
Yang Fan had no choice but to recite the multiplication formula to Li Chunfeng and explain the method of using a linear equation of two variables.
As the saying goes, one thing can lead to everything, and Li Chunfeng figured it out quickly.
As Taishi Ling, in charge of the revision of the calendar, he was actually an astronomer and geographer.
Regardless of astronomy or geography, it needs to be combined with a large amount of data operations.
From ancient times to the present, astronomical geographers must themselves be masters of arithmetic.
This is why Li Chunfeng became the leader in the arithmetic world of the Tang Dynasty.
Although the imperial examinations of the Tang Dynasty also included mathematics as a subject, in the era when Confucianism was prevalent, subjects such as mathematics, physics and chemistry were actually deviant techniques and heresy.
There is no such thing as the saying in later generations that one can study mathematics, physics and chemistry well and travel all over the world without fear.
In this era, no matter how well you learn arithmetic, you can only become an eighth- or ninth-grade official at most, so people who read are more interested in studying the Four Books and Five Classics.
In their view, studying the Four Books and Five Classics is the shortcut to promotion and wealth.
A master of arithmetic like Li Chunfeng could become a fifth-grade Taishi Ling. Not only was he highly skilled in arithmetic, but more importantly, he was an expert in the Taoist sect, and his knowledge was not bad.
After hearing the methods and formulas taught by Yang Fan, Li Chunfeng immersed himself in studying for a while, as if he was stunned.
I directly picked up the water-core pen on the desk and began to write and draw in a crooked way.
Li Chunfeng directly wrote two sets of large values, one set in traditional Chinese characters and the other set in Arabic numerals.
After a comparison, I saw that the traditional Chinese characters were too cumbersome, so I crossed them out again.
Finally, in the group of Arabic numerals, I used the multiplication formula to quickly calculate the result. Then I listed the division of two numerical values and listed the calculation formula to quickly get the result. I was pleasantly surprised.
With an exclamation, Li Chunfeng stood up solemnly and said in admiration: "It's easy to write these numbers. I didn't think much of it at first, but the more complex numbers are involved, the easier it is to calculate. This number combined with such formulas and formulas is simply amazing.
A genius idea. From now on, I will be able to worry less when calculating astronomy and other calendars. Thank you Uncle Zhongyi for teaching me. Listening to you is worth ten years of reading!"
Although he was wearing Li Chunfeng's tall hat with flying colors, Yang Fan clearly realized that he was just standing on the shoulders of the giant of civilization that has existed for thousands of years.
So he waved his hands in embarrassment: "This is all taught well by the wandering Taoist priest when I was young..."
Although Yang Fan said this, Li Chunfeng did not believe it. In his opinion, if this method had been invented before, it would have been spread to the world long ago.
However, Li Chunfeng did not delve into it. Instead, he showed more respect and then remembered the other purpose of coming here.
I saw him groping around for a while, and then took out something...