Otaku Engineer in Great Tang Dynasty

When the people of Chang'an were talking about football lively, the students of Yanhuang Academy on Yunshan Mountain outside Chang'an City finally ushered in their first class after they came to the Academy! The previous three and a half days of vacation is over!

This is also the first class after engineering was brought to the world. The significance is not insignificant. Therefore, Li Zexuan chose to teach this class in person. The location of the lecture was the auditorium that was just built shortly before the college. The architectural style of this auditorium It was designed by Li Zexuan's previous Peking University Building. This is a magnificent palace-style building. The second floor can accommodate more than 600 people at the same time. This is why Li Zexuan chose the teaching location here. The class is for all students.

More than 600 students and more than 70 teachers gathered together to make this newly built auditorium alive. Li Zexuan coughed when Mo Zhong took all the "tools" and said, "Okay, it's all quiet!" Class begins!"

The noisy classroom was silent for a moment. At present, no one in the academy dared to challenge Li Zexuan's majesty.

Li Zexuan stood on the stage, looked at the 600 students below, was silent for a moment, and said:

"From the day you decided to enter Yanhuang Academy, I believe you have already understood engineering! But that was just a brief introduction I gave in the "Datang Daily". What you learned was only literal Things, today, I will take you to see with your own eyes what real engineering is like! With all your energy and eyes wide open, you are about to enter a new world!"

Seeing Li Zexuan taking the matter so solemnly, the students raised their spirits one after another, staring at the podium without blinking, for fear that they might miss some magical phenomenon for a while. The gentlemen of the academy also looked at Li Zexuan curiously. Today they came to "listen" mainly because they wanted to learn from Li Zexuan's teaching methods. According to regulations, the academy will conduct job title evaluation at the end of the year. Who doesn't want to improve their professional title quickly?

Seeing Li Zexuan on the podium smiled unhurriedly, first he asked: "Everyone here has learned mathematics, then do you know what the ancestral rate is? Those who know raise their hands to answer!"

(Zu Chongzhi calculated the value of pi (π) to seven decimal places for the first time in the history of world mathematics. This result has led the world for nearly a thousand years. Later generations advocated calling the ratio of the circumference of the circumference to the diameter of the "Zu ratio". ", the predecessor of Pi)

As soon as the voice fell, forty or fifty students raised their hands instantly off the court.

Li Zexuan casually pointed to a thin student and said: "This student, let's talk about it! By the way, tell me what your name is!"

Although he has the ability to remember, but he hasn't taught the students of the first class before, how can he know the names of all the students?

The student was spotted by Li Zexuan, but there was no stage fright. Instead, he was a little excited. He stood up and bowed his hand to Li Zexuan and said: "Student Sun Zhongzhi, Mr. Hui's words have been recorded in "Zhushu". The ancestral rate is about three. Between one four one five nine two six to three one four one five nine 27!"

Li Zexuan nodded, and continued to ask: "Yes, then do you know how this result came out?"

The student suddenly looked embarrassed. He thought for a moment, then shook his head and said, "Uh, sir, I forgot about this..."

"Hehe, it's okay, it's already pretty good, you sit down first!"

Li Zexuan smiled and soothed, then looked at the other people and asked, "Does anyone know how the ancestral rate is calculated~?"

After being quiet for a while, a dozen or so students raised their hands. Li Zexuan pointed to Jia Jiayin, who had had several connections before, and was also the fourth place in the entrance exam of Yanhuang Academy, and said, "Jia Jiayin, come on!"

Jia Jiayin stood up and said without haste: "Mr. Hui, Liu Hui, a mathematician in the Wei and Jin dynasties, used the "circle circle technique" to calculate the ancestral rate. He first inscribed a regular hexagon from a circle, and then divided it up to the circle. Inscribed in a regular one-hundred and ninety-two polygons. He said that if the cut is thin, the loss is less, and the cut is cut again, so that it is inseparable, it will merge with the circle without losing anything. Based on his The method, Zu Shizu Chongzhi went a step further and got a more accurate result of Pi!"

(Zu Chongzhi once wrote a mathematics book "Zhushu", which records his research and achievements on Pi. But at that time, "academic cannot study its profoundness, because it was abandoned and ignored", so it was later lost. "Science" has been lost. What method did Zu Chongzhi use to calculate π to the seventh decimal place, and how to find an accurate and convenient secret rate, remained a mystery until the 21st century. But many mathematicians speculate , Zu Chongzhi is probably based on the circle cutting technique, using 12 times to cut the circle, using the inscribed circle and the circumscribed circle to approximate the circumference of the circle in both directions. A total of 14 square roots are required, and the precision of the square root should be at least a decimal point. In the last 14 places, the PI was determined to be between 3.1415926 and 3.1415927)

Li Zexuan smiled inexplicably, and continued to ask: "Then do you have other ways to get the ancestral rate?"

In an instant, Jia Jiayin, known as a child prodigy, was also stumped.

"Students don't know, I hope Mr. Enlighten me!"

Li Zexuan said: "You sit down first, let's put this matter aside, and then we will make a small game together!"

After all, Li Zexuan picked up a piece of paper from the podium with black lines drawn on it (all parallel lines, and two adjacent parallel lines equidistant), and then took out a box of fine needles (fine needles). The length of is equal to half the distance of the parallel line), after all this, he raised his head and said:

"Next, every student and husband, come up and throw these pins on this piece of paper in the order of their seats. Everyone throws them once. Come up quickly! Wang Meng, start from your side!"

Everyone was at a loss, and they didn't know what trick Li Zexuan was going to play. The same was true for Wang Meng, except that he, who was sitting first in the first row, had to come up honestly since he was named.

When he came to the podium, he pulled out a thin needle from the needle box and hesitated: "Shanchang, do you throw it casually?"

"Well, just throw it casually, you can throw it with your eyes closed, as long as you kid can throw it on paper!"

Li Zexuan said with a smile.

This is originally an experiment involving probability. If everyone deliberately throws it away, it will affect the result.

Wang Meng is also a funny comparison. Listening to Li Zexuan's words, he actually closed his eyes, "shoo", the needle fell on the paper, and then he patted his **** back to his seat~www.readwn. com~ There was a burst of laughter from the students off the field.

Li Zexuan shook his head and said, "Next, continue!"

In this way, it took more than half an hour, and all the talents went up and threw the needles again.

The students and teachers who returned to their seats turned their eyes to the podium at this time, and saw Li Zexuan lowering his head as if counting something. Although they were strange in their hearts, they did not disturb them. The entire classroom was quietly dropping the needle. .

Before long, Li Zexuan raised his head. He picked up the chalk and wrote on the blackboard, saying, "I just counted the results of your needle shots. The total number of needle shots was 713 times, which intersects with the black line. A total of 227 times! The ratio of the total to the number of intersections is 3.14,096!"

Speaking of this, he deliberately paused for a moment before saying coolly: "This is the approximate value of Zurate!"

……………………

(End of this chapter)