Hawkers, it's good to let Wei Shu be quiet for a while. I was so busy all day that I couldn't find the north, who was impatient to talk nonsense with them in the student union every day? Thinking about it like this, Jiang Shuiyuan suddenly felt that his thoughts were clear and his whole body was relaxed.

Looking up at the sky, most of the club class has passed at this time, and it is estimated that even if I rush to the Kodansha of Chinese Studies, it will be time to leave the class after greeting everyone. Dragging the hall is not a good habit, Jiang Shuiyuan personally does not like this kind of behavior, and he has never put this bad behavior on others, and the next person slowly walks back to the classroom, ready to pack up and go to dinner.

As a result, when I arrived at the classroom, I saw Pu Xiaoxiang sitting in her seat alone in a daze, and she didn't know what she was thinking, but the computer in her hand was tortured by her and screamed. Jiang Shuiyuan was a little strange: "Yo, Pu Xiaoxiang, why didn't you go to participate in club activities? And I caught you, believe it or not, I will deduct your club points?"

Pu Xiaoxiang's expression suddenly became smart, and he glanced at Jiang Shuiyuan delicately: "You have the ability to deduct it! Believe it or not, I won't go home during the winter vacation, and I will move a small bench to sit at the door of your house for half a month?"

"Uh...... Count you ruthless!" Jiang Shuiyuan can be described as invincible in the difficulty of Chinese studies, but when he fought with Pu Xiaoxiang, he wanted to flee nine times out of ten. There is no way, the natural advantages of Puda beauty are too obvious, and she has the talent of a lawyer: when the facts are in her favor, she emphasizes the facts, when the reason is in her favor, she reasones, and when the facts and reason are not in her favor, she will knock on the table to muddy things. - Oh, no, as a beautiful girl from a famous family, how can she do rude actions such as "knocking on the table"? What people are best at is obviously selling cuteness and coquettishness, for example, now, she is neither angry nor angry. Just asked to move the bench to sit at the door of Jiang's house for half a month.

But does Jiang Shuiyuan dare to let her sit at his door for half a month? Not to mention ten days and half a month, even one morning, he can't stand it! His father can definitely hang him on the flagpole and do it!

Occasionally, when the threat of selling cuteness and coquettishness was ineffective, Pu Xiaoxiang would sacrifice her killer weapon "...... outside the principal's office that day". Basically, before she finished speaking, Jiang Shuiyuan was like Cixi Lafayette who was driven out of the capital by the Eight-Nation Alliance, and all his arrogance was thrown out of the clouds. Busy cutting land and paying compensation, opening up commercial ports, it is really "measuring the material resources of water sources and forming the joy of Xiaoxiang".

However, Jiang Shuiyuan was not willing to be blackmailed by Pu Xiaoxiang: "It just so happens that there is no one around now-"

"There is no one left and right, you, what do you want to do!" Pu Xiaoxiang covered his mouth with his left hand and his chest with his right hand, staring at Jiang Shuiyuan vigilantly with a look of "I'm so scared".

Jiang Shuiyuan rolled his eyes angrily: "Although I don't know what you're thinking in your head, I still want to say: Girl, you're thinking too much! Take advantage of the fact that there is no one left and right, hurry up and tell you honestly, do you also have a part in the fecal attack on the vice president of the student union at the school gate this morning?"

"How could I? someone like me who has a habit of cleanliness. You don't slander good people, I'm a woman from a good family!" Pu Xiaoxiang argued hesitantly, his big black and white eyes were spinning, and anyone who saw it knew that there must be a ghost in it.

Jiang Shuiyuan snorted coldly: "Hmph, dare to quibble, Wu Zichen has honestly explained to me!"

"How dare he! Believe it or not, I'll tear his mouth apart?" Before he finished speaking, Pu Xiaoxiang knew that he was exposed. hurriedly remedied: "I mean, Wu Zichen is talking nonsense. Slander me, so I'm going to tear his mouth apart...... No, I'm going to settle accounts with him!"

Jiang Shuiyuan looked at him with a smile: "Girl, do you think I will believe it?"

"Believe it or not!" Pu Xiaoxiang didn't dare to look at Jiang Shuiyuan again, his jade face turned his head slightly red, and his fingers crackled on the calculator again. It seems that he wants to express his strong dissatisfaction to Jiang Shuiyuan through this move.

Pu Xiaoxiang frantically pressed the cos button on the calculator, because the speed was too fast, the calculator couldn't react at all, and could only keep making the sound of "co, co, co", which sounded like "cry, cry, cry" in Chinese. It's a bit frightening in the dimly lit and slightly empty classroom. Jiang Shuiyuan didn't pay much attention to it, and when he occasionally glanced at the screen at a certain moment, he couldn't take his eyes off it.

"Let me take a look!" Jiang Shuiyuan stretched out his hand and grabbed it.

Pu Xiaoxiang saw that the claws of the Lushan Mountain of the water source of the river were grabbed directly towards his jade hand, and thought that he wanted to lighten himself, and his heart was both angry and happy: "You, what do you want to do?"

"Borrow your calculator and pay it back later. Jiang Shuiyuan said, picked up the calculator, sat back in his seat, and began to study.

Similarly, he pressed the cos button wildly, but his eyes were fixed on the screen without moving, as if he wanted to discover some shocking secret. Pu Xiaoxiang came over curiously, and the good fragrance suddenly filled the nasal cavity of Jiang Shuiyuan, and if she felt sensitive, the skin on her face seemed to be able to vaguely feel the heat she exhaled: "What are you doing?"

"Have you ever noticed that if you type a random number on the calculator and then keep pressing the cos key, the number will always tend to a fixed constant of 0.739085133......" Jiang Shuiyuan said, pointing to the screen.

Pu Xiaoxiang blinked: "I've noticed it a long time ago!" If you choose 'radian', enter a number casually, and then keep clicking the cos key, you will get the value you said; if you choose 'angle' and then enter the number casually, and keep clicking the cos key, you will get another constant, which seems to be 0.99984774......; If you select 'gradient' and then enter the number randomly, if you keep clicking the cos key, you will get a constant, which seems to be 0.99987666...... What's so strange about that? I found out when I was in elementary school!"

"Don't you think it's amazing?" Jiang Shuiyuan's eyes lit up.

"What's so magical? Anyone who has ever played with a calculator knows it. Pu Xiaoxiang rarely found an opportunity to despise Jiang Shuiyuan in his studies, and naturally he would not let it go at this time: "Classmate Shuiyuan, don't you know?"

Jiang Shuiyuan nodded honestly: "I really know, if I guess correctly, 0.739085133...... This constant should be the only real solution of the equation cos(x)=x, i.e., the fixed point of the cosine function y=cos(x). It seems that no one has ever mentioned this before, and it is worth writing a good little essay just for this. ”

What is the only real solution to an equation? What is the fixed point of the cosine function? Pu Xiaoxiang didn't understand it, but it didn't matter, she immediately grasped the core of the problem: "Writing a paper? This is the first thing I discovered, and I should be added when the paper is signed!" (To be continued......

PS: The story is true. Although this phenomenon was discovered early on, it was not until 2007 that Samuel R. Kaplan published a paper in MathematicsMagazine.