universal data

Chapter 289 Visit
292 chapter

Cheng Nuo's winter vacation officially started amidst the quarrel with Mu Leng.

After a busy semester at university, Cheng Nuo finally had time to take a break.

After lying at home like a dead fish for several days, and when he was comfortable enough, Cheng Nuo had to get up again and start his study process.

"Functions of Complex Variables" and "Ordinary Differential Equations" were two courses that were needed in college mathematics competitions, and Cheng Nuo needed to complete them by himself before the new year.

After taking a taxi, Cheng Nuo went straight to the biggest bookstore in Qingcheng City.

Originally, he thought about only buying the two books of complex variable functions and ordinary differential equations, but when he thought they were all here, it was better to buy more at once. Cheng Nuo took more than a dozen books from the bookshelf and paid for them together.

"Real Variable Functions and Functional Analysis", "Abstract Algebra", "Probability Theory and Mathematical Statistics", "Topology", "Partial Differential Equations"...

These are the subjects that the mathematics department will learn during the four years of college.

He returned to his bedroom with a stack of books weighing more than ten kilograms.

The hundreds of high school review books on the bookshelf in the bedroom have been cleaned up by Jiang Lan, and it looks a little empty at the moment.Cheng Nuo put a dozen books neatly on the bookshelf and smiled slightly.

With his learning speed, it is estimated that this bookshelf will be filled again soon!
Learn it, Sao Nian!

After making a cup of coffee, Cheng Nuo sat at the desk and opened the title page of the book "Functions of Complex Variables".

In terms of difficulty, the complex variable function is naturally a higher level than the seniors and scores of the freshman.Such a course is gradually developed with derivatives and integrals as the starting point.

As a branch of function theory, compared with real variable functions, complex variable functions use the complex number field as an independent variable to perform various functional operations.

And this textbook mainly explains the content about complex variable functions through three aspects.

Analytic functions, generic maps, Riemann surfaces.

Cheng Nuo had a scrap of paper at hand, reading and calculating the theorems in the book.

For example, the Cauchy-Goursat (Cauchy-Goursat) theorem means that a function f(z) has a theorem on the region U, and g(z) is called the analytic original function of f(z) on the region U. If g( z) is analytic on U and g'(z)=f(z) holds everywhere on U.

After reading this theorem, Cheng Nuo did not directly read the proof process of the theorem below, but directly proved it on the scratch paper.

[Assume γ: [a, b]→C is a piecewise smooth curve, the parameter equation γ(t), a≤t≤b, if f(x) is continuous on γ, then ∫f(z)dz=∫( a, b) f(γ(t)γ'(t)dt,...]

After the certificate was completed, Cheng Nuo opened the textbooks and compared them.The idea is exactly the same.

wakaka!Sure enough, the great mathematician Cauchy had the same idea as me!

With a happy mood, Cheng Nuo continued to look down.

…………

After almost two days, Cheng Nuo finally finished the 200-page book "Complex Variable Functions".The content in the book has been fully integrated.Although there is still a long way to go to become a master in the field of complex variable functions, it is already enough just to deal with mathematics competitions.

Cheng Nuo was not in a hurry to study another ordinary differential equation by himself.The time agreed with Qingcheng No. [-] Middle School to hold a lecture was three days later, but today, Cheng Nuo planned to go to No. [-] Middle School to visit Lao Tang, the head teacher of the high school.

Stepping into the No. [-] Middle School campus where he had been away for half a year, Cheng Nuo felt like returning home.

Scenes from the past flashed in his mind. One year ago today, he was still an ordinary high school student, numbly accepting the six-to-nine study life, confused and at a loss for the future, and didn't know what to do in the future.But now, he is different!

His clenched fingers turned white, and his goal of becoming the king became more and more determined.

According to memory, Cheng Nuo came to the office of the mathematics team.

Open the door and enter, the office is still a familiar layout.However, after Cheng Nuo scanned around, he didn't find Old Tang's figure.

"Cheng Nuo, you're back!" Suddenly, a surprised voice attracted the attention of other math teachers in the office.

Especially when they heard the legendary name, their eyes swept across the office and finally stopped on the boy.

The teachers in the math group were half of the people who watched Cheng Nuo grow up step by step. Naturally, they were overjoyed to see Cheng Nuo.

"Cheng Nuo, did you just pass the college entrance examination and forget us old guys? It's been more than half a year, and I haven't seen you come back to see us once." The one with eyes, often asked Cheng Nuo to help Teacher Zhang, who was doing the question, turned around the seat and joked with a smile.

"No, no, I wouldn't dare." Cheng Nuo smiled wryly and waved his hands again and again, "You also know that the study at Tsinghua University is not much easier than high school. It's not that I don't want to visit, but I really can't spare the time."

"It's okay, it's okay." Another teacher in the mathematics group said, "This guy, Zhang, just thinks that you, the top student in the college entrance examination, were not taught by him, so he has a lot of resentment. You came here to find Lao Tang, right? Just give Olympiad tutoring to students in your original Class 18 classroom."

"Then teachers, I..."

"Go, go, I don't know what kind of blessings that guy Old Tang has achieved in his life to teach you such a good student." Amid Teacher Zhang's laughter and scolding, Cheng Nuo closed the door and walked out of the mathematics department office.

Since there were only 16 classes in Cheng Nuo's third grade, that is, Cheng Nuo's second grade in senior high school, the original classroom of Class 38 in senior high school became a math competition tutoring classroom.And because Lao Tang cultivated Cheng Nuo, a champion in the college entrance examination, and his own mathematics level is indeed sufficient, he became the competition tutor for this year.

After coming to the classroom door, Cheng Nuo looked in through the glass window of the back door.

There are more than [-] students sitting in the classroom, most of them are boys, and there are only a few girls here and there. They look up at the blackboard and concentrate on it.

If there is no accident, these thirty or so students will participate in the unified high school mathematics league held next year.Then the first prize winners will have the opportunity to sign up for the IMO held in March next year to win glory for the country.

Cheng Nuo had never participated in an IMO before, not even coaching a competition like this.This was a big regret for Cheng Nuo.I just don't know if there is anyone in my group of juniors who can replace him and win the gold medal in the IMO finals.

Cheng Nuo gently pushed open the back door of the classroom, touched it quietly, walked in on tiptoe, and sat down in an empty seat in the back row.

Old Tang on the podium was giving a serious lecture, but he didn't notice that there was an extra "student" in the classroom.

Old Tang was holding a competition guidance book and talking eloquently.

"Next, let's look at the last question. This is the penultimate question of the second test of the Mathematical League last year. I looked at your test paper and only Chen Gong solved it. Let me tell you about this question. ..."

(End of this chapter)