From a university student to a chief academician

Chapter 3 Ye Fei, when did you become so powerful?

After finishing the communication with Gao Fei, Ye Fei read other people's posts again.

By night, the task progress reached 60%.

Ye Fei thought to himself: "Is the setting of my mission too simple? The progress of the mission has reached 60% in half a day."

"Do you want to set the task to enter the SCI area one?"

"Fuck..." Ye Fei was taken aback by this terrible thought, what was he thinking, entering SCI Zone [-]?
Based on one's current ability, one would have to study for a long time before entering the second district.

Zhuang Nan left the computer and said gossipingly, "Ye Fei, do you know why your supervisor let your thesis enter the CSCDA area?"

"why?"

"Do you still remember the mentor's opponent, Professor Li Jiguo? I heard that one of his first-year graduate students had a paper entered the CSCDA area not long ago."

Professor Li Jiguo is also from the Department of Mathematics. He once competed with Professor Lu Yishan for the provincial scientific research fund. Both of them wanted to do scientific research and needed the scientific research fund.

However, Professor Li Jiguo failed in the competition, which led to the delay of Professor Li Jiguo's scientific research, and later competed with Professor Lu Yishan for full professor.

Because of the delay in scientific research, his scientific research had not yet been completed at that time, which led to the failure of the competition for full professor.

After this back and forth, the two of them formed a bridge.

"In addition, you are the only one of us who came up from the graduate school, and the supervisor usually has high demands on you, so naturally this glorious task will be entrusted to you." Zhuang Nan said with a smile.

"I said why did my supervisor make my thesis enter Zone A!" Ye Fei shook his head.

Ye Fei didn't doubt Zhuang Nan's information. Zhuang Nan was known as a young intelligence expert, and he could find out all the big and small things in the school as long as he was given half a day.

"Aren't you very sad?" Zhuang Nan said with a smile, "I fell into a disaster without reason."

"Not at all." Ye Fei said: "A district is A district, it's not like we can't get in."

Zhou Lin and Xu Tian walked in together with smiles on their faces, talking about their girlfriends.

Zhou Lindao: "Women, don't you come here just by beckoning to spend money?"

"Cut..." Xu Tiandao: "Are those women interested in you? Are they interested in your money? They still have to care about making a girlfriend. Women care about details."

Zhou Lin said contemptuously: "Are you out of your mind, are you out of your kidneys?"

Ye Fei and Zhuang Nan looked at the two who walked in together, and cursed in their hearts: "Two scumbags, I don't know how many girlfriends they play with."

Ye Fei is sometimes very strange, he looks quite good-looking, but he is still a novice, 100% pure new.

In terms of appearance, the entire dormitory itself is the highest.

Forget it, Zhou Lin is a rich second generation, and he is like a fish in water in the love field.

But Xu Tian, ​​from an ordinary family, is neither tall nor handsome, and a little dark, but with a mouth that can tell the dead, he has a row of ex-girlfriends.

In the end, Ye Fei concluded, it's no wonder that there are so few girls born in science, and the girls are too irrational. After being sweetly talked about, they can't find the southeast, north, south, and north.

The next day, more than 30 people were in class.

A professor in his 40s is speaking on the podium about the scalability of linear functionals on Banach spaces in the Hahn-Banach theorem in functional analysis.

This also belongs to set theory and is the axiom of choice among the five axioms of set theory.

If the continuum hypothesis is proved, then there are six axioms.

This is a very profound knowledge.

Although everyone has previewed in advance, no one in the class can understand 100%, so everyone painstakingly wrote down what the professor said on the computer.

Wait until after class to review, if you still can't learn it, you can find materials for self-study, or ask your tutor, or ask the seniors who have already learned it.

There are more than 30 people in this class, but not the graduate students under one supervisor, but the graduate students under several supervisors gathered together to attend the class.

Graduate students are very different from undergraduate students in some ways.

Graduate students are no longer talking about a certain class, but following a certain tutor.

A mentor can lead one or two graduate students every year, and lead three or four graduate students more. After three years, he can lead three to twelve graduate students.

The four in Ye Fei's dormitory followed the same mentor.

Zhuang Nan, who was sitting beside Ye Fei, asked in a low voice, "Ye Fei, seeing how seriously you listen, how much do you understand?"

"I understand everything." Ye Fei said without looking back.

In math class, you can't talk casually, and you can't bow your head. You may be dumbfounded when you say a word, bow your head, and then raise your head to listen to the teacher's lecture.

What is the teacher saying?
How to solve it here?
Fuck... I don't understand.

Zhuang Nan curled his lips and said, "Just blow it!"

Although Ye Fei came from the insurance research institute, they have been together for nearly a year, and he still knows Ye Fei's level.

Baoyan is only good at the undergraduate stage, not necessarily at the postgraduate stage.

And such a difficult course, can you understand all of it?
A smile appeared on the corner of Ye Fei's mouth. He might not understand it before, but with the blessing of the system, he really understood it.

And the degree of understanding is not 66.8%, nor 99.8%, but 100%.

Seeing Ye Fei talking to Zhuang Nan, the professor on the podium coughed lightly.

University is not as strict as junior high school and high school. As long as the classroom has little influence, the professors will turn a blind eye.

But Zhuang Nan didn't seem to notice, and told Zhou Lin and Xu Tian beside him that Ye Fei could understand everything, and both of them showed disbelieving eyes.

The professor saw that Zhuang Nan was still speaking, and everyone in the classroom was listening to the class quietly. He was still smiling when he spoke, and the nearby students were affected, which was unforgivable.

He pointed to Zhuang Nan and said, "Student, stand up."

The classroom fell silent for an instant, and everyone looked at Zhuang Nan.

Zhuang Nan looked around blankly, seeing that everyone was looking at him, he knew that what he said had offended the professor, and he panicked.

He stood up in panic.

The professor asked, "What did you just say? You said it so excitedly."

Zhuang Nan lowered his head and said guiltily, "Professor, I'm sorry."

"Tell me, what did you just say?" the professor said.

"..." Zhuang Nan was silent. It didn't matter if he was punished, but it would be bad if the other three roommates were involved, so he remained silent.

Seeing that he was silent, the professor pointed at Ye Fei and said, "The student on the right, he was the first to talk to you. What did you say?"

Ye Fei stood up and said, "Professor, he asked me how much I understood, and I said I understood everything."

"Did you understand everything?" the professor asked in surprise.

He knows the difficulty of this course. Few of the first-year graduate students can understand everything. They all study carefully after class, check the information, and learn it slowly.

Many people looked at Ye Fei in surprise.

Do you understand everything?

Don't brag, okay?

The professor laughed and said, "Since you said you understood everything, then tell me how to use the Krylov subspace method to solve linear equations."

The professor felt that this was too difficult for a graduate student, and said: "I don't want to ask for all the solutions, just give the general idea."

Ye Fei said: "Professor, can I go up? It's hard to say, I have to write it down."

Everyone looked at him in surprise, brother, you are really good!

It's easy to go up, but hard to come down!
No one believed that Ye Fei could solve the professor's problem.

"Yes!" The professor nodded.

He didn't want to embarrass Ye Fei, but Ye Fei said he understood everything, so he wanted to test it.

Just to relieve the fatigue of long-term class, just treat it as a pastime!
It doesn't matter if you can't solve it. It's normal if you can't solve it. If you can solve it, it proves that the student really understands everything.

Ye Fei stepped forward, picked up the chalk, and said to everyone: "If you want to use the Krylov subspace to solve linear equations, you can first use the Hilbert space to preprocess the Krylov subspace and its convergence."

"Consider linear algebra systems."

He tapped a set of equations on the blackboard with chalk.

【Ax=b】

"..."

"b ∈ R is a known column vector."

"That's the general idea of ​​what I think."

"Very good!" The professor nodded in satisfaction: "It seems that you really understand everything, and the idea of ​​solving the problem is very correct."

Everyone was amazed, they really understood everything, don't run into a dead mouse, you just know what the professor said!

Ye Feidao: "Actually, if you want to solve a linear algebra system, you can still solve it like this."

Ye Fei found that he had just come up to solve the problem, and the progress of the task had improved a bit.

That being the case, let's solve some problems to improve the progress of the task.

"You still have a way?" The professor was astonished.

"Yes!" Ye Fei nodded: "For solving linear algebraic systems, you can also use the projection algorithm of the Krylov subspace method."

"Do you still know the projection algorithm?" The professor was surprised.

This method is beyond the outline, and he didn't talk about it in class.

Moreover, the projection algorithm is not something learned in the first year of research, and can only be learned after the third year of research.

"I read it in a paper before." Ye Fei said, "So I learned it."

"Then you can use the projection algorithm to see."

Ye Fei turned around and wrote on the blackboard.

[Assuming that the initial solution is x, the corresponding initial residual is r=b-Ax, we call the formula

K(A,r)=span{r,ArA^2r,.Ar}
……

Here L is another m-latitude subspace, called the constrained subspace. 】

The classroom happily looked at what Ye Fei wrote, and praised: "Very good, very good, completely correct."

"Student, what's your name? Which professor's graduate student?"

There are so many people attending the class, and such a class is only once every half a month, so the professor does not know all the students present.

"My name is Ye Fei, and my advisor is Professor Lu Yishan."

"So it's Professor Lu Yishan's student, no wonder." The professor nodded and said, "Ye Fei, I remember you."

The students below looked at what Ye Fei wrote and were dumbfounded.

Fuck... I don't understand.

When did our basic mathematics major produce such a talented person?
Aren't you from Yanyi?
Are we in the same graduate school?
Zhuang Nan and the two roommates looked at each other in surprise, Ye Fei, when did you become so powerful?

"Okay, you can go down now." The professor said: "That classmate, please sit down too, and stop talking, or I will tell you to stand up."

"You also learn from the classmate next to you, and study hard."

Zhuang Nan was very worried. Who didn't study hard?I studied hard, but Ye Fei didn't know what happened today, it seemed like he was cheating.

After class was over, the three of Zhuang Nan surrounded Ye Fei, stared at him covetously, and said, "Ye Fei, tell me, did you study secretly?"

"Really not!" Ye Fei shook his head: "I just read the literature that my instructor usually lets me read, and he also recommends you to read it. If you don't read it, who is to blame."

"Really?" The three of Zhuang Nan doubted, looked at each other, and said in their hearts, "No, from today onwards, we have to read the literature recommended by the tutor."

"Let's go!" Ye Fei walked forward: "There are still classes down there!"

(End of this chapter)