Unlike Gao Shenghan and Li Junwei, who didn't even have to sleep, Yan Anke had a good night's sleep.

Before going out early the next morning, he also prepared extra things to ensure that he could stay outside all day.

BT can't track him in real time all day, and BT has no idea what he's doing outside.

Go to the classroom in advance and find a remote corner to sit down, and as time goes on, people come in and find a place to sit down.

The first class in this classroom in the morning was the other two classes, and there was still half an hour before the class, and half of the seats in the classroom were occupied, and some people were not there but put books to occupy seats.

Most of the people were memorizing words in their seats, and Yan was engrossed in studying, but they didn't feel noisy, and when the teacher walked into the classroom, it quickly fell silent.

The university is indeed a place of sixty years old, but it also depends on the situation, anyway, Nandu University, as the No.1 in Xidao Province, has countless volume kings, and it is only a minority here.

Another school has recently publicized Yan An in the school, encouraging everyone to learn from him while increasing various rewards, adding a sum of firewood to the volume kings, and even the rotten face of the tempting reward has a motivation, and one by one I can't wait to become Yan An's second immediately.

Only the voice of the teacher's speech made it easier for Yan An to enter the state of thinking about the problem, and he was a little stuck in the face of the factor factorization algorithm in front of him.

It's not easy, it's exponentially more difficult than the RSA effective search algorithm, and even if he chooses the least learned of all the factorization algorithms provided by BT, it's still a bit stuck.

If we look at the simple factor factorization of large integers, the problem of prime factor factorization can be divided into two parts, the determination of whether the given number is prime, that is, the determination of prime, and the decomposition of the large composite number into the product of prime factors, that is, the large number factorization.

As early as the nineteenth century, people on the Blue Dome had already confirmed that simple formulas for prime numbers did not exist, and Gauss considered the determination of primes to be one of the most difficult problems in number theory.

It wasn't until the invention of the Emerald computer that the efficiency of determining the nature of the equation was greatly improved by using the method of Adremann and Lumeli.

However, this is only a "qualitative" method, that is, it is simply to determine whether a number is prime or composite, and it is not possible to find all the prime factors of a composite number like trial division.

After this problem was solved, Yan An's work was much easier, but the decomposition of large numbers was not easier than the determination of prime.

If he wanted to, he could write all the mathematical knowledge involved in the process into a paper and publish it, even one of them would be enough to shake the mathematical community on this planet.

Yan An also had this kind of thought, but this kind of thing, he felt bored when he thought about it.

Even if the mathematical world here shakes a hundred times, it can't shake a single spaceship.

If studying and researching is for fame and fortune, then there is no need for BT, and he can still do it by himself.

Just as he was about to continue learning, a chalk head was thrown over, "It's okay if this classmate doesn't want to listen to the class, we will talk about the Fourier transformation in this class, you can briefly introduce it." ”

The teacher was standing only ten paces away from him, probably because he couldn't stand playing with the tablet, so he asked him to get up and answer the question.

Fourier transforms are piggyback on several sections of Fourier transformations in many science and engineering courses, such as circuit theory, signals and systems, etc.

Yan An thought for a while and said honestly: "Teacher, I am not a student in your class. ”

"Then since you came to audit, you should respect the teacher and me, you can just talk about it, let me see how much you know."

"The Fourier transform represents the ability to represent a function that satisfies certain conditions as a trigonometric function, or a linear combination of their integrals.

To put it simply, the Fourier series uses a set of orthogonal functions to represent a periodic signal, and the Fourier transform uses a set of orthogonal functions to represent a non-periodic signal, both of which transfer the signal from the time domain to the frequency domain......

When f(t) is defined between t1 and t2 and satisfies the Diliheri condition, the complex exponential form of the Fourier series can be obtained......"

If you can't dodge, then answer generously, it just so happened that he had learned this thing himself a few days ago, so he said what he had mastered.

The teacher's eyes changed from casual at first to slightly surprised later, and gradually became appreciative and approving.

The girl sitting in the first row turned to look at him, and saw the warm sunlight shining on him, and the magnetic voice disturbed people's hearts, "So handsome...... When did we have such a handsome guy in our class? ”

The subject next to her looked at her with a resentful look in his eyes, "Don't you like me, don't you want me anymore." ”

"Oh, I'm just looking, of course I love you the most!" The girl hurriedly distracted her attention to coax the object, but the eyeball never took her eyes off Yan An.

A few minutes later, the teacher saw that Yan An was going to continue talking without stopping, so he hurriedly asked him to stop.

If this continues, I am afraid that this class will be occupied by him alone.

After Yan An sat down, he ignored the few glances cast around him and concentrated on continuing his studies.

He learned the Fourier transform because of the shor algorithm used on quantum computers, the most critical of which is to use the quantum Fourier transform to find the period of f(x), and only need to obtain the period of f(x) to decompose the large integer N.

The factor factorization algorithm he is learning is different, the first step is to use the number field sieve method to construct an algebraic number field, which is the most efficient algorithm known in number theory to decompose integers, find a non-empty set of number pairs, and calculate the factor gcd of n (x-y, n).

The construction of the number field is actually the construction of the irreducible polynomial f belonging to Z[x], and f is found by the method of base m. Take r is a relatively small integer, m=[(rn)], and then express rn as m base, and choose the smaller result as f after calculation.

This is only the first step, although it is called an algorithm, but it is completely based on mathematical ideas, and the large number calculations that are difficult for the human brain to perform are replaced by computers, which contain more than one kind of mathematical tools.

It is not specifically designed to crack RSA, but exists to solve the difficult problem of integer factorization, and all algorithms that rely on it, whether it is RSA encryption or Rabin encryption, are within its attack range.

Through the first step of the number field sieve method, Yan An saw the shadow of the RSA effective search algorithm.

Previously, he had always thought that there was no progressive connection between the two algorithms, but now that he knew it, he didn't expect an explosion of inspiration, but he just figured it out and understood it more deeply.

The second step is even more unexpected, after the sieve method, elliptic curves are introduced to solve, both of which can be used separately to solve the prime factors of large integers, but it is the first time that they are used together, and Elolingjester finds commonalities between the two methods in an ingenious way.

Just as he was about to continue studying, the last bell of the morning rang, and Yan An realized that it had been so long, and he was so involved that he ignored the situation around him.

This morning's immersion allowed him to roughly learn the first step of solving the sieve method in the number domain, and he had not yet officially entered the part of elliptic curves.

He found a place to eat to fill his stomach, and while eating, he was still reading in his head, and his understanding of the number field sieve method was deeper.

After dinner, I quickly went to the library to find a remote and quiet corner to devote myself to new learning, brought in a new understanding of the logarithmic field sieve method, and reviewed what I learned in the morning, and gained more this time.

It is also the key to the next - Ye Luolin tectonic flow has achieved a smooth mastery, and officially entered the second step of elliptic curve learning.

The stage victories achieved by effective learning gave him a boost of confidence, and this taste of positive feedback made him more engaged, and the sense of accomplishment he gained in the process of solving the problem step by step was intoxicating and more motivated.

I have to admit that I wanted to acquire knowledge for purposes other than knowledge.

He wanted to go home, and even if he couldn't go back, he had to try with all his might.

However, the greatest charm of exploring knowledge is that when he comes back to his senses, the purpose of this obsession in learning is somewhat weakened.

What sprouts quietly is the love of knowledge itself.

Yan An focused on the acquisition of knowledge and forgot the passage of time, and the feeling of a flat stomach made him come back to his senses from this rare state of concentration, and he glanced at the tablet with unfinished eyes, and the content on it was tempting him to do it again.

Resisting the impulse, he looked out the window, and the setting sun slowly set and dyed half of the sky red.

It's such a beautiful view, but it seems to have forgotten something.

Yan looked at it steadily for a long time, and his hungry stomach reminded him, and he suddenly reacted to what was forgotten - hot pot!

He's going to eat hot pot today!

I almost forgot about this important thing, and hurriedly took out my mobile phone, secretly praying that my senior sister hadn't eaten yet.

It doesn't matter if you open it, just tell him where the store is.

Since he came to Nandu University, he hasn't eaten hot pot.

In the past, I would eat it once in a while, about once every two months, not for the sake of appetite, but to find a delicious hot pot restaurant, and wait until the end of December to go again, put three bowls on the table, adjust the dipping sauce, and order a table of dishes.

This is his "reunion dinner", on the day of his mother's death, he uses her favorite dish in the blue dome to tell them that he is doing well.

There is no body, no grave, he can only hope in this way, to pass on his message to them in the other world.

It's almost the end of December, and he has to hurry up and find a delicious hot pot restaurant around here.