I am devoted to scientific research, but you want to trick me into having a love relationship?

Chapter 492 I Met a Pervert Today

Xu Qingzhou gave a cross-application problem of ordinary differential equations, partial differential equations and linear algebra.

The first part considers the second-order linear ordinary differential equation, the second part transforms the second-order ODE into a system of first-order linear equations, and the third part is the one-dimensional wave equation, which requires consideration of the connection with the eigenvalue problem of the matrix in the second part.

Step by step.

The test assesses the mastery of differential equation theory, matrix analysis and PDE solutions, and emphasizes the ability to transfer mathematical tools between different fields.

Of course, there is a small trap. In matrix exponential calculation, if the real Jordan type is used incorrectly and the imaginary part is forcibly separated, it will lead to a complex expression.

Mars read the question and stared: "Professor, is this what you mean by not difficult?"

"I think it's within your capabilities."

Xu Qingzhou shrugged.

These questions are quite difficult for sophomores, but in Xu Qingzhou's opinion, neither Sun Simin nor Mars are ordinary people.

Mars showed a look of despair and said in a resentful tone, "Professor, not everyone is as good as you."

Xu Qingzhou checked the time and said, "You have two hours to finish these questions."

"Yes." Sun Simin nodded heavily, picked up the pen and started calculating.

Mars's expression of despair froze. Seeing that Sun Simin had already started, he did not waste time and focused his attention.

Xu Qingzhou also sat down, took out the data given by Song Yao, and continued to improve the model. After a while, Carson also came out after checking the equipment operation status.

Seeing Sun Simin and Mars fighting, he didn't say anything and returned to his seat.

These two guys are quite interesting and have some abilities, so they should have no problem passing the assessment.

Time passes slowly.

Xu Qingzhou already had several manuscripts in front of him, and was thinking about how to do Fourier transform.

"Professor, I'm fine."

Sun Simin's voice rang out in the office, bringing Xu Qingzhou back to reality.

11:30.

Half an hour faster than the time Xu Qingzhou set.

On one side, Mars stared at the topic at hand like a sculpture, seemingly isolated from the outside world and unaffected.

Xu Qingzhou took the manuscript handed over by Sun Simin.

half an hour.

"Yes, Not Bad."

Xu Qingzhou nodded slightly and said with a smile: "You have passed."

Sun Simin's face, which was tense due to nervousness, finally relaxed. She patted her chest and let out a long sigh.

At this time, Mars stood up suddenly, "Professor, I'm fine too."

Xu Qingzhou took Mars' manuscript.

The same question, but two people calculated it in completely different ways.

Sun Simin first verified the uniqueness of the equation.

Using the Picard-Lindelf theorem, the coefficients of the equation are continuous functions and Lipschitz continuous, and it is proved that the existence and uniqueness of the solution are satisfied. Finally, the solution oscillates exponentially.

Mars directly solves the characteristic equation.

The former makes in-depth use of matrix diagonalization, Sturm-Liouville theory, and Fourier analysis, while the latter solves problems concisely and efficiently through basic algebraic operations and direct separation of variables.

"Congratulations, you passed too."

After a while, Xu Qingzhou nodded with satisfaction, looked at the two of them, and said, "Not bad, you both avoided the trap I set in the question."

Facts have proved that he has a good vision and these two people are both promising talents.

To be able to enter MIT, one has at least passed the threshold for ordinary people. The next step is to rely on talent. These two people are not weak either. They just need to finish reading the three books he arranged for them.

There is an 80% chance of passing.

Finally, add 20% of carefulness. "I have a list of books here. You can read it when you have time."

Xu Qingzhou handed over another manuscript, on which was written the list of books he recommended. As long as one read all of them, one would be invincible at least in his undergraduate studies.

Xu Qingzhou was about to go to the library to edit the model given by School Beauty Song. He stood up and said, "Carson, I'll leave this to you."

As the boss, just arrange the tasks.

He is of no use now.

Let Carson stay in the laboratory, and Xu Qingzhou took his computer to the library. The environment was pleasant and it was convenient to look up information. He had nothing to do here for the time being.

However, at the intersection, Xu Qingzhou stopped.

"What the hell?"

Opposite him was the old man whom Wilson had met in his office last time.

Expression.
It’s hard to describe, it’s like it’s going to eat him.

The resentment that made one's back shiver was even stronger than last time.

Xu Qingzhou shook his head and subconsciously quickened his pace. After turning a corner, the strange sight disappeared, which made him feel relieved.

"I hope this old pervert is targeting me." Xu Qingzhou felt more and more strange.

"Have to guard against it."

He muttered to himself, but he didn't feel weak at all. He was the kind of old man who could hit anyone with one punch without even blinking an eye.

Arriving at the library, Xu Qingzhou found a seat near the window and took out his computer.

【Continuous Fourier Transform (CFT): [ F(\omega)=\int_{-\infty}^{\infty} f(t) e^{-i\omega t} dt 】

“Assume that Tesla’s stock price is sampled once per second, and a total of 60 seconds of data (N=60) is collected. The goal is to detect whether there is a periodic fluctuation to trigger a short signal, and then input the 60-second price sequence (x[n]) into the DFT formula.”

Xu Qingzhou thought about it, stood up and took out the book "Algorithmic Trading and Market Making Strategies" from the bookshelf.

The book recommended by Song Yao explains in detail the implementation details of strategies such as order book analysis, liquidity hunting, and statistical arbitrage.

At 6 p.m., Xu Qingzhou packed up and went back to the laboratory, asking Carson and the others to go home first. He stayed there until 8 p.m., then checked the instruments again, closed the door and went home.

Song Yao sat cross-legged on the sofa, looking at the computer screen, thinking about how to improve the algorithm model. While thinking, she exuded a kind of cold and aloof aura that kept strangers away.

"I am back."

Xu Qingzhou walked over to see what Song Yao was struggling with.

Hidden Markov Model.

Schoolgirl Song leaned slightly to the side, hugged Xu Qingzhou's waist, and raised her head. The coldness she had just shown disappeared, replaced by a pitiful expression. "Professor Xu, I'm so tired."

"Would you like to try Xu's massage?"

Xu Qingzhou helped her tidy up the strands of hair on her forehead. The small strands looked inexplicably cute.

"Give me a hug." Song Yao shook her head.

Xu Qingzhou nodded, sat down and put his arm around School Beauty Song's waist. It was extremely comfortable to snuggle on the sofa with the person he loved after a tiring day.

The second cat circled in front of the two people and found that there was no place for it, so it could only meow twice in resentment and lie down on the windowsill.

Outside the window, the dusk was thick and the bright lights of the city could be vaguely seen in the distance.

Xu Qingzhou let out a long breath, his thoughts gradually drifting away. This month he was going to develop the model of School Beauty Song. In terms of experiments, he had to at least enter the stage of industrial iteration.

What is process iteration? The precursor has been verified, and we only need to keep changing the parameters to improve the sample performance. But they currently don’t even have a complete sample.

Xu Qingzhou thought again of the old man he met at the intersection in the afternoon.

Song Yao buried her head in Xu Qingzhou's arms. Seeing that he didn't speak and seemed to be in a daze, she couldn't help asking, "What are you thinking about?"

"Perverted things."

Song Yao is about to raise her strong arm again.

"I mean, I met a pervert today."

(End of this chapter)