Xiaoxianzhuang, in the courtyard, Xu Chuan turned his head and looked at the senior sister behind him.

"Senior sister, can you eat spicy? Are there any taboos? ”

There is no need to ask the guests what to eat, just pay attention to the taboos of the guests.

"I, I can do it."

Liu Jiaxin followed behind and looked at the courtyard of Xiaoxianzhuang, a little nervous and worried: "It should be very expensive here, why don't we go back to the school cafeteria to eat?" ”

She had never been to eat in such a place, but she knew by feeling that it should be expensive.

Hearing this, Xu Chuan was a little embarrassed, and said: "How can there be a treat to eat in the school cafeteria, you go in first, I will pick the fish and come." ”

.......

After walking around the courtyard for a while, Xu Chuan picked the best and most delicious one with the eyes of eating fish for many years, asked the store to make one fish and three eats, added vegetables and soup and entered the inner hall.

"Huh? "Analysis and Research of Mathematical Modeling Contest Questions for College Students", do you want to participate in next year's College Student Modeling Competition? ”

Entering the inner hall, Xu Chuan saw a senior sister sitting in front of the window, holding a modeling textbook and reading it seriously.

Professor Zhou Hai mentioned this to him before and asked him to participate, but he refused, the previous IMO and IPHO can also be said to be for information security and to make up for regrets, but this is purely bullying to participate in the college student modeling competition, and he still wants to face it.

"Hmm."

Liu Jiaxin nodded lightly, hesitated, as if she was plucking up her own courage, and paused for a while before asking, "Can I ask you two math problems?" ”

The voice was very soft, so light that it was like a feather falling to the ground, if it weren't for Xu Chuan's hearing being quite good, he would almost not have heard it.

"Of course, you can be louder, no matter how small I am."

Xu Chuan smiled and teased, for him, he is very welcome if someone is willing to exchange books with him about mathematical and physical problems, of course, as long as it is not those bizarre 'civil science' problems.

Hearing Xu Chuan say that her voice was small, Liu Jiaxin lowered her head a little embarrassed, but then, she opened her schoolbag again and took out a notebook from it.

"Well, that's really bothering you."

Liu Jiaxin flipped through the notebook, found her own question, and handed it to Xu Chuan.

"What's the trouble with this, just ask if you have any questions in the future, but I don't necessarily have the ability to answer the mathematical knowledge of modeling."

Xu Chuan said casually, took the notebook casually, and looked at it, there are mathematical modeling problems, as well as ordinary mathematical problems, but the linear programming, the immediate process, and differential equations are the main ones.

This is also normal, these questions are all related to modeling.

"Okay, I've studied some of these topics, I can talk about my own thoughts."

"Also, did you bring a pen? I'll tell you about it. ”

After reading the title, Xu Chuan also breathed a sigh of relief, he didn't learn much about modeling, just a rough understanding, fortunately, he could understand the mathematical problems in the notebook and could solve them, otherwise it would be a shame.

"Yes, yes."

Liu Jiaxin nodded hurriedly, took out a ballpoint pen from her schoolbag and handed it to him.

Xu Chuan took the ballpoint pen, flipped to the blank page of the notebook, copied the previous first question, and then began to explain.

"This small question is an extension of the previous big question, and it is an extension of model two, which needs to describe the model dynamically."

"But don't be intimidated by the dynamic model, it sounds complicated, but it's really about building differential equation models, so that your model changes over time t, according to the second question......."

“.......”

“..... Since I need to analyze the sensitivity of rapid fluctuations, I can't simply look at the graph, so my analysis idea is to set the environment-related parameters in the differential equation to fluctuating variables, such as the humidity of the environment..... Then, the sensitivity to fluctuations in each stage was evaluated. ”

"Its differential equations can be reduced to ......"

While explaining, Xu Chuan wrote down his core understanding, judgment process, and corresponding simplified differential equations in his notebook.

The requirements for mathematical knowledge in the college modeling competition are far less high than those in the college student mathematics competition, and generally speaking, it is almost enough to master the basic mathematical knowledge necessary for modeling, such as advanced mathematics and calculus.

However, it requires more computer knowledge and mathematical algorithms, such as Monte Carlo algorithm, graph theory algorithm, data fitting, parameter estimation, interpolation and other data processing algorithms

It's not much less difficult to learn than pure math.

Because mathematical modeling is a very creative and challenging activity compared to pure mathematics, it is not possible to prescribe how various models can be built in concrete terms.

It involves two aspects, first, the transformation of practical problems into theoretical models; Second, the theoretical model is calculated and analyzed.

In terms of practicality, mathematical modeling is much higher than pure mathematics.

......

On the side, with Xu Chuan's explanation, Liu Jiaxin's eyes gradually brightened, and the shackles that stuck her in her mind quickly collapsed and collapsed with the ballpoint pen circulating in the notebook.

Occasionally, I followed Xu Chuan's explanation and asked one or two questions, and after waiting for accurate answers and affirmations, my eyes became brighter and brighter.

"I said that you little couple is really interesting, other couples come to eat with affection and love for dog food, you are good, learn math here."

Suddenly, a middle-aged woman's teasing voice with a smile sounded in the ears of the two.

She just noticed this pair of young men and women, it should be the students of Nanda opposite, the girls came in and held the books to read, the boys came in and she thought the girls were going to put down the books, but the boys also came over, and used this as a classroom library to start explaining the topic.

It's really interesting, she's been working in Xiaoxianzhuang for several years, and she's never seen anything like this today.

Hearing the voice, Xu Chuan raised his head, and saw a middle-aged woman standing at the table with a dinner plate, putting the food on the plate on the table in the same way.

On the other side, Liu Jiaxin, who heard the ridicule, turned red to the root of her ears, and her head couldn't stop lowering down, almost into her chest.

Stunned for a moment, Xu Chuan felt a little embarrassed, coughed and said, "You misunderstood, we are just classmates." ”

The middle-aged woman shook her head with a smile and didn't continue: "Your dishes are ready, please confirm." ”

The waiter left, Xu Chuan glanced at the senior sister, and said, "That, let's eat first, and I'll explain the rest of the questions to you when I go back to school." ”

........