afternoon.
After eating and reading in the library for two hours, Wang Donglai got up and headed towards Yang Wanpeng's office.
This time is exactly the time when Yang Wanpeng gives guidance to students participating in the Higher Education Society Cup National Mathematical Modeling Competition.
Because Yang Wanpeng had told Wang Dong about his office before, Wang Donglai quickly found his office.
After entering, I found that there were two people already in the office.
Both are boys and there is no girl.
"Classmate, are you also participating in the mathematical modeling competition?"
One of the boys wore glasses and proactively greeted Wang Donglai.
"Well, are you too?" Wang Donglai nodded in agreement and asked the two of them.
"Liao Qingfeng, a junior in the Department of Computer Science."
"Mathematics and Applied Mathematics, junior year, Ye Fei."
The two took the initiative to reveal their majors, and Wang Donglai also told him his major class, "Qian Xuesen's mathematics experimental class, freshman, Wang Donglai."
"Are you Wang Donglai?"
"You were the one who caused such a big disturbance at the Terracotta Warriors and Horses two days ago?"
Liao Qingfeng and Ye Fei obviously didn't expect that the person who appeared in front of them would be the person who caused quite a stir on the forum.
"Um!"
Wang Donglai's expression did not change and he responded calmly.
The atmosphere became cold, but it didn't last long. Soon Yang Wanpeng opened the door and walked in.
He glanced around and saw that everyone was here, so he said aloud: "You should introduce each other. Next, the three of you will be a team. I will not arrange the specific division of labor, modeling, programming , thesis and defense, the three of you will discuss among yourselves and divide the work according to your personal strengths."
"But let me say one more thing, you three were specially selected by me. Liao Qingfeng's computer skills are pretty good, and Ye Fei's math skills are also pretty good. As for Wang Donglai, although he is only a freshman, he is no worse than you two. I have already published an SCI paper, and the content of the paper is related to mathematics and big data algorithms. It is very professional, and I am also the top scholar in the national liberal arts. I can do everything from paper writing to defense, or anything else."
After saying this, Yang Wanpeng walked to his seat and turned on the projector in the office.
"This time in the National Mathematical Modeling Contest, I hope you can do your best and come back with a first prize."
After saying this, a picture appeared on the projector.
"The above is the original question of the 2007 Mathematical Modeling Competition, National Population Growth Forecast. This question is not difficult, but it is a bit difficult to do well. The more accurate it is, the higher the difficulty. It is just for you to try. .”
As he spoke, the PPT displayed on the projector began to turn.
“Our country is a country with a large population, and the population issue has always been one of the key factors restricting our country’s development. Since the comprehensive implementation of family planning in 1973, the fertility rate has dropped rapidly and has achieved world-renowned achievements. However, the construction of a well-off society in an all-round way still faces the problem of population. Situation and severe test..."
"Please use mathematical modeling methods to analyze and predict my country's population based on existing data."
Seeing this question, Wang Donglai instantly knew the answer.
It was not entirely because he had the memory of more than ten years later, but also because of his mental arithmetic ability. At this moment, he quickly performed complex calculations on the given data and obtained the answer.
"What do you three think about this question?"
After Yang Wanpeng introduced this question, he stopped and asked the three people.
Ye Fei first glanced at Wang Donglai, with a hint of hidden arrogance in his eyes, and took the initiative to say: "I think this question is very simple. First of all, the model assumes that all factors that characterize and affect population changes are of average significance to the entire social population. Decided.”
"The levels of births and deaths are relatively stable during the forecast period, and even if there are changes, they are relatively regular."
"..."
“It is assumed that projections of future population are most likely to be consistent with future trends in population development.”
“Then, it is dimensionless. The initial value is used to transform the original data to eliminate the dimensions. The 2001 data of each indicator series of my country’s population is used to remove the subsequent original data to obtain its multiple series, which is the initial value series. Dimensionless, all greater than zero, this way the sequence has something in common, that is, the problem turns to the analysis and comparison of the growth multiples of each factor in the original data, which simplifies the processing of the problem."
"Remember that a certain sequence after initialization is the parent sequence {X0(t)}, and the remaining related factors are the subsequences {X1(t)}, that is, at time t=k, the parent sequence {X0(t)} and the subsequence The correlation coefficient of the sequence {X1(t)} is..."
"Among them, a∈[0, 1] is called the resolution coefficient. Obviously, the larger a is, the greater the resolution. For simplicity, we take a=1."
"For all points k=1, 2, A, n3, define the gray correlation between the comparison sequence X1 and the reference sequence X0 as..."
It has to be said that Ye Fei was eloquent and seemed to have a well-thought-out answer. He explained the solution to this question just by dictating it.
After roughly speaking, Ye Fei glanced at Wang Donglai before sitting down.
Yang Wanpeng was noncommittal and did not comment. Instead, he looked at Liao Qingfeng and Wang Donglai, "Do you two have any opinions?"
"There is no problem with programming, it can be realized!" Liao Qingfeng replied confidently.
"Well, I probably understand." Wang Donglai also roughly understood some modeling methods after Liao Qingfeng's answer.
Yang Wanpeng nodded, and the PPT was updated again.
"Look at past students' answers to this question, expand your thinking, and understand the key points of modeling."
The picture changes to show the answers given by past students.
Seeing the information above, Wang Donglai shook his head invisibly.
Because the data predicted above are really far different from the real situation.
In 2010, the national population was estimated to be about 1.35 billion.
In 2020, the national population is predicted to be 1.4 billion.
In 2025, the national population is predicted to be 1.42 billion.
In 2030, the national population is predicted to be 1.45 billion.
In twenty years, the population increased by 100 million.
The population is only increasing, not decreasing, as if everyone has a strong desire to have children.
However, the actual situation may be that only Wang Donglai in this world knows the real situation.
"The principle of mathematical modeling is actually very simple. It is to establish mathematical models based on actual problems, solve the mathematical models, and then solve practical problems based on the results."
"It is a kind of simulation, which is an abstract and brief depiction of the essential attributes of an actual subject using mathematical symbols, mathematical formulas, programs, graphics, etc. It may be able to explain certain objective phenomena, or it may be able to predict future development patterns. It may provide an optimal strategy or a better strategy in a certain sense to control the development of a certain phenomenon.”
“In terms of programming, there are several most commonly used software. It’s up to you which one to use. Matlab, Mathematica, Lingo, SAS. Just pick one and get familiar with it. As long as it can answer questions, even Excel will do. "
After Yang Wanpeng finished teaching the courseware, he said this to the three of them.
"Well, I have been exposed to Matlab and SAS before, and there is no problem!"
Liao Qingfeng said confidently.
"Well, next you can read more books by yourself. You can read books such as "Mathematical Model", "Mathematical Modeling Algorithm and Application", "Matlab Application in Mathematical Modeling", and "SAS Common Statistical Analysis Tutorial". "Basic Tutorial on Mathematical Modeling" can also be found.,
"Although I am your instructor, I will not give you complete guidance. It depends more on your own learning and your own abilities."
"You can also try to do the questions I asked you to take before, and practice more."
Yang Wanpeng said and packed up his things.
Seeing this, the three of them also stood up, agreed in unison, and left.
After leaving the office, Liao Qingfeng took the initiative and said to Wang Donglai: "Let's add a contact information first so that we can contact him if anything happens later."
Wang Donglai naturally would not refuse, so he exchanged contact information with Liao Qingfeng and Ye Fei.
After exchanging contact information, Liao Qingfeng took the first step, but Ye Fei suddenly said something to Wang Dong, which made Wang Donglai stunned.
