Omnipotent Data

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In the afternoon, the grove. ┏Ⅹ④③⑨⑨┛

Cheng Nuo went to the appointment on time after class.

On a stone table used for rest in the grove, Wang Genji had already been waiting here.

Seeing Cheng Nuo coming, Wang Genji waved to him, "This way, this way."

Cheng Nuo came to the stone table and sat opposite Wang Genji.

The Grove is an off-the-beaten-path area on campus. Except for the occasional few couples who are reluctant to spend money to go out and stay in a hotel, basically few people come here.

The wind blows the leaves and makes a rattling sound.

In the quiet grove, on the stone table, Cheng Nuo and Wang Genji sat facing each other.

"Let's start." Wang Genji glanced at Cheng Nuo, took off his coat, and spoke slowly.

Cheng Nuo nodded lightly and took a deep breath, "Well, senior, come on!"

Wang Genji took out a stack of A4 papers from the schoolbag beside him.

It was his pre-printed paper. There are seven pages in total.

He handed the printed thesis to Cheng Nuo, and looked at Cheng Nuo eagerly, "Can you tell me now, which step of my thesis went wrong?"

Last night, because he kept thinking about this matter, he didn't sleep well all night.

No, this afternoon, just after lunch, he came to this small forest and waited for Cheng Nuo early.

Even if you die, you have to die to understand.

Wang Genji didn't know if his thesis could be salvaged. But at least he needs to know where he went wrong.

Cheng Nuo took the paper with a smile and shrugged, "Of course."

Cheng Nuo took out a pen from his pocket, turned to the second page of the thesis, and drew a heavy line under a formula. "Hey, this is the step. Senior, how did you get from the previous formulas to this formula?"

The formula that Cheng Nuo drew was one of the first derivations of the new solution proposed by Wang Genji.

In the paper,

Wang Genji wrote that a bck-scholes stochastic differential equation, for example: d=1

Write the pseudo-homogeneous differential equation of this stochastic differential equation, d=σdb, so

Set another equation f=ce^σb*t, and substitute the maximum value and minimum value after the first-order derivation into the pseudo-homogeneous differential equation of the original equation, and then use the Riemann integral to solve it, and finally use the ito formula Differentiate.

The key is the process of substituting the maximum value of the first-order derivative of f written by Wang Genji.

"What's the matter, is there any problem with this step?" Wang Genji looked confused.

He thought Cheng Nuo would say that the mistake he made was in the middle and latter part of the paper.

After all, the formula calculation steps in the latter part of the paper are too many and too complicated.

Wang Genji couldn't be 100% sure whether he made a mistake somewhere.

But what Cheng Nuo pointed out to him was the first few formulas in the paper.

Seeing that Wang Genji hadn't turned his head, Cheng Nuo frowned slightly, and explained patiently, "Senior, you set a f=ce^σb*t here, and then calculate the maximum and minimum values ​​of its first derivative Value substitution."

"But how can you be sure that the f you set, its first-order reciprocal, must have a maximum value or a minimum value?"

"+ and - are both possible!"

"When the maximum value of the first-order derivative is positive infinity, or the minimum value is negative infinity, the following formula cannot be established at all."

Cheng Nuo finished his judgment word by word.

Opposite Cheng Nuo, after listening to Cheng Nuo's words, Wang Genji's face turned pale.

wrong! It is indeed wrong!

In this place, he was really wrong!

When he was writing this piece, he just mentioned it in one stroke. In other words, some take it for granted.

It does not take into account that there will be no maximum and minimum values.

As a result, a small mistake caused the entire paper to collapse.

Now, more than four months of hard work have all come to naught.

Unwilling! I'm really not reconciled! !

But what can I do.

With such a big mistake in the thesis, even a major revision may not be able to save it.

It's over!

Wang Genji smiled wryly, picked up the thesis on the stone table, tore it up, and threw it into the air.

Broken pieces of paper were scattered down one after another.

Wang Genji looked like he was unlovable in his life.

Cheng Nuo looked at Wang Genji in bewilderment, "Senior, why did you tear up the paper?"

Wang Genji was taken aback, and said in a very painful tone, "Cheng Nuo, you don't need to comfort me, I've already seen it."

"Isn't it just an SCI paper, small meaning, really, small meaning."

"This paper is useless anyway, and it's meaningless to be sad. There will be opportunities in the future, and I will try my best to write a satisfactory SCI paper."

After speaking, Wang Genji got up, put on his schoolbag and was about to leave.

That back, bleak and desolate.

Cheng Nuo stopped Wang Genji, "Senior, I didn't seem to say that this paper cannot be revised!"

"What?!" Wang Genji turned around suddenly, and looked at Cheng Nuo with thick and shocked eyes, "Cheng Nuo, what did you just say?"

Cheng Nuo smiled and repeated, "Senior, your paper is actually not as bad as you think. If you change it, it should still be usable."

"Are you telling the truth?"

"Senior, I don't need to lie to you. I also calculated the simple solution of the linear stochastic differential equation proposed in your paper. In theory, this method of first finding the pseudo-homogeneous equation and then verifying the solution with variable constants The method is indeed feasible. However, in the specific calculation process, it needs to be carefully considered."

After hearing Cheng Nuo's words, the expression on Wang Genji's face quickly changed from cloudy to sunny.

It's good to be saved! It's good to be saved!

He continued to sit opposite Cheng Nuo, looked at Cheng Nuo with kind eyes, and said with a smile on his face, "Cheng Nuo, come, let's discuss it in depth."

Subconsciously, Wang Genji wanted to take out the printed paper from his schoolbag. Only then did he tragically realize that the thesis had been torn to pieces by himself.

There was no way, Wang Genji could only crawl under the stone table, trying to put the torn papers back together.

Just at this time, a cleaning aunt passed by here. He glanced in the direction of the stone table, then widened his eyes.

From her point of view, at the stone table, there were two boys, one of whom was lying under the stone table, kneeling on his knees, with his hands on the ground, and his head was blocked by the legs of the other boy. More importantly, the body of the boy lying under the stone table was still moving back and forth. The other boy leaned back slightly, with a very comfortable expression.

That picture, tsk tsk

"Are young people nowadays so open?"

Aunt cleaning feels that she is really old. Is the current social atmosphere so open?

The cleaning aunt kindly reminded the two of them and shouted loudly. "Hey, two boys, don't do any foreplay, hurry up and do it, I saw someone coming towards this place."

Cheng Nuo+Wang Genji: "???"