Compared with college graduation thesis, high school students' essays are still very simple. They do not need to cite a lot of literature. The knowledge involved is very simple, and the process of formula derivation is also clear. Li Xuan relied on his feelings to write down all the way, and his thoughts were smooth and without pauses.

place.

It is worth mentioning that in order to facilitate calculations, Li Xuan calculated the day length formula and set the unknown quantities to be the local latitude and the latitude of the direct sun point. In fact, considering the date and local latitude, the formula is more practical.

There is a certain relationship between the date and the direct sun point, and they can be substituted for each other in formula derivation. Li Xuan has directly substituted it before, but Li Xuan has not calculated the specific relationship.

When Li Xuan wrote his thesis, he did not neglect to consider this relationship and calculated it by the way.

From an astronomical point of view, the date and the latitude of the sun's direct point can be very accurate to every minute and every second. However, Li Xuan is just writing a small paper. There is no need to make it too complicated. Try to keep it simple and do rough calculations.

How to do it?

Based on the latitude of the direct sun point moving 23.5° on the equinox, Li Xuankou calculated that the direct sun point moved 7.8° every month.

In this way, the linear relationship between day length and date and local latitude is derived. Through the formula, knowing the latitude and date of a place, the local day length can be roughly calculated.

Perfect.

After I finished writing my thesis, it was time for self-study get out of class in the evening.

Li Xuan finished the paper, and then just converted the paper version into an electronic file. Just like that, he took a stack of draft paper home, turned on the computer and started working on it.

It took half an hour to type the text, ten minutes to edit the mathematical formula using Word's formula editor, and half an hour to use mathematical drawing software to draw the diagram and paste it on the Word document.

After finishing everything, Li Xuan looked at the complete thesis and felt quite accomplished.

"That's good."

After checking it and confirming that it was correct, Li Xuan was very satisfied and sent the paper to Zhao Dongming.

…

…

Zhao Dongming watched TV series in front of the computer after returning home.

At this time, the computer popped up a prompt box for receiving an email. The title was "Formula for calculating the length of day and night around the world." Zhao Dongming was a little stunned and couldn't help but laugh: "This kid, it's okay, he's fast enough..."

He turned off the TV series, opened his mailbox, and couldn't wait to read.

After carefully reading Li Xuan's paper, no matter the wording or proof process, I could find no faults. Zhao Dongming sighed, maybe there really is such a creature as a genius in the world.

"I have written such a paper since I was a freshman in high school. What will happen when I get to university?" Zhao Dongming suddenly looked forward to Li Xuan's future.

Looking to the future.

There is a national mathematical modeling competition for high school students, and Li Xuan can participate.

The university also has the National University Mathematical Modeling Competition, which is the largest basic subject competition in the university, with tens of thousands of college student teams participating every year.

Li Xuan can also sign up.

Li Xuan's breadth of knowledge far exceeds that of his peers, and his computing and thinking skills are also strong. He can complete very complex mathematical modeling processes. With Li Xuan's ability, joining an outstanding team, he can definitely win the first prize.

of.

These results will be recorded in the file, which is of positive significance for selecting scholarships and direct admission to graduate students without examination.

As a high school mathematics teacher, he could not keep up with Li Xuan's pace. He could only watch from a distance as Li Xuan strode forward, walked out on a broad road, and completed the dream he wanted to complete when he was young.

Now.

For Li Xuan's first paper, Zhao Dongming chose the mathematics magazine "The Beauty of Mathematics" to submit it. He himself felt that Li Xuan's paper was well written, very good, and the possibility of being accepted was very high.

Thinking this way makes me happy for Li Xuan.

Having never taught such an outstanding student, Zhao Dongming found that he could not teach Li Xuan anything at all. He could only shout 666 behind him. The joke turned out to be true, and he felt an indescribable feeling in his heart.

No matter what, after the paper is published, he must keep a copy.

…

…

On the other side, Li Xuan finished his thesis, took a shower and was about to go to bed, but unexpectedly received a text message from an unknown number: "Li Xuan Li Xuan Li Xuan Li Xuan..."

Li Xuan was a little surprised. Not many people knew his mobile phone number, so he couldn't help but ask: "Who are you?"

"Have you forgotten Mr. Dong by the West Lake that summer?"

Li Xuan: "..."

"Okay, I'm not joking with you. I'll tell you the truth. I'm Xu Lingchu's good sister. My name is Dong Lanyu. We met at the school gate last time it rained. Don't worry about how I got your mobile phone number."

Li Xuan remembered the experience at the school gate on a rainy day last time. It was still vivid in his mind at this moment, and he understood that it was that girl. Immediately, he felt helpless to complain. Can he finish what he said in one go, so that texting does not cost money?

"What's the matter?"

"Li Xuan, are you dating Xu Lingchu?" Dong Lanyu texted.

Li Xuan was stunned for a moment, then replied with a chuckle: "Yes, yes."

Although the relationship has not been officially confirmed yet, Li Xuan thinks it is.

Dong Lanyu sent a text message and wrote: "That's good, that's it. Don't tell Lingchu, let me tell you something. Lingchu especially wanted to perform an English drama at the English Festival because she felt that she wouldn't be able to do it if she didn't perform on stage in high school.

Complete.”

"But now, we can't find anyone to be with in the class. We are isolated by the girls in our class. She doesn't want to perform with other boys besides you. Can you think of a way?"

Li Xuan was very doubtful about the authenticity of the content of this text message. Dong Lanyu seemed to be wilted and wilted.

But he was still thinking about it while lying in bed.

How is Lingchu feeling now? Is she unhappy? He doesn't want her to be unhappy.

Is he going to do something?

…

…

The next morning, before dawn, Li Xuan got up early, washed up, and went out of the house to Xu Lingchu's house.

Because winter is coming soon, it gets very late and the surroundings are a little dark.

It's six o'clock now, everyone has not gotten up yet, the streets are empty and extremely quiet. Only the street lights are on in this street, and of course there are scattered stars in the sky.

Li Xuan took a breath and sent Xu Lingchu a text message.

"Lingchu, have you gotten up?"

After Li Xuan finished sending the text message, he was a little nervous. He was not sure whether Xu Lingchu had gotten up yet, but she seemed to always get up very early, and he received her message soon:

"I'm up...well, I'm so hungry."

Li Xuan looked at the phone and chuckled. He brought breakfast, "I'm at your door, you sneak out."

"ah?"

Unexpectedly, Xu Lingchu opened the window on the second floor and saw Li Xuan downstairs, and laughed happily.

It's like this, her mood will be affected by Li Xuan. When she sees Li Xuan being praised by the principal, she is especially happy for Li Xuan. She will also be very happy when Li Xuan appears in her sight.

…

…

Early in the morning, the two of them came to the school all the way and sat on the rooftop of the teaching building, overlooking the city and chatting in the wind.

"Everyone's understanding seems to be that music is the food of youth, relying on a pretty face. I really don't know why everyone thinks this way." Xu Lingchu said in a low voice.

"Isn't it?" Li Xuan was surprised.

Xu Lingchu beat him and laughed angrily: "Idiot, no, ability is the most important!"

"Okay, I'm just joking." Li Xuan stopped joking, suddenly his expression became serious, and he said somewhat seriously, "Lingchu, actually I planned to give you a gift this morning."

Xu Lingchu was slightly startled, biting his lip, looking forward to it, "What?"

Li Xuan said mysteriously, "My gift is a little special. I can't give it to you now. It will appear on time at 6:33:52."

Xu Lingchu rolled his eyes, curious.

Time passes.

The time is up. Li Xuan looked at his watch and suddenly said:

"Okay, the countdown begins, look at the sky."

"three."

"two."

"one."

"My gift, rise!"

As Li Xuan finished the countdown, the red sun popped up on the horizon on time, and the whole city was instantly dyed with color.

Li Xuan's words seemed to have magic power, telling the sun to rise, the sun would rise.

Just give her a sunrise like this.
To be continued...