An Expert Is actually By My Side

Chapter 102 "Trouble" caused by your students

Not only Hao Yun's parents were watching the CCTV interview, but also Hao Yun's three sons in dormitory 401, plus a little chubby Zhou Xuan who always came to 401 to sleep together.

"Brother Yun is awesome! This must break the Guinness World Record for the fastest submission time in the Hope Cup competition, right?" Seeing Hao Yun walking out of the stadium, Zhou Xuan couldn't help shouting.

"Is there still this record?" Liang Ziyuan asked.

"Hey, we can apply for him." Zhou Xuan said with a shy smile.

"But what the host said... the main test committee is in a meeting, what are you talking about?" Zheng Xueqian rubbed his chin and frowned thinking.

"Ghost knows, maybe they wrote some terrible answers up here." Zhou Xuan shrugged his shoulders and said helplessly.

Great answer?

What kind of answer could this be?

Including Zhou Xuan himself who threw this sentence, everyone around the computer had curious expressions on their faces.

At the same time, Professor Li Xuesong, who was flipping through his thesis in the Mathematics Office of Jiangcheng University, suddenly received a call from Xiaguo Mathematics Research Institute.

The caller was Professor Liu Shoufeng, a master in the field of number theory in China, and also the author of the last big question in the previous college mathematics competition.

Professor Li Xuesong was too lazy to answer the caller ID on the mobile phone, but he thought that the old man was not an ordinary narrow-minded person, so he patiently pressed the button to connect.

"Hello? What's the matter, Old Liu?"

"Did you see the email I sent you?"

"mail?"

"Just sent it to you!"

Not knowing what medicine was buried in the old guy's stomach, Professor Li Xuesong opened the mailbox full of doubts, and he saw an unread email.

Hello, 1 minute before the mailing time?

It's not that there is a message on WeChat, how can the ghost see your email!

He rolled his eyes and opened the email, but Professor Li Xuesong was stunned when he saw the contents.

The text only has a string of unintelligible characters——0x5f375a86

"Is this a hexadecimal number?" Touching his chin, Professor Li Xuesong's face was full of interest, "Is there any mystery about this number?"

Every time Liu Shoufeng, an old man, calls him, there are two things, either to show off, or to share some latest discoveries. Usually he can see some clues, but he looked at this number for a long time, and even made the decimal and binary changes silently in his heart, but he didn't feel anything different.

Professor Liu Shoufeng on the other end of the phone chuckled: "Sure enough, even you can't see anything special about this number!"

"Don't be a fool, you old thing. If you have farts, let it go at once, and I'll hang up if it's okay!" Professor Li Xuesong said with a smile.

"Hang up? Then you will definitely regret it! Don't talk nonsense with you, do you remember the Newton-Raphson method?"

"Nonsense, who doesn't remember this!"

The Newton-Raphson method is a method proposed by Newton in the 17th century to approximate the solution of equations in the real and complex fields. Although this method is rarely used among those who study pure mathematics, this The method is widely used in the computer field.

For example, if you want to calculate the value of √2, first guess a random number such as 4. There is no doubt that √2 cannot be equal to 4, but as long as you use the Newton iterative method to iterate continuously, after n steps of iterative operations, you can always calculate 1.414... . And if you use 2 as the guess value, because 2 and 1.414 are close enough, it only takes two iterations to calculate it.

Li Xuesong remembers that he seems to have talked about this knowledge point more than once in class with computer majors, but he really doesn't know what is so good about this stuff.

Professor Liu Shoufeng: "I just sent you another email. There is an algorithm that has been translated into mathematical language. After reading it, you will know why I am so surprised by this number."

Hearing this sentence, Professor Li Xuesong couldn't help but rolled his eyes, but he couldn't hold back the curiosity in his heart, so he clicked on the next email as he said.

The whole algorithm itself is not difficult, but it is just to find the reciprocal of the square root. Professor Li Xuesong even feels that even if it is not translated into a language of mathematics, he can fully understand it.

Simply put, that 0x5f375a86 is a constant used to calculate the guess value.

Because using the Newton iterative algorithm to calculate the reciprocal of the square root first requires a guess value, which is usually determined through a series of calculations based on the value entered by the user.

Professor Li Xuesong made up a random number and tried to use this algorithm to find the reciprocal of the square root.

However, at this moment, something magical happened!

He found that no matter what value he entered, the guess value obtained by the system was so close to the final result that the entire algorithm only needed to be executed twice at most to end the loop.

And the reason for all this is because of that 0x5f375a86!

"Unbelievable..." Gradually discovering the mystery, Professor Li Xuesong murmured, "How did this number be discovered?"

His mind is full of questions now.

Why is it 0x5f375a86?

Professor Liu Shoufeng said in a joking tone: "I have to ask you, after all, it is the 'trouble' caused by your students."

Hearing this sentence, Professor Li Xuesong was shocked.

"My student? Are you sure?"

What the hell? !

Why didn't I know I had such an awesome student?

"That contestant named Hao Yun is not your student?" Suddenly, as if remembering something, Professor Liu Shoufeng patted his head, "Oh, I almost forgot, the one you named is the main examination committee of the mathematics competition... The Cup of Hope is for programming, so it seems that it really has nothing to do with you."

"Wait, you mean Hao Yun? Hope Cup? What do you mean?" Professor Li Xuesong asked confusedly.

Professor Liu Shoufeng explained patiently: "In short, there is a question in the Hope Cup Competition, which requires improving the operating efficiency of a piece of software. So far, your student has done it, and the solution surprised everyone. Usually The code farmer’s idea should be to start with the code, right? As a result, he went directly to modify the code of the underlying function, so that the function that originally required a few more steps to understand could be done in two steps.”

Professor Li Xuesong was stunned, and it took him a long time to hold back a word.

"...Is it so awesome?"

"Yeah, it's more than awesome. None of the old guys in the main test committee figured out what the number was, and then sent an email to our Xiaguo Mathematics Research Institute, but I didn't see it after reading it for a long time. What a hall of fame."

While talking, Professor Liu Shoufeng sighed and continued.

"This reminds me of the famous Basel problem, that damn infinite series Σ1/n. No one knows why the person who first discovered it converges to π/6 is so bored as to remember the value of π/6. You know that is an irrational number, who can memorize that? But the annoying thing is, he just knew it! And it was later proved to be true!"

"We have to admit that some people in this world are indeed very sensitive to numbers, even beyond the understanding of ordinary people, reaching the level of intuition... At least, before I chatted with your student face to face, this is all I can do now explained!"

at the same time.

Shanghai is thousands of miles away.

The reporter, who was squatting outside the lounge of the gymnasium, finally waited for the opportunity for the door to open.

Without any hesitation, she immediately caught a man in a plaid shirt coming out of the backstage.

Judging by his face and appearance, he should be a software engineer.

In this way, maybe I will know some inside information!

"Hi sir, I'm a reporter from CCTV's education column, may I interview you, what kind of answers did that contestant submit, so that the main examination committee needs to meet to discuss... Can you disclose any information? "The lady reporter asked curiously.

The man didn't want to be interviewed at first, but after seeing the logo on the microphone, with a hesitant expression on his face, he finally spoke.

"The competition is still going on, and I can't disclose too many details. As for the contestant you mentioned... What's surprising about him is that his answer can be said to have changed only one number."

"One, a number?!" The reporter was shocked.

Even the photographer behind her had a surprised expression on his face.

"Yes... I am also very surprised. It can even be said that this is completely beyond our expectations? Maybe it will affect not only the glacier engine, but also products in other fields."

When he said this, the face of the man who was probably a software engineer was half solemn and half helpless.

"In any case, this is beyond the field of my own understanding. The professors from the Department of Mathematics of Xiadong Normal University will come over in a while, and they seem to have set up a temporary expert group. You may wish to ask their opinions, maybe you can Give you a reasonable answer?"