"That big-eyed boy sitting in the first row!"

Seeing that Lin Man still didn't react, Zhang Yan next to him hurriedly shook Lin Man outside the amusement object: "Lin slowly, the teacher called you." "This guy, why is he always distracted in class.

"Ahh

Zhao Bin was stupid next to him, brother, the teacher said, "That big-eyed boy", in this classroom, you are a boy with big eyes, not calling you or whom.

Teacher Yin's reading glasses slipped down a little, and his eyes looked at Lin Man seriously through the upper edge of the frame: "You stand up and sober up first." The boy next to you, yes, it's you, you answer, how to write the Taylor series of this polynomial. “

Zhao Bin was shocked and stood up in a panic. I didn't expect it, I just smiled, why did I lie down and shoot. If I had known that the first row was such a dangerous area, I wouldn't have been killed.

However, Zhao Bin was still a little clever, and he replied with a bitter face: "Teacher, I'm wondering, you said, it's a good function, why does Taylor make the calculation so complicated, just calculate it directly." “

"Haha......" The audience was full of laughter from classmates.

But he also spoke up to most of his classmates. With such a complicated form, it's hard to memorize formulas during the exam.

Teacher Yin said, "Your question is very good, pay attention to the lecture, which student will answer his question?"

With the scanning of her reading glasses, all the students who whispered and made small movements immediately sat upright, and the audience was silent, not even coughing.

"The male classmate on the side, the panda-eyed one, you can answer. Everyone laughed.

"......" Prince Jin stood up stupidly, and he enjoyed the gentleness in front of him, and he didn't listen to the lecture at all. Qin Yourong won't either. The classmates next to him won't even prompt him.

"Pay attention. Teacher Yin didn't say anything to let him sit down and continue scanning.

Lin Man saw that his reading glasses were scanned on his body, so he had to say, "Teacher, I'll answer." ”

"You first come up and write the Taylor series expansion of this function. For this kind of student who is not good at studying and affects the class of female classmates, Teacher Yin's years of teaching experience told her that she must be treated at one time.

Lin Man came to the stage and confidently pinched half a piece of white chalk with his left hand. The whole piece of chalk is easy to break when writing. The children in the audience were afraid to go on stage to solve problems, but Teacher Lin Man was not afraid. I have been teaching and educating people for many years.

The title, small case, chalk words, but it is a big case.

There is no projection, no slide projection, only 4 lifting blackboards, this is the teaching condition of Teacher Yin of Mathematics. She is at most 1.5 meters tall and can't reach the top of the blackboard on tiptoe. Therefore, she needs to carefully plan how to arrange the board books, how big the characters are, where to place each question, how much space to occupy, and where she can go, they are all neatly written all over the board books, and only a long strip is left above each blackboard. Lin Man is in awe of such a neat board book, and he has great respect for such old teachers and peers who have been teaching students the basic knowledge for decades in the teaching team.

In the solution reserved by Mr. Yin, Lin Man carefully wrote down the first symbol with his left hand.

The writing was crooked, erased and rewritten.

A bunch of children whispered at the bottom.

The writing was too big, and the space was not enough, so I wiped it and rewrote it.

The voice was louder below, until Teacher Yin said solemnly, "Keep quiet." ”

"Why don't you write with your right hand?" Teacher Yin saw that Lin Man was secretly wiping his sweat with his left hand, and the chalk ash was stained on his forehead.

Well, my left hand really can't write chalk words. Chalk words, it's not an overnight effort, don't believe you try it. Lin Man changed his right hand to pinch the chalk, and just thought about tapping it in his heart, and with a "poof", the chalk turned into powder. Changing the chalk again, another ball of powder flew out of Lin Man's hand.

Some of my classmates laughed out loud. Look at the nervous look he looks. Make you usually crazy, be cleaned up by the teacher, you deserve to be ugly.

Lin Man turned his head, wanting to see which one of the non-long-eyed dared to laugh at himself, and cut him later, but he saw two pairs of bright eyes in the first row looking at him, one sympathizing and the other encouraging, neither of them laughed at himself.

Lin Man suddenly felt that everything was quiet. Control the power of the three fingers of your right hand, relax, relax. "Jiuyang Zhenjing" said well, "He is strong by him, the breeze blows the hills; he is horizontal by him, and the bright moon shines on the river." Since you can't control the power of your fingers, let him be. When his fingers were about to touch the chalk, Lin Man felt that he could already pick up the chalk. Sure enough, although I didn't really touch chalk, I was able to start writing. It looks like it's pinching the chalk, but it's actually still hanging in the air. Lin Man's mind moved slightly, and a beautiful symbol appeared on the blackboard, and then a string of symbols began to be written one by one, from slow to normal writing speed.

The problem is not difficult, as long as the formula of the Taylor series is dead.

After writing, Lin Man leaned sideways to admire his board book. Beautiful, absolutely beautiful. I have never written such beautiful Chinese characters and letters in my life.

Teacher Yin is also appreciating. The font is clean and beautiful, the math looks as smooth as water, the size is moderate, and the layout is reasonable. It was like a flash of lightning that illuminated the entire blackboard. The decades of writing skills that I am proud of have actually been covered by this student.

"Good, very good, very good. The thinking of mathematicians obviously does not provide enough words of praise, "The previous student's question, why write functions or polynomials in the form of series, you can explain." ”

"Okay, let me first explain Zhao Bin's first question. He said that Taylor's formula complicates calculations, and in my opinion, on the contrary, simplifies complex calculations. After overcoming the difficulty of writing, Lin Man was full of energy and talked eloquently.

"Pang Tong. "Teacher Lin Man has completely entered the role and has begun to master the classroom. Although he is not a math teacher, he is a computer teacher. A large number of computer problems, at the end of the day, are math problems.

"To!" The fat bucket in the last row stood up violently, and the word "to" replied magnificently. The boss has called, and he must respond. But he was muttering in his heart, Boss, if you ask me how to find derivatives, I will, but don't let me help you find points and series.

"A problem can be made with integrals, and it can also be made by summing, what method do you choose?"

"Of course, I choose addition. ”

"Why?"

"I don't know how to integrate the more complicated ones. ”

Classmates laughed.

Lin Man praised seriously: "Very good, please take a seat." If you find that you can't solve a problem with multiple integrals during the exam, but you can solve it with multiple additions in a row, will you choose addition?"

The classmates stopped laughing.

"Tao Xiaoman. ”

The dark-skinned scholar who refused to lend Zhao Bin his homework stood up.

"How do you calculate pi exactly?"

"Huh?"

"Ah, what, aren't you a scholar? The ancients would approximate pi, don't you know how to calculate accurately?"

"I won't. Xueba lowered his head, feeling that he had learned mathematics for so many years.

"Don't laugh, whoever will raise their hand. ”

No one raised their hand.

"Li Xiuli, if you can't calculate exactly, but you can approximate the calculation, will you choose approximate calculation?" When asking questions, it is also skillful to choose students, and you can't always choose students who can't, so no one will cheer you on.

"Yes. But how do I know how big the error is in the calculation?" Li Xiuli was very happy to cooperate with Lin Man.

Actually, Teacher Lin Man really wanted to name Zhang Yan. But after thinking about it seriously, I gave up.

"Very good, you are very talented. For a smart girl like Li Xiuli, Teacher Lin Man will never hesitate to praise her.

After the foreshadowing was done and the students' attention was attracted, Mr. Lin Man began to explain the meaning of Taylor's formula to simplify complex operations by addition, the meaning of estimating approximations, and the basic idea of using the remainder term to control errors.

The sentient beings looked like they had suddenly realized.

Of course, Mr. Lin Man didn't plan to let go of his best friend: "Zhao Bin, have you learned Basic Linguistics?"

"I learned. Zhao Bin didn't understand what else this programming could have to do with series.

"What other programming languages have you learned?"

"No, that's it. "Just this one, Zhao Bin has learned very painfully, and it is too difficult to debug the program on the computer.

In the early 90s, C had not yet entered the classrooms of non-computer science students, and even computer science students were still learning Pascal as a basic programming language. Assembly, Fortran, and Basic are common programming languages for general engineering students.

"Okay, how do you write a program in Basic to calculate the value of the sin function?"

"I don't, I look up the trigonometric function value in the table. ”

"What if you use the Taylor series expansion to find the value of sin(x)?" Lin Man patiently inspired.

"It's very simple, addition, subtraction, multiplication, division, plus the cycle and you're done. ”

The Taylor expansion of sin(x) is written on the blackboard, and the clever Zhao Bin certainly knows what to do.

Mr. Lin Man also introduced the application of Taylor series in programming.

Beings now understand that the Taylor series is like a universal calculation tool.

The perennial professional habits made Mr. Lin Man suddenly feel something: "That's all for today's class." Assignments are questions 3, 6, and 7 of this chapter, and they should be submitted by next Wednesday. Kids, get out of class. ”

As soon as the words fell, the bell rang for the end of class.

The students are sluggish, and Teacher Yin is sluggish......

"Shouldn't there be applause here?" Mr. Lin Man prompted.

Only then did everyone react and give sincere and warm applause. A few classmates who usually play more with Lin Man even gave a loud whistle. Except for one person.

This is a warm mathematics class, a victorious mathematics class, under the teaching of Mr. Lin Man, the students held high the banner of Taylor's formula to build a harmonious and beautiful new classroom.

A sense of accomplishment. Look at those young, enthusiastic, adoring eyes.

That's not all you need to be a teacher?

Don't worship my brother, my brother is just a teacher, a glorious teacher of the people.

Teacher Yin confirmed in time that the homework assigned by Teacher Lin Man was what she was going to assign. Class is now officially over.

Just when Lin Man was hesitant and ready to leave, Teacher Yin shouted, "Big-eyed classmate, wait a minute." ”

Lin Man was taken aback, he wouldn't find out that he was here to skip class, right?

Teacher Yin kindly asked, "What's your name?"