Greetings, Mister Principal

On the third floor of the teaching tower, in classroom 301, Reiner was sitting on a chair. He had several drawings on his hand.

Claire was sitting a little farther away. She didn't know why Reiner needed her here. Although she heard that it was to assist in experiments, it was just an ordinary classroom. It was used to teach the history of magic and the like. Where was there room for experimentation?

And Reiner had just won the Hohenheim Golden Cup, did he have new discoveries again?

With many doubts in her mind, Claire saw a girl who looked timidly at the door of the classroom. She didn't seem to dare to step into the classroom.

"Dana?"

Claire recognized the student, who was Dana Christine whom Reiner mentioned yesterday.

"Uh, Professor Claire."

Dana walked in cautiously. She looked at Claire, then at Reiner, and said in a soft voice.

"I just came over to take a look, and if there is something wrong, I will leave immediately."

"It's okay."

Reiner was not surprised, because he knew that Dana would definitely come.

"Now that everyone is there, let's start."

Clapping his hands, he came to the podium, facing the two sitting down, it seemed that Reiner was the teacher today.

"Wait, you haven't said what you are going to do today?"

Claire raised her hand and asked, with a bit of complaint, because it seemed that Dana knew something.

"Mhm, I want to improve the spell model a bit, to be precise, the way to interpret the spell model."

Reiner said lightly, then turned around and started to draw something on the blackboard with chalk.

But the words of him stunned Claire and Dana.

Improved spell model? ？ ？

The spell model used now had been determined after countless practices and had reached perfection, but Reiner said that he wanted to improve the spell model?

If he hadn't won the Hohenheim Golden Cup Award, Claire would've thought that Reiner was teasing her.

Dana was silent. She watched Reiner draw a familiar pattern on the blackboard, which was a magic model of illumination.

Zero-ring spells were constructed on a plane, and all spell nodes were located on that plane, which was quite simple.

The five magic nodes and the seven magic channels connected to them constituted the basic model of this spell. The magic channels had three curves and four straight lines, and it seemed that there was no law to follow.

Seeing this magic model, Dana bit her lower lip lightly and pinched the corner of her clothes with her hands, seeming to recall some bad memories.

This was the spell she failed to cast yesterday.

"This spell model is a model of illumination. The deviation of the relative position of the node and the magic channel will cause the spell to fail. Of course, lack of magic energy will also cause similar failure."

Reiner had checked Dana's magic energy test document, and her magic energy was not inadequate, on the contrary, it was a little higher than ordinary people. Therefore, the main reason for the failure of casting spells should be her mistake in constructing the spell model.

"Miss Dana, I want to ask how you built the spell model?"

Hearing Reiner's question, Dana hesitated for a while before speaking.

"First construct the Loire coordinate system to calculate the coordinates of each node, and then establish the functional equation of the magic channel..."

The Loire coordinate system that she said was proposed by the late mage of the law, His Excellency Andre Loire two hundred years ago. It was a mathematical tool used to describe the model of spells. It was similar to the Cartesian coordinate system on the earth.

On the plane, such a coordinate system could clearly mark the position of each magic node, which was accurate and practical. By changing the position of the coordinate origin, it could also adapt to different situations.

"Is it like this?"

After listening to Dana's words, Reiner established coordinates on the spell model and marked the locations of each spell node.

Then, he began to write the functional equation of the magic channel, which was also a concept proposed by His Excellency Andre Loire. It was a mathematical expression describing the correlation between a variable and another variable. Previously, Reiner and Antoine had also used a functional equation to set up their magic signature.

However, compared to the magic node, the function equation of the magic channel of the illumination magic was obviously much more complicated. Because of the curve, the expression was very cumbersome and the amount of calculation was also large.

Seeing the familiar formula, Dana's face showed a sign of embarrassment but still nodded.

Claire still didn't know what Reiner was doing, but she had previous experiences. She suppressed the doubts in her heart, did not speak, and concentrated on listening to Reiner's lecture.

"Dana, I think a large part of your failure to cast spells is that you had a problem building the spell model. I have an exam paper here. I hope you can finish it in half an hour."

Reiner pulled out a handwritten test paper and handed it to Dana.

The student took the test paper, and her face quickly became pale.

Because all of them were math problems.

From basic calculations to complex function equations, there were ten questions on this test paper, roughly equivalent to the level of high school students on earth.

Dana glanced at Reiner, her eyes were seemingly resentful.

Nevertheless, she still picked up the quill on the table and started to work on the question.

"So now we are waiting for her to finish?"

Claire asked in a low voice, and Reiner shrugged, then handed Claire a piece of paper.

"You want to try it too?"

The question on it was exactly the same as Dana's.

"Hmph, I won't be fooled."

The same trick wouldn't work twice, and Claire was naturally not afraid of Reiner's provocation.

But curiosity still prompted her to look at the question on the test paper. When she saw the first question, her face darkened.

In the triangle abc, given that ab=2, ac=3, and angle a=60 degrees, find the length of bc and the value of sin2c.

"......"

"It's okay, you don't need to feel embarrassed if you can't do it."

Reiner chuckled. To tell the truth, this kind of question was already quite difficult for students like Dana, but the calculation of geometric relations on the plane was also necessary for a mage to build spell models.

"Huh, don't underestimate me!"

Claire glanced at Reiner, then picked up the quill and began to draft, but it was obvious that she was much faster than Dana.

Half an hour passed quickly, and both of them handed over their test papers.

Although Claire made a lot of mistakes and there were problems that she didn't know the answer to, overall she still met the standard.

As for Dana, none of the questions could be answered correctly, which made her a little frustrated.

"Sure enough, I am not suitable for being a mage."

Dana muttered to herself.

"No, Miss Dana, you just lack some basic training and more suitable methods."

Reiner's words caused the originally downcast student to slowly raise her head