Xu Guangqi was training in Henan before, and he said that he was unwell and wanted to resign. In fact, Xu Guangqi had no physical problems at all, but he lacked funds to train the new army in Henan, and he couldn't do anything, which made him fall into the quagmire, so Xu Guangqi wanted to withdraw from Henan and go back to Tianjin to reclaim.

It's just that he didn't expect the emperor to summon him personally, Xu Guangqi had to leave for the capital immediately, and he was still beating a drum in his heart, would the emperor investigate him for the crime of bullying the king?

At the same time, he thought that the emperor was asking about the training of the new army, which made Xu Guangqi search his stomach and prepare a lot of explanations.

It's just that I didn't expect that when Zhu Youxiao summoned Xu Guangqi in the Yangxin Palace, he didn't seem to remember the training of the new army at all, but asked him about water conservancy and agriculture.

"Your Majesty, the method of sweet potato planting, Wechen has studied for many years, and he has a lot of experience." Xu Guangqi said, Zhu Youxiao was overjoyed, he didn't expect Xu Guangqi to have a study on this thing, and hurriedly asked: "What is the yield of sweet potatoes per mu in the north?" ”

"If it is properly managed, the yield of 1,600 catties per mu is not a problem, and if it is planted on sandy soil, the yield will be much higher." Xu Guangqi replied.

Zhu Youxiao calculated that 1,600 catties in the Ming Dynasty were equivalent to almost 1,000 kilograms in later generations (600 grams a catty in the Ming Dynasty). Such a high yield made Zhu Youxiao frown, and continued to ask: "If ordinary farmers grow sweet potatoes in the north, how many catties can they produce per mu?" ”

"As long as you understand some management, it is not a problem to have a yield of more than 800 catties per mu." Xu Guangqi replied.

"Okay." Zhu Youxiao was overjoyed, and now the conditions for promoting sweet potatoes are ripe. Zhu Youxiao then asked about water conservancy, which is also an area that Xu Guangqi is good at, and said: "Your Majesty, in terms of water conservancy repair, I am very knowledgeable to act with experience, and I have a strong ability to adapt, and there are many whimsical ideas. The Taixi water conservancy is mathematically calculated, which is more accurate, and the disadvantage is that it is more rigid. Over the years, Wechen has devoted himself to the study of Taixi mathematics and can use mathematics to measure water conservancy projects. ”

Zhu Youxiao couldn't help but be shocked, Xu Guangqi actually studied mathematics! The requirements for mathematics in water conservancy are indeed relatively high. Zhu Youxiao, who came to be interested, said: "I also have a little dabbling in the way of mathematics, why don't you give me guidance or two?" ”

"This ...... That Weichen is ugly. Xu Guangqi bowed, his face full of confidence. When it comes to mathematics, China's elite culture does not attach much importance to it, and Xu Guangqi has been studying mathematics for many years, so he is naturally very confident in guiding the emperor.

The reason why the Chinese elite is not interested in mathematics is mainly that mathematics itself is based on assumptions, for example, no one can say how long a centimeter is, because the length of every centimeter in this world is different, but the error control is within a certain range.

The traditional elite culture is based on Taoist scholarship. The highest academic pursuit of Taoism is the way to become immortals. Mathematics is not used after becoming immortals, so the elite are not interested in studying this thing.

Industry or something, the elites are equally uninterested. What if you contribute to industry, you are not a dry bone after a hundred years. It is better to pursue the path of immortals, if you can become immortals, you can transcend reincarnation.

The number of techniques extended by traditional Taoism is mainly based on the rules of "Zhou Yi", and is applied to the calculation of heavenly luck, earth luck, human luck, etc., such as the basic language of computers in later generations 0 and 1, which is the rule in Zhou Yi.

There are also many formulas for traditional arithmetic, some of which are extremely complex, but the application fields are different. Shao Yong of the Song Dynasty even calculated the cycle of heavenly fortune.

Chinese Taoist scholarship is relatively thorough in the study of the laws of the universe. It's just that this kind of thing is too advanced for low-level primary industries to use this thing. When the Spring and Autumn Period was a hundred schools of thought, except for Lao Tzu Li Er, all the other schools of thought were applying the acquired nature of "Zhou Yi", which was also the reason why many crafts in the Spring and Autumn Period could not be imitated by later generations.

In the Spring and Autumn Period, a hundred schools of thought were finally burned by Qin Shi Huang, and the Han Dynasty began to govern the country with Taoist scholarship, and then with Confucian scholarship. The other schools of thought have lost the soil for their survival, and the trend of the Chinese nation's transformation into a science and technology-based society has been stifled.

Confucianism has a cultural contribution, but in terms of the promotion of productivity, the contribution is relatively low.

Xu Guangqi is a devout Catholic, which means that he has not learned about the traditional elite culture, otherwise he would not have accepted this kind of monism. However, Xu Guangqi, a talent who is interested in practical technology, is what Zhu Youxiao needs.

The literati who learned the elite culture, the Ming Dynasty grabbed a lot of them. Xu Guangqi is a pragmatist, but he is like a three-legged toad, which is not easy to find!

As for whether he believes in Catholicism or not, it doesn't matter so much to him!

"Pen and ink." Zhu Youxiao waved his hand, and Yang Guang hurriedly took out the pen and ink, and stood aside to polish the ink for the emperor. Then Zhu Youxiao and Xu Guangqi began to discuss the problem of mathematics.

Xu Guangqi learned European mathematics from missionaries, and after the Renaissance in the 16th century, elementary mathematics such as elementary algebra and trigonometry were largely complete. Now in the early 17th century, European geometry is well established.

The two had a discussion on geometry.

As a result, the more in-depth the discussion, the more shocked Xu Guangqi became. He could not have imagined that Zhu Youxiao not only knew Arabic numerals, but also had a deeper attainment in geometry than him. It's just that Xu Guangqi is a little confused and can't figure out why the nouns used by the emperor are exactly the same as the Chinese nouns and terms he translated "parallel lines", "triangles", "diagonals", "right angles", "acute angles", "obtuse angles", "similar" and so on.

These Chinese nouns and terms were repeatedly named by Xu Guangqi. Zhu Youxiao didn't know about this. However, Zhu Youxiao was a research monk before he crossed over! Higher mathematics is all playful, and Xu Guangqi is still learning European elementary mathematics at this time, which is naturally not above the same level.

"What Weichen has learned, compared with the emperor, is like the fire of a candle, and he does not dare to compare with the light of the sun and the moon." Xu Guangqi was really shocked by Zhu Youxiao's mathematics level, and bowed down convincingly. Zhu Youxiao said with a smile: "Aiqing has done a good job, I believe that now in the Ming Dynasty, there are few talents who can understand mathematics better than Aiqing." ”

Xu Guangqi immediately said: "The minister thinks that His Majesty should write a book and say that if you teach your advanced mathematics to the people, there will be talents available." ”

"Aiqing's idea is good, I'll take the time to write it out!" Zhu Youxiao's eyes lit up, and his mathematical knowledge is now crushing the height of Europeans. The biggest milestone in the progress of mathematics in Europe during this period should be the emergence of 'calculus', which can be applied in mechanical manufacturing. If Zhu Youxiao wants to develop machinery, mathematical knowledge such as calculus must be promoted. There are also things like Newtonian classical mechanics, which are also the primary systems that must be possessed for industrial development.

"However, there is no urgency in mathematics, and now I am in the north of the Ming Dynasty, and this is the most serious problem in front of me. So I set up an agricultural company to reclaim wasteland in the north. Since Aiqing is familiar with agricultural affairs and has experience in reclamation, it is better to have Aiqing preside over this reclamation matter! ”