# Gilbert Strang: Linear Algebra, Teaching, and MIT OpenCourseWare | Lex Fridman Podcast #52 | Summary and Q&A

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November 25, 2019
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Lex Fridman Podcast
Gilbert Strang: Linear Algebra, Teaching, and MIT OpenCourseWare | Lex Fridman Podcast #52

## TL;DR

Gilbert Strang discusses the importance of linear algebra in mathematics and AI, shares his favorite topics in linear algebra, and reflects on the role of teaching and learning in math.

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### Q: What inspired Gilbert Strang to create the MIT OpenCourseWare lectures on linear algebra?

Strang was inspired to create these lectures to make the important subject of linear algebra accessible to a wider audience. MIT's decision to give away the course materials for free on OpenCourseWare was a groundbreaking idea.

### Q: How does linear algebra differ from calculus and other mathematical fields?

Linear algebra focuses on the relationships between matrices and vectors, while calculus deals with rates of change and curves. Linear algebra is often used to understand and analyze data, making it integral to fields such as AI and data science.

### Q: Can linear algebra be applied to practical fields like engineering and physics?

Yes, linear algebra is widely applicable in various fields. Engineers use linear algebra for tasks like analyzing structures and designing bridges, while physicists use it to study concepts like second derivatives. Linear algebra provides a framework for understanding complex systems.

### Q: What is Gilbert Strang's favorite matrix?

Strang's favorite matrix is a square matrix with twos running down the main diagonal, and -1s just above and below that diagonal. This matrix has various applications, such as representing second derivatives in calculus.

### Q: What inspired Gilbert Strang to create the MIT OpenCourseWare lectures on linear algebra?

Strang was inspired to create these lectures to make the important subject of linear algebra accessible to a wider audience. MIT's decision to give away the course materials for free on OpenCourseWare was a groundbreaking idea.

## More Insights

• Linear algebra plays a crucial role in the fields of AI and data science, providing tools to analyze and understand complex datasets.

• The availability of free online resources, such as MIT OpenCourseWare, has made education more accessible and allowed millions of students to learn from renowned professors like Gilbert Strang.

• Linear algebra offers a way to break down large matrices into simpler components, leading to a deeper understanding of the underlying data.

• The four fundamental subspaces in linear algebra (column space, row space, null space, and left null space) provide insights into the structure of matrices and their relationships.

• Deep learning, an approach used in artificial intelligence, relies on nonlinear functions to approximate complex data patterns, with linear algebra being an essential tool in defining these functions.

• While calculus and probability also play important roles in mathematics, linear algebra's relevance to data analysis and its ability to handle high-dimensional datasets give it a distinct importance in modern applications.

• Passion and inspiration are key factors in effective teaching, and a teacher's enthusiasm for their subject can spark love and interest in mathematics for students.

• Learning mathematics involves finding connections between ideas and developing an appreciation for the patterns and beauty within the subject.

Overall, Gilbert Strang's insights highlight the significance of linear algebra in mathematics and its applications in various fields, particularly AI and data science. His passion for teaching and the importance of making mathematics accessible to all learners shines through in this conversation.

## Summary

In this conversation, Gilbert Strang, a professor of mathematics at MIT and renowned teacher of math, discusses the importance and beauty of linear algebra and its applications in artificial intelligence and other fields. He also talks about the impact of his MIT opencourseware lectures on linear algebra and the power of online education. He shares insights into the nature of math and its appeal to people, as well as the role of math in politics and society. Additionally, he discusses the concept of deep learning and neural networks, explaining the role of linear algebra in these areas.

### Q: How does it feel to be one of the modern-day rock stars of mathematics?

Strang responds that while he doesn't feel like a rock star, he acknowledges the impact of his MIT opencourseware lectures on linear algebra and the surge in importance of linear algebra as a subject.

### Q: What was the idea behind putting lectures online with MIT OpenCourseWare?

Strang explains that the idea came from a committee appointed by the president of MIT, who realized that giving away the educational content for free would be the best way to showcase what MIT was really like.

### Q: Were you surprised by the result of making the lectures freely available online?

Strang admits that he was surprised by the popularity of the videos, but he believes it was the right idea and effectively showcased the importance of linear algebra and the work at MIT.

### Q: What is your favorite specific topic in linear algebra or math in general to teach?

Strang mentions the importance of teaching the concept of the four fundamental subspaces in linear algebra, as it provides a simple yet powerful understanding of matrices and their relationships.

### Q: What do you find beautiful about singular values in linear algebra?

Strang explains that singular values are a way to break down a matrix into simple pieces, allowing for a better understanding of the patterns and important components within the data.

### Q: How do you think about the things like a 10-dimensional vector that we can't really visualize?

Strang admits that he thinks in terms of three dimensions, but linear algebra allows for easy extension into higher dimensions, making it a powerful and useful tool.

### Q: Do you think it's better to think abstractly or plug in numbers when learning new concepts?

Strang suggests that starting with examples and visualization can help understand abstract concepts, but ultimately it depends on the individual's learning style.

### Q: Have you seen moments of learning in students' eyes that indicate a connection with math?

Strang believes that there are moments when students understand and appreciate the beauty of math, even if they struggle with exams or evaluations.

### Q: What advice do you have for someone just starting their journey in mathematics?

Strang advises finding a teacher or professor who is passionate about the subject and enjoys teaching, as their enthusiasm can make learning math more enjoyable.

### Q: How does linear algebra compare to calculus and probability/statistics in terms of importance and teaching emphasis?

Strang believes that linear algebra is often overlooked in favor of calculus, but linear algebra has become increasingly important, especially in data science and artificial intelligence.

### Q: What is your favorite matrix?

Strang's favorite matrix is one with twos running down the main diagonal and minus ones just above and below, as it has many applications in engineering and mathematics.

## Takeaways

Gilbert Strang's lectures on linear algebra have had a significant impact, making math more accessible and enjoyable for millions of students. Linear algebra is a powerful and beautiful subfield of mathematics that is essential for understanding and solving real-world problems. The ability to break down and analyze complex data through concepts such as singular values and neural networks demonstrates the usefulness and applicability of linear algebra in fields like artificial intelligence and engineering. The emphasis on linear algebra and data analysis should be recognized and incorporated into mathematics education. Lastly, math plays an important role in politics and society, with its ability to provide certainty and reveal truths about the world.

## Summary & Key Takeaways

• Gilbert Strang is a renowned mathematics professor at MIT, known for his influential lectures on linear algebra.

• Linear algebra is a fundamental topic that has surged in importance, especially in the fields of artificial intelligence and data science.

• Strang highlights the four fundamental subspaces in linear algebra and the significance of singular values in breaking down matrices.