Posts 1 - 10 of 15

Results for: Magic Squares

What is A\A?

The answer: A\A is always I, except when it isn't.... read more >>

“Odd Rock” on Mars Exhibits (Almost) Magic Square 1

A news story released yesterday, March 31,by c|net has the headline... read more >>

CR and CAB, Rank Revealing Matrix Factorizations 5

The rank of a linear transformation is a fundamental concept in linear algebra and matrix factorizations are fundamental concepts in numerical linear algebra. Gil Strang's 2020 Vision of Linear Algebra seeks to introduce these notions early in an introductory linear algebra course.... read more >>

Holiday Greetings 2020

I want to share some colorful images featuring the seven colors in the MATLAB axes color order.... read more >>

Notes on CR and west0479 4

My post a few days ago, Gil Strang and the CR Matrix Factorization, generated a lot of email. Here is the resulting follow-up to that post.... read more >>

Gil Strang and the CR Matrix Factorization 4

My friend Gil Strang is known for his lectures from MIT course 18.06, Linear Algebra, which are available on MIT OpenCourseWare. He is now describing a new approach to the subject with a series of videos, A 2020 Vision of Linear Algebra. This vision is featured in a new book, Linear Algebra for Everyone.... read more >>

Color Order for Line Plots 1

Line plots with a color order from one of our color maps are useful, and pretty.... read more >>

Quadruple Precision, 128-bit Floating Point Arithmetic 9

The floating point arithmetic format that occupies 128 bits of storage is known as binary128 or quadruple precision. This blog post describes an implementation of quadruple precision programmed entirely in the MATLAB language.... read more >>

Apologies to Gram-Schmidt

This is a follow-up to my previous follow-up, posted several days ago. A very careful reader, Bruno Bazzano, contributed a comment pointing out what he called "a small typo" in my code for the classic Gram-Schmidt algorithm. It is more than a small typo, it is a serious blunder. I must correct the code, then do more careful experiments and reword my conclusions.... read more >>

Compare Gram-Schmidt and Householder Orthogonalization Algorithms 4

This is a follow-up to my previous post. Classical Gram-Schmidt and Modified Gram-Schmidt are two algorithms for orthogonalizing a set of vectors. Householder elementary reflectors can be used for the same task. The three algorithms have very different roundoff error properties.... read more >>

Posts 1 - 10 of 15