Why do linear algebra books have this cover? Why do many linear algebra books have covers like this? I think the one on Hadamard matrices hints at me that they are just representing the entries of the matrix as colors (hence why it is black and white in the Hadamard one). Although the Hadamard matrix one is the only one in which not all of the components are perfect rectangles, so perhaps something else is being captured. Does anyone have any idea as to what these covers are? Perhaps there is no common trend and I am just reading too much into it but I would like to know if someone has some insight.
Thank you in advance and best regards.

 A: From the preface of Matrix Analysis:
"The cover art for the second edition was the result of a lucky encounter on a Deltaflight  from  Salt  Lake  City  to  Los  Angeles  in  spring  2003.  The  young  man  in  themiddle  seat  said  he  was  an  artist  who  paints  abstract  paintings  that  are  sometimesmathematically inspired. In the course of friendly conversation, he revealed that hisspecial area of mathematical enjoyment was linear algebra, and that he had studiedMatrix Analysis.  After  mutual  expressions  of  surprise  at  the  chance  nature  of  ourmeeting, and a pleasant discussion, we agreed that appropriate cover art would enhancethe visual appeal of the second edition; he said he would send something to consider.In due course a packet arrived from Seattle. It contained a letter and a stunning 4.5- by5-inch color photograph, identified on the back as an image of a 72- by 66-inch oil oncanvas, painted in 2002. The letter said that “the painting is entitledSurprised Againon the Diagonaland is inspired by the recurring prevalence of the diagonal in mathwhether it be in geometry, analysis, algebra, set theory or logic. "
