My dad figured this out years ago.
The string method work for all matrices, and it is at least ten times quicker to “do” than to “write about”.
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Matrix multiplication without tears!
Filed under algebra, education, math, teaching, transformations, Uncategorized
You had me at line 1. But then it took me 3 goes.
{ I am prompted to write as I recently asked my Dad (not a Math-man) what he knew about X (moderately new in an offshoot field to his area). “Never heard of it”. He had met Nelkon though. The Physics-text legend. (BTW I arrive here via ur comment praising Gelbaum). I don’t have any copies of those school books, indeed all my undergrad books have gone too. }
Anyway my point is that the 3D example you illustrate reminded me of my best lecture: Palindrome testing in a particular computer language. Twenty years later and my lecture notes (too) are gone but the new fangled way is:
http://stackoverflow.com/questions/8362572/check-if-a-string-is-palindrome
What is interesting to us Programmers is the feud over what is good and bad programming. I only remember one message (of experience) that I had to give when I was teaching the language C: “String think pointer (to char)” …… the first is a vector, the second: I would announce at the start of my lecture courses was my purpose.