1. The problem statement, all variables and given/known data My professor wrote a paper about tennis a couple of years ago and he's asked us to recreate some of his results. So I have this vector: I'm supposed to multiply it with this matrix: to get (p1, 0, 0, 0, q1). p1 is: q1 is similar but the p's and q's are switched around. 2. Relevant equations This is the paper my teacher wrote and from which the above screenshots came from: http://www.math-cs.ucmo.edu/~mjms/2001.3/Yliuten.pdf [Broken] 3. The attempt at a solution I have tried and tried and tried to multiply this vector and matrix and, while I get the same answer every time, it does not look anything like p1 or q1. This is what I get: I had a friend do it for me and he got the same answer too. So maybe I didn't read the paper carefully enough?