09-15-08 In Challenge 5.1, "for i=1:n" should be "for i=1:m".
09-15-08 In Challenge 5.8, after "same QR as above", insert "up to choice of signs for columns of Q and rows of R".
09-16-08 In Challenge 5.14, insert "+" after the three dots (3 times in the first 3 lines).
09-16-08 In Challenge 5.19, insert "+" after the three dots (2 times in line 2).
09-16-08 In Challenge 8.6, insert "+" after the three dots (in line 4).
09-18-08 In Challenge 5.13, delete the 2nd paragraph.
09-19-08 In Challenge 5.19 (a), change "u_i^T b" to "u_i^* b".
09-22-08 In Challenge 5.7, in the last line, the only restriction on s is that its absolute value equals 1. The choice specified there is one such value.
09-23-08 In Challenge 5.9, last line, change "q_j*" to "q_{ell}*".
09-23-08 In Challenge 5.10 (c): In step 5, the update should be "2 u (u^T R(j:m,j:n))".
09-25-08
In Challenge 5.14, in the 2nd displayed equation, there should be r u-vectors, not r-1.
In 3rd displayed equation, in the 3rd column of W, the subscripts on lambda
should go from 1 to r.
09-30-08 In the answer for Challenge 7.1 (b): insert at the end of the last sentence: "but set the 6th element to zero".
10-01-08 Delete the 2nd paragraph in the answer to Challenge 5.13. Insert at the end of the 1st paragraph, "The roots are -0.5398 and 0.2389."
10-02-08 In Challenge 5.19 (a), change the transpose on u_i to a conjugate transpose.
10-22-08 In Challenge 9.9, "myxnow" should be "x" (twice).
11-13-08 In Challenge 16.4, change "myrand" to "randmy" twice. Also, we divide by the "standard deviation", not the "variance".
11-13-08 The Matlab codes for the solution were misnumbered, and one was missing. They have been reposted.
11-24-08 In Challenge 20.9, change "4" to "5", twice, in the second bullet.
12-02-08 In Challenge 20.19, change all y's to u's, to match the text. Change "Subtracting" to "Adding". In the displayed equation after that, change "2h y(t)" to "2 y(t)".