Errata for Mastering Algorithms with Perl

In the quadratic formula, the "2a" in the denominator needs to be enclosed in parentheses. When $a == 1, it doesn't show, but in general... Change return (-$b + sqrt($b*$b - 4*$a * $c)) / 2*$a; to return (-$b + sqrt($b*$b - 4*$a * $c)) / (2*$a);

Changed 0.6180334 to 0.618034

$tail = ${$node->[NEXT]}; to: $tail = $node->[NEXT];

$tail = ${$line->[NEXT]}; to: $tail = $line->[NEXT];

for ($pred=$list; $elem = $$pred; $pred = ${$elem->[NEXT]}) { to: for ($pred=$list; $elem = $$pred; $pred = $elem->[NEXT]) {

changed # tree_link has to be made to # $tree_link has to be made

$p->{height}.

my $i = $#$array and for ( $i = @$array; $i; ) { with the single line for (my $i = $#$array; $i; ) {.

"pa svenska: Mayer pa svenska: Mattson" and "auf Deutsch: Mayer auf Deutsch: Mattson" SHOULD BE: "pa svenska: Mattson pa svenska: Mayer" and "auf Deutsch: Mattson auf Deutsch: Mayer"

second line saying: # $small is the minimum element.

before the first $_[0] and a right parenthesis before the ;.

Change "halving N elements takes Theta(N) rounds" to "halving N elements takes Theta(log N) rounds". ("Theta" should be the capital Greek letter, of course.)

use integer;.

changed the line: my ( $last_of_first, $first_of_last, ) = to: my ( $first_of_last, $last_of_first ) =

of the second line. Changed $max to ($max+1) in the third line. In fifth line, changed $count[ $_] } 0..$max-1; to $counter[ $_ ] } 0..$max;.

my ($low, $high) = (0,scalar(@$array))

if ($array->[$cur] lt $target) { $low = $cur + 1; # too small, try higher } else { $high = $cur; # not too small, try lower

At the bottom of the page, changed the line that reads: next TRYELEM unless $_->{ $possible }; to next TRYELEM unless exists $_->{ $possible };.

removed keys from both.

Changed each to shift().

the leftmost vertex of the triangle is off. It should be at (-0.7, 0.7), not (-0.7, -0.7).

Middle of page: the sentence following "This displays an ASCII representation" should be a-b,b-c,c-d.

On each of these pages, the line print naive_string_matcher( "abcdefgh", "def" ), should be changed to print naive_string_matcher( "abcdefgh", "def" ), " ",

To add the space shown in the output, add " ", to the end of the line print naive_sequence_matcher( @a, @b ),.

Second prose paragraph: change "This trick is the Horner's rule." to "This trick is Horner's rule."

Halfway through the find_word() subroutine, add a semicolon to the end of my $line = <WORDS>.

At the bottom of page (in the Parse::Lex example code) change $token->getstring to $token->text. (The module's method name changed.)

In the formula at the bottom of the page, change the line below the big summation sign from "k = 1" to "i = 1".

After the last Perl statement, add another one: print "(6, 2): ", point_in_quadrangle( 6, 2, @quadrangle ), " ";

In the center of the page, change C<__closest_points_recurse> to C<_closest_points_recurse>.

change the nine instances of "e6" to "e3" In the last line of that program, change " km/h" to " million meters per hour" At the bottom of the page, change the program output to: The speed of Pluto is 21 million meters per hour The speed of Saturn is 34 million meters per hour The speed of Mars is 87 million meters per hour The speed of Uranus is 24 million meters per hour The speed of Jupiter is 47 million meters per hour The speed of Earth is 107 million meters per hour The speed of Venus is 126 million meters per hour The speed of Neptune is 17 million meters per hour The speed of Mercury is 172 million meters per hour

The fractal program and image are correct, but the image is squashed a little bit because a rectangular region of the complex plane is being displayed in a square canvas. To unsquash the image, change these lines on page 486: use constant RIGHT => 0.5; use constant TOP => 1.25; use constant BOTTOM => -1.25;

if ($ci < $#primes) should be: if ($ci < $#heap)

delete: $num -= $div * $prime;

Change the line that reads #!/bin/perl -nle to #!/usr/bin/perl -nl.

Change the line that reads use SSLeah; to use SSLeay;.

change "cannot encrypt with the public key instead" to "cannot encrypt with the private key instead".

change the line print "$k = $v "; to print "$key = $value ";

change the line for (1..100) { print rand_dist(\%a) } to for (1..100) { print rand_dist_perfect(\%a) }.

Change the line poker_disp_many( to display_poker_many(.

there are a list of two-character items. Insert " of " between the two characters. For instance, 5C should become 5 of C, and so on for the other 29 character pairs.

change z to zi. Middle three prose paragraphs: change both instances of 5.124 to 7.805. Change -10 to 16 and 10 to 16; change -5 to 8 and 5 to 8; change "However, we'd" to "We'd". Change the text between "The actual figure" to "as it well might not:" to the following: The actual figure is 4+(2*3)+(3*4)+(4*1)+(5*2) = 36, also about the expected value. However, it is not certain that falling pennies would follow a Gaussian distribution:

Remove one of the right parentheses after $expected_mean.

change: use Statistics::Table::t ($lo, $hi) = t_significance($t, $degrees, $tails); print "The probability that your data is due to chance: "; to use Statistics::Table::t; ($lo, $hi) = t_significance($t, scalar(@data) - 1, 1); print "The probability that your data are not due to chance: ";

In Figures 15-3 and 15-4, the first number on the x-axis should be 0, not 2500.

Immediately before the first line of code, add: use Statistics::Table::t; Change if ($hi <= 0.05) { to: if ($lo >= 0.95) {

change both occurrences of 1.2 to 1.4 change 6000 to 7000 and change "== 7887.20, respectively." to ", which is about 11595.5.". (There's no monospace in the replacement text.)

make the following changes: Change the two instances of 0.1 to 0.01 Change 366 to 365 Change 6.45 to 6.46 Change both occurrences of print to printf "%.2f ",.

replace [&f, &g] with [&f, &g, &h]. In the code's output, replace 266666668.176214 (which is what Digital Unix reports) with NaN (which is what Red Hat Linux and Solaris report).

in the prose paragraph beginning "The roots will then be", change c/a to c/q.

change the first occurrence of log($x) to 100*log($x) and change x3-log(x) to x3-100log(x). Change the sentence "When will your company run out of money?" to "When will your company start to earn money?" In the next full prose paragraph, change the second sentence to: If we change our initial low guess from a 2 to a 1, it fails: root(&cashflow, 1, 100, .001) returns nothing at all, because the subroutine returns early if the function value at both guesses are positive. If it didn't, it would reach the maximum number of iterations without finding a root.

Remove the # in front of sub solve, and remove $error_var, from the line beginning my ($i, ....

In the third line of sub poly_fit, change: my($i, $j, $y, @solution) to my($i, $j, $x, $y).