Below is the Perl code from last post, this time with some comments (recall that # denotes a comment in Perl): This random walk is a great springboard to summer posts about probability. Of course, we never need a reason to return to Perl:)<\/p>\n Source:<\/p>\n McGrath, Mike. Perl in easy steps<\/u>. Southam: Computer Step, 2004.<\/p>\n
\n
\n#!\/usr\/bin\/perl # needed for Linux (Unix)<\/span>
\nprint “Welcome to the random walk simulation.\\n\\n”;
\nprint “Enter the number of steps you’d like, please.\\n\\n”;
\n$steps=<STDIN>;# <STDIN> fetches user input<\/span>
\nchomp $steps;# chomps the newline from the input<\/span>
\n$pos=0;# walker’s position starts as 0<\/span>
\nfor($i=0;$i<$steps;$i++){
\n$rn=int(rand(100)); # Perl random number function<\/span>
\nif($rn % 2==0){# % is Perl’s modulus operator<\/span>
\n$pos=$pos-1;
\n}# if the random number is even, walker steps left<\/span>
\nelse{
\n$pos++; # adds 1 to the $pos value<\/span>
\n}# otherwise, walker steps right<\/span>
\n}
\nif($pos<0){\n$dir=\"left\";\n$pos*=-1;# means $pos=$pos*-1;<\/span>
\n}
\nelse{
\n$dir=”right”;
\n}
\nprint “The position, after $steps steps, is $pos units $dir\\n\\n”;
\n<\/span><\/p>\n