In yesterday’s post<\/a> I showed a Perl program, called from the command line with the input value, to find the cube root of a number. Here are some points to help a casual reader understand it:<\/p>\n $ARGV[0]<\/span> refers to the first command-line argument. Let’s imagine the program is stored as cuberoot.txt<\/span>. If the user wants the cube root of -64, the program will be called from the command line as follows:<\/p>\n perl cuberoot.txt -64<\/span><\/p>\n The if<\/span> statement checks for negativity; my version of Perl isn’t happy to exponentiate a negative number by 1\/3. I just make $input<\/span> positive, take that cube root, then multiply the answer by negative 1. Later I change $input<\/span> back to negative so it’s correct in the answer statement printed to the screen.<\/p>\n printout<\/span> is a subroutine listed at the bottom of the program. It’s called by &printout<\/span>. To my knowledge, a subroutine is called using an ampersand in front of its name.<\/p>\n HTH:)<\/p>\n Source:<\/p>\n McGrath, Mike. Perl in easy steps<\/u>. Southam: Computer Step, 2004.<\/p>\n