code.delx.au - gnu-emacs-elpa/blob - packages/realgud/test/gcd.sh

   1 #!/usr/bin/env bash
   2 # Greatest Common Divisor in POSIX shell using Euclid's algorithm.  On
   3 # return, variable gcd_value is set and is the gcd of parameters $1
   4 # and $2. The GCD of a negative number is the same as the GCD of its
   5 # absolute value, since a negative number is -1 times its positive
   6 # value.  Negative numbers are set when there is an error; -1 is set
   7 # when the wrong number of parameters are given.
   8 gcd() {
   9     typeset -i a=$1
  10     typeset -i b=$2
  11     if (( a > b )) ; then
  12         a=$b
  13         b=$1
  14     fi
  15    if (( a == 1 || (b-a) == 0)) ; then
  16        gcd_value=$a
  17        return 0
  18    fi
  19    typeset -i c
  20    ((c=b-a))
  21    gcd $c $a
  22 }
  23
  24 gcd $1 $2
  25 echo $gcd_value