addup unix script

#
#       @(#) addup.sh 1.0 90/07/19
#
#       Copyright (C) Steven J. Bensky, 1990
#       Adds up a column (default=last) of numbers in a file.
#       95/05/16 updated to allow (999) negative style numbers.

case $1 in
-[0-9])
        COLUMN=`echo $1 | tr -d -`
        shift
;;
*)
        COLUMN="NF"
;;
esac
echo "Adding up column .. $COLUMN .. of file(s) .. $*"

nawk  ' OFMT="%.2f"                                       # 1 "%12.2f"
        { x = '$COLUMN'                                   # 2
          neg = index($x, "$")                            # 3
          if (neg > 0) X = gsub("\\$", "", $x)
          neg = index($x, ",")                            # 4
          if (neg > 1) X = gsub(",", "", $x)
          neg = index($x, "(")                            # 8 neg (123 & change
          if (neg > 0) X = gsub("\\(", "", $x)
          if (neg > 0) $x = (-1 * $x)                     # it to "-123.00"
          neg = index($x, "-")                            # 5
          if (neg > 1) $x = (-1 * $x)                     # 6
          t += $x                                         # 7
          print "x is <<<", $x+0, ">>> running balance:", t
        } ' $*

# 1.  set numeric format to eliminate rounding errors
# 1.1 had to reset numeric format from 12.2f to .2f 95/05/16
#     when a computed number is assigned to a variable ( $x = (-1 * $x) )
#     it causes $x to use the OFMT so -1.23 = "________-1.23" vs "-1.23"
#     and that causes my #5 (negative check) to not work correctly because
#     the index returns a number >1 and to the neg neg than becomes a positive
#     this only occurs if the number happened to b a "(" neg number
# 2.  find the field we want to add up (comes from the shell or defaults
#     to the last field "NF") in the file
# 3.  check for a dollar sign ($) in the number - if there get rid of it
#     so we may add it correctly - $12 $1$2 $1$2$ $$1$$2$$ all = 12
# 4.  check for a comma (,) in the number - if there get rid of it so we
#     may add it correctly - 1,2 12, 1,,2 1,,2,, all = 12   (,12=0)
# 5.  check for negative numbers
# 6.  if x is a negative number in the form 999- "make" it a recognized
#     number like -999 - if x is a negative number like -999 already
#     the test fails (y is not >1) and this "true" negative is not made
#     positive
# 7.  accumulate the total
# 8.  if x is a negative number in the form (999) "make it a recognized
#     number like -999
# * Note that a (-9) (neg neg number) returns a postive
# * Mite not work rite with all forms of all numbers using $-,+. etc. *