#!/usr/bin/perl -w

# Time-stamp: <18 Feb 2000 18:03 charpov@cs.unh.edu>
# without these two lines, the pi number of this program is 2.8784916685157

# computes the pi approximation of a file
# uses the fact that the probability for two integers to be coprime
# is 6/pi^2

use strict;

# assume the first line is one (the first test will be positive, and $p will
# be nonzero).
my ($n, $p, $l) = (0, 0, 1);

# for all nonempty and nonnull lines
while (<>) {
  # conversion: returns (in hexa) the bits in the line seen as a number
  # chop the \n at the end of lines (if not, lines are never coprime)
  # dc wants hexa numbers to be uppercased
  chomp;
  $_ = uc unpack "H*", $_;
    if (not /^0*$/) {
    # test the current line with the previous one; increase by one the 
    # number of tests; increase the number of positive tests if numbers 
    # are coprime
    # package Math::BigInt is so slow that it's more efficient to fork and
    # ask dc to compute the gcd
    $n++;
    $p++ if (`echo "16i$l $_ sa[sblalbdsa%d0<.]ds.xlap" | /usr/bin/dc` eq "1\n");
    $l = "$_";
    # print the current approximation of pi
    # print "($p/$n)\n"; # for debug
    print (sqrt (6.0*$n/$p)."\n");
  }
}