#!/bin/sh -- # A comment mentioning perl, indented for bash's sake.
eval 'exec perl -S $0 ${1+"$@"}'
        if 0;

chop($Program = `basename $0`);

$Usage = <<"END";

$Program: sum up numbers and optionally perform averages.

Usage: $Program <options>

Options:
	-t		place "Total:" string in output line,
			-n to turn off.
	-a		perform averages (ave, dev, stderr).
	-pm		with plus minus.
			
Notes:
	The standard error estimate assume all the data
	are statistically independent of course.

END

$no_total = 1;
$do_ave = 0;
$do_chi = 0;
$plus_minus = 0;

LOOP:	
while (@ARGV) {
    $_ = shift;
    CASE: {
	/^-n/ && ($no_total = 1, last CASE);
	/^-t/ && ($no_total = 0, last CASE);
	/^-a/ && ($do_ave = 1, last CASE);
	/^-chi/ && ($do_ave = 1, $do_chi = 1, last CASE);
	/^-pm/ && ($do_ave = 1, $plus_minus = 1, last CASE);
	/^-d$/ && ($Debug = 1, last CASE);
	/^--$/ && (last LOOP);	# -- means end of switches
	/^-(-.*)$/ && (unshift(@ARGV, $1), last CASE);
	/^(-h|-help)$/ && ((print STDERR $Usage), exit 0, last CASE);
	if ( /^-(..+)$/ ) {	# split bundled switches:
		local($y, $x) = ($1, '');
		foreach $x (reverse(split(//, $y))) { unshift(@ARGV,"-$x") };
		last CASE;
	}
	/^-/ && ((print STDERR "Invalid arg: $_\n$Usage"), exit 1, last CASE);
	unshift(@ARGV,$_);
	last LOOP;
    }
}
$sum = 0.0;
$dev = 0.0;
$n = 0;

while (<>) {
	chop;
	$x = &trim($_);
	next if $x eq '';
	if ( $do_chi ) {
		($x, $err) = split(/\s+/, $_);
		$Vals[$n] = $x;
		$Errs[$n] = $err;
	}
	$n++;
	$sum = $sum + $x;
	if ( $do_ave ) {
		$dev += ($x ** 2);
	}
}


if ( $do_ave ) {
	$n = 1 if $n == 0;
	$ave = $sum / $n;
	$dev = $dev / $n;
	$dev = $dev - ($ave ** 2);
	if ( $dev > 0.0 ) {
		$dev = sqrt($dev);
	} else {
		$dev = 0.0;
	}
	$err = $dev/sqrt($n);

	$ave = sprintf("%12.6f", $ave);
	$dev = sprintf("%12.6f", $dev);
	$err = sprintf("%12.6f", $err);

} else {
	$sum = sprintf("%12.5f",$sum);
}


if ( $do_ave ) {
	$ave =~ s/^\s*//;
	$dev =~ s/^\s*//;
	$err =~ s/^\s*//;
	$chi = '';
	if ( $do_chi ) {
		$chi = 0.0;
		for ($i=0; $i< @Errs; $i++) {
			$dx = ($Vals[$i] - $ave)/$Errs[$i];
			$chi += $dx ** 2;
		}
		$chi = sprintf("%12.6f", $chi);
		$chi =~ s/^\s*//;
		$chi = "  chi^2: $chi";
	}
	if ( $plus_minus ) {
		print "$ave +/- $err  dev\[$n]: $dev$chi\n";
	} else {
		print "ave: $ave  dev: $dev  err\[$n]: $err$chi\n";
	}
} elsif ( $no_total ) {
	$sum = &trim($sum);
	print "$sum\n";
} else {
	print "Total: $sum\n";
}

exit 0;

sub trim {
	local($x) = @_;
	$x =~ s/^\s*//;
	$x =~ s/\s*$//;

	return $x;
}