#!/usr/bin/perl -w
use strict; use warnings;

my $numberofinputnodes = 2; my $numberofhiddennodes = 2; my $learningrate = .1;
my $maxepochs = 10; my $errormargin = .1; my @weight = (.6,.6,.6);
my @hiddenweight = (.6,.6,.6);
my @data = (["-1","0.000000","0.000000","0"],["-1","0.000000","1.000000","1"],
["-1","1.000000","0.000000","1"],["-1","1.000000","1.000000","0"]);
my $numberofepochs = 1; my $net = 0; my $netk = 0; my $avgrmse = 0; my @outputh = ();
my @outputk = (); my $deltak = 0; my $deltah = 0; my @rmse = (); my $maxrmse =0;

while (($numberofepochs <= $maxepochs) && (($avgrmse == 0) || ($avgrmse >= $errormargin))){
	$avgrmse = 0;
	for (my $j=0; $j <= $#data; $j++) {
		for (my $k=0; $k < $#{$data[0]}; $k++){
			$net = $net + $weight[$k]*$data[$j][$k];
		}
		$outputh[$j] = 1 / (1 + exp(-$net));
		$net=0;
		for (my $o = 0; $o <= $numberofhiddennodes; $o++){
			if ($o==0){
				$netk = -$hiddenweight[0];	
			}
			$netk = $netk + $hiddenweight[$o]*$outputh[$j];
		}
		$outputk[$j] = 1 / (1 + exp(-$netk)); $netk=0;
		$deltak = $outputk[$j]*(1 - $outputk[$j])*($data[$j][-1] - $outputk[$j]);
		my @deltah;
		for (my $o = 0; $o < $#{$data[0]}; $o++){
			$deltah[$o] = $outputh[$j]*(1-$outputh[$j])*$weight[$o]*$deltak;
		}
		for (my $m=0; $m < $#{$data[0]}; $m++){
			my $update = $learningrate*$deltah[$m]*$data[$j][$m];
			$weight[$m] = $weight[$m] + $update;
		}
		for (my $n=0; $n <= $numberofhiddennodes; $n++){
			my $update = $learningrate*$deltak*$outputk[$j];
			$hiddenweight[$n] = $hiddenweight[$n] + $update;
		}
		$deltak=0; @deltah = ();
	} 
	for (my $j=0; $j <= $#data; $j++) {
		for (my $k=0; $k < $#{$data[0]}; $k++){
			$net = $net + $weight[$k]*$data[$j][$k];
		}
		$outputh[$j] = 1 / (1 + exp(-$net));
		for (my $o = 1; $o < $numberofhiddennodes; $o++){
			$netk = $netk + $hiddenweight[$o]*$outputh[$j];
		}
		$netk = $netk - $hiddenweight[0]; $outputk[$j] = 1 / (1 + exp(-$netk));
		$net = 0; $netk = 0;
	}
	my $totalrmse = 0;
	for my $q (0..$#data){
		$rmse[$q] = sqrt(($data[$q][-1] - $outputk[$q])**2);
		$totalrmse = $totalrmse + $rmse[$q];
	}
	$avgrmse = $totalrmse / ($#data +1); @rmse = sort( {$a <=> $b} @rmse); 
	$maxrmse = $rmse[-1];
	if($numberofepochs==$maxepochs){
		print "\n","***** Epoch $numberofepochs *****", "\n";
		print "Maximum RMSE: $maxrmse", "\n";
		print "Average RMSE: $avgrmse", "\n";
	}
	@rmse = (); $totalrmse = 0;	$numberofepochs++;
}
exit;

##</code><code>##

***** Epoch 10 *****
Maximum RMSE: 0.570149294921984
Average RMSE: 0.500071929555965

##</code><code>##

***** Epoch 10 *****
Maximum RMSE: 0.5432215742673802
Average RMSE: 0.4999911891911738