# 正接(近似) Tangent Approximation
# 引数 値 ($X)
# 戻り値 正接(ラジアン) ($TangentApproximation)
sub TANGENT{
	my ($X) = @_;
	my $TangentApproximation = 0;
	my $Sine = &SINE($X);
	my $Cosine = &COSINE($X);
	
	# 正接(近似) Tangent
	$TangentApproximation = $Sine / $Cosine;

	return $TangentApproximation;
}


# 正弦(近似) Sine Approximation
# 引数 値 ($x)
# 戻り値 正弦(ラジアン) ($SineApproximation)
sub SINE{
	my ($x) = @_;
	my $SineApproximation = 0;
	my $X = abs($x);
	my $Sum = 0;
	my $Sign = 0;
	my $Num = 0;
	my $Factorial = 1;
	my $Pi = atan2(1, 1) * 4;
	my $Radian2Pi = 2 * $Pi;
	my $Expansion = 20;
	
	# 360度以上
	if($X >= $Radian2Pi){
		$X = $X - (int($X / $Radian2Pi) * $Radian2Pi);
	}
	
	for(my $i = 0; $i <= $Expansion; $i++){
		# 符号
		$Sign = (($i % 2) == 0 ? 1: -1);
		# 分子
		$Num = $X ** ((2 * $i) + 1);
	
		if($i != 0){
			# 分母 階乗
			for(my $j = ((2 * $i) + 1); $j > ((2 * ($i - 1)) + 1); $j--){
				$Factorial = $Factorial * $j;
			}
		}
	
		$Sum += $Sign * ($Num / $Factorial);
	}
	
	# $xが負
	$Sum = -$Sum if($x < 0);
	
	# 正弦(近似) Sine
	$SineApproximation = $Sum;
	
	return $SineApproximation;
}


# 余弦(近似) Cosine Approximation
# 引数 値 ($x)
# 戻り値 余弦(ラジアン) ($CosineApproximation)
sub COSINE{
	my ($x) = @_;
	my $CosineApproximation = 0;
	my $Sum = 0;
	my $X = abs($x);
	my $Sign = 0;
	my $Num = 0;
	my $Factorial = 1;
	my $Pi = atan2(1, 1) * 4;
	my $Radian2Pi = 2 * $Pi;
	my $Expansion = 20;
	
	# 360度以上
	if($X >= $Radian2Pi){
		$X = $X - (int($X / $Radian2Pi) * $Radian2Pi);
	}
	
	for(my $i = 0; $i <= $Expansion; $i++){
		# 符号
		$Sign = (($i % 2) == 0 ? 1: -1);
		# 分子
		$Num = $X ** (2 * $i);
	
		if($i != 0){
			# 分母 階乗
			for(my $j = 2 * $i; $j > (2 * ($i - 1)); $j--){
				$Factorial = $Factorial * $j;
			}
		}
	
		$Sum += $Sign * ($Num / $Factorial);
	}
	
	# 余弦(近似) Cosine
	$CosineApproximation = $Sum;
	
	return $CosineApproximation;
}