diff --git a/README.md b/README.md
index 4fbcdcc..67da554 100644
--- a/README.md
+++ b/README.md
@@ -219,3 +219,9 @@ Sometimes we only need [trigonometric functions](https://en.wikipedia.org/wiki/T
 * [sine function](https://en.wikipedia.org/wiki/Sine)
 * [cosine function](https://en.wikipedia.org/wiki/Trigonometric_functions#cosine)
 
+### [lms.hh](lms.hh)
+
+Some [least mean squares filter](https://en.wikipedia.org/wiki/Least_mean_squares_filter) implementations:
+* Normalized Least Mean Squares
+* Normalized Complex Least Mean Squares
+
diff --git a/lms.hh b/lms.hh
new file mode 100644
index 0000000..1a9978d
--- /dev/null
+++ b/lms.hh
@@ -0,0 +1,83 @@
+/*
+Least mean squares filter
+
+Copyright 2020 Ahmet Inan <inan@aicodix.de>
+*/
+
+#pragma once
+
+#include "bip_buffer.hh"
+
+namespace DSP {
+
+template <typename TYPE, int SIZE>
+class NLMS
+{
+	BipBuffer<TYPE, SIZE> history;
+	TYPE filter[SIZE];
+public:
+	NLMS()
+	{
+		for (int i = 0; i < SIZE; ++i)
+			filter[i] = 0;
+	}
+	inline operator const TYPE * () const
+	{
+		return filter;
+	}
+	TYPE operator () (TYPE input, TYPE desired, TYPE mu = 1)
+	{
+		const TYPE *hist = history(input);
+		TYPE estimate = 0;
+		for (int i = 0; i < SIZE; ++i)
+			estimate += filter[i] * hist[i];
+		TYPE error = desired - estimate;
+		TYPE power = 0;
+		for (int i = 0; i < SIZE; ++i)
+			power += hist[i] * hist[i];
+		if (power == 0)
+			return error;
+		TYPE rate = mu / power;
+		for (int i = 0; i < SIZE; ++i)
+			filter[i] += rate * error * hist[i];
+		return error;
+	}
+};
+
+template <typename CMPLX, int SIZE>
+class NCLMS
+{
+	typedef typename CMPLX::value_type VALUE;
+	BipBuffer<CMPLX, SIZE> history;
+	CMPLX filter[SIZE];
+public:
+	NCLMS()
+	{
+		for (int i = 0; i < SIZE; ++i)
+			filter[i] = 0;
+	}
+	inline operator const CMPLX * () const
+	{
+		return filter;
+	}
+	CMPLX operator () (CMPLX input, CMPLX desired, VALUE mu = 1)
+	{
+		const CMPLX *hist = history(conj(input));
+		CMPLX estimate = 0;
+		for (int i = 0; i < SIZE; ++i)
+			estimate += conj(filter[i]) * hist[i];
+		CMPLX error = conj(conj(desired) - estimate);
+		VALUE power = 0;
+		for (int i = 0; i < SIZE; ++i)
+			power += norm(hist[i]);
+		if (power == 0)
+			return error;
+		VALUE rate = mu / power;
+		for (int i = 0; i < SIZE; ++i)
+			filter[i] += rate * error * hist[i];
+		return error;
+	}
+};
+
+}
+