diff --git a/window.hh b/window.hh
index 9a2ee8b..e38c470 100644
--- a/window.hh
+++ b/window.hh
@@ -7,6 +7,8 @@ Copyright 2018 Ahmet Inan <inan@aicodix.de>
 #ifndef WINDOW_HH
 #define WINDOW_HH
 
+#include "kahan.hh"
+
 namespace DSP {
 
 template <int TAPS, typename TYPE>
@@ -65,6 +67,33 @@ public:
 	inline operator const TYPE * () const { return w; }
 };
 
+template <int TAPS, typename TYPE>
+class Kaiser
+{
+	TYPE w[TAPS];
+	TYPE i0(TYPE x)
+	{
+		Kahan<TYPE> sum(1.0);
+		TYPE val = 1.0;
+		// converges for -3*M_PI:3*M_PI in less than:
+		// float: 25 iterations
+		// double: 35 iterations
+		for (int n = 1; n < 35; ++n) {
+			TYPE tmp = x / TYPE(2 * n);
+			sum(val *= tmp * tmp);
+		}
+		return sum();
+	}
+public:
+	Kaiser(TYPE a)
+	{
+		for (int n = 0; n < TAPS; ++n)
+			w[n] = i0(TYPE(M_PI) * a * std::sqrt(TYPE(1) - std::pow(TYPE(2 * n) / TYPE(TAPS - 1) - TYPE(1), TYPE(2)))) / i0(TYPE(M_PI) * a);
+	}
+	inline TYPE operator () (int n) { return n >= 0 && n < TAPS ? w[n] : 0; }
+	inline operator const TYPE * () const { return w; }
+};
+
 }
 
 #endif