mathlib: added exponential curve function

src/lib/mathlib/math/Expo.hpp

@@ -0,0 +1,56 @@
+/****************************************************************************
+ *
+ *   Copyright (c) 2017 PX4 Development Team. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file Expo.hpp
+ *
+ * So called exponential curve function implementation.
+ * It's essentially a linear combination between a linear and a cubic function.
+ */
+
+#pragma once
+
+#include <platforms/px4_defines.h>
+#include <stdint.h>
+
+namespace math
+{
+
+template<typename _Tp>
+inline const _Tp expo(const _Tp &value, const _Tp &e)
+{
+	_Tp x = constrain(value ,(_Tp)-1, (_Tp)1);
+	return (1-e)*x + e*x*x*x;
+}
+
+}

src/lib/mathlib/mathlib.h

@@ -45,5 +45,7 @@
 #include "math/Matrix.hpp"
 #include "math/Quaternion.hpp"
 #include "math/Limits.hpp"
+#include "math/Expo.hpp"
 #include "math/matrix_alg.h"
+
 #endif