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+/*
+ fuzzylite (R), a fuzzy logic control library in C++.
+ Copyright (C) 2010-2017 FuzzyLite Limited. All rights reserved.
+ Author: Juan Rada-Vilela, Ph.D. <jcrada@fuzzylite.com>
+
+ This file is part of fuzzylite.
+
+ fuzzylite is free software: you can redistribute it and/or modify it under
+ the terms of the FuzzyLite License included with the software.
+
+ You should have received a copy of the FuzzyLite License along with
+ fuzzylite. If not, see <http://www.fuzzylite.com/license/>.
+
+ fuzzylite is a registered trademark of FuzzyLite Limited.
+ */
+
+#ifndef FL_CONCAVE_H
+#define FL_CONCAVE_H
+
+#include "fl/term/Term.h"
+
+namespace fl {
+
+    /**
+      The Concave class is an edge Term that represents the concave membership
+      function.
+
+      @image html concave.svg
+
+      @author Juan Rada-Vilela, Ph.D.
+      @see Term
+      @see Variable
+      @since 5.0
+     */
+    class FL_API Concave : public Term {
+    private:
+        scalar _inflection, _end;
+    public:
+        explicit Concave(const std::string& name = "",
+                scalar inflection = fl::nan,
+                scalar end = fl::nan,
+                scalar height = 1.0);
+        virtual ~Concave() FL_IOVERRIDE;
+        FL_DEFAULT_COPY_AND_MOVE(Concave)
+
+        virtual std::string className() const FL_IOVERRIDE;
+        /**
+          Returns the parameters of the term as
+          @return `"inflection end [height]"`
+         */
+        virtual std::string parameters() const FL_IOVERRIDE;
+        /**
+          Configures the term with the parameters given
+          @param parameters as `"inflection end [height]"`
+         */
+        virtual void configure(const std::string& parameters) FL_IOVERRIDE;
+
+        virtual Complexity complexity() const FL_IOVERRIDE;
+
+        /**
+          Computes the membership function evaluated at @f$x@f$
+          @param x
+          @return @f$\begin{cases}
+          h \times (e - i) / (2e - i - x) & \mbox{if $i \leq e \wedge x < e$
+          (increasing concave)} \cr
+          h \times (i - e) / (-2e + i + x) & \mbox{if $i > e \wedge x > e$
+          (decreasing concave)} \cr
+          h & \mbox{otherwise} \cr
+          \end{cases}@f$
+
+          where @f$h@f$ is the height of the Term,
+                @f$i@f$ is the inflection of the Concave,
+                @f$e@f$ is the end of the Concave
+         */
+        virtual scalar membership(scalar x) const FL_IOVERRIDE;
+
+        virtual scalar tsukamoto(scalar activationDegree,
+                scalar minimum, scalar maximum) const FL_IOVERRIDE;
+
+        virtual bool isMonotonic() const FL_IOVERRIDE;
+
+        /**
+          Sets the inflection of the curve
+          @param inflection is the inflection of the curve
+         */
+        virtual void setInflection(scalar inflection);
+        /**
+          Gets the inflection of the curve
+          @return the inflection of the curve
+         */
+        virtual scalar getInflection() const;
+
+        /**
+          Sets the end of the curve
+          @param end is the end of the curve
+         */
+        virtual void setEnd(scalar end);
+        /**
+          Gets the end of the curve
+          @return the end of the curve
+         */
+        virtual scalar getEnd() const;
+
+        virtual Concave* clone() const FL_IOVERRIDE;
+
+        static Term* constructor();
+    };
+}
+#endif  /* FL_CONCAVE_H */
+