1 /*=========================================================================
2  *
3  *  Copyright Insight Software Consortium
4  *
5  *  Licensed under the Apache License, Version 2.0 (the "License");
6  *  you may not use this file except in compliance with the License.
7  *  You may obtain a copy of the License at
8  *
9  *         http://www.apache.org/licenses/LICENSE-2.0.txt
10  *
11  *  Unless required by applicable law or agreed to in writing, software
12  *  distributed under the License is distributed on an "AS IS" BASIS,
13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *  See the License for the specific language governing permissions and
15  *  limitations under the License.
16  *
17  *=========================================================================*/
18 #ifndef itkHeavisideStepFunction_h
19 #define itkHeavisideStepFunction_h
20 
21 #include "itkHeavisideStepFunctionBase.h"
22 #include "itkNumericTraits.h"
23 
24 namespace itk
25 {
26 /** \class HeavisideStepFunction
27  *
28  * \brief Implementation of the classical Heaviside step function.
29  *
30  * The Heaviside Step function is a piece-wise function:
31  *
32  *     http://en.wikipedia.org/wiki/Heaviside_step_function
33  *
34  *
35  * \author Mosaliganti K., Smith B., Gelas A., Gouaillard A., Megason S.
36  *
37  *  This code was taken from the Insight Journal paper:
38  *
39  *      "Cell Tracking using Coupled Active Surfaces for Nuclei and Membranes"
40  *      http://www.insight-journal.org/browse/publication/642
41  *      https://hdl.handle.net/10380/3055
42  *
43  *  That is based on the papers:
44  *
45  *      "Level Set Segmentation: Active Contours without edge"
46  *      http://www.insight-journal.org/browse/publication/322
47  *      https://hdl.handle.net/1926/1532
48  *
49  *      and
50  *
51  *      "Level set segmentation using coupled active surfaces"
52  *      http://www.insight-journal.org/browse/publication/323
53  *      https://hdl.handle.net/1926/1533
54  *
55  *
56  * \ingroup ITKCommon
57  */
58 template< typename TInput = float, typename TOutput = double >
59 class ITK_TEMPLATE_EXPORT HeavisideStepFunction:
60   public HeavisideStepFunctionBase< TInput, TOutput >
61 {
62 public:
63   ITK_DISALLOW_COPY_AND_ASSIGN(HeavisideStepFunction);
64 
65   using Self = HeavisideStepFunction;
66   using Superclass = HeavisideStepFunctionBase< TInput, TOutput >;
67   using Pointer = SmartPointer< Self >;
68   using ConstPointer = SmartPointer< const Self >;
69 
70   itkNewMacro(Self);
71 
72   itkTypeMacro(HeavisideStepFunction, HeavisideStepFunctionBase);
73 
74   using InputType = typename Superclass::InputType;
75   using OutputType = typename Superclass::OutputType;
76 
77   /** Evaluate at the specified input position */
78   OutputType Evaluate(const InputType & input) const override;
79 
80   /** Evaluate the derivative at the specified input position */
81   OutputType EvaluateDerivative(const InputType & input) const override;
82 
83 protected:
84   HeavisideStepFunction();
85   ~HeavisideStepFunction() override = default;
86 };
87 }
88 
89 #ifndef ITK_MANUAL_INSTANTIATION
90 #include "itkHeavisideStepFunction.hxx"
91 #endif
92 
93 #endif
94