smoothstep.cpp

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/*
 *  SPDX-FileCopyrightText: Copyright 2021, Siavash Ameli <sameli@berkeley.edu>
 *  SPDX-License-Identifier: BSD-3-Clause
 *  SPDX-FileType: SOURCE
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the license found in the LICENSE.txt file in the root
 *  directory of this source tree.
 */
 
 
// =======
// Headers
// =======
 
#include <cmath>  // tanh
#include "./smoothstep.h"
 
 
// ===========
// Smooth Step
// ===========
 
 
SmoothStep::SmoothStep(double alpha_)
{
    this->alpha = alpha_;
}
 
 
// ====================
// Smooth Step function (float)
// ====================
 
 
float SmoothStep::function(const float lambda_) const
{
    return 0.5f * (1.0f + std::tanh(
        static_cast<float>(this->alpha) * lambda_));
}
 
 
// ====================
// Smooth Step function (double)
// ====================
 
 
double SmoothStep::function(const double lambda_) const
{
    return 0.5 * (1.0 + std::tanh(this->alpha * lambda_));
}
 
 
// ====================
// Smooth Step function (long double)
// ====================
 
 
long double SmoothStep::function(const long double lambda_) const
{
    return 0.5l * (1.0l + std::tanh(
        static_cast<long double>(this->alpha) * lambda_));
}