stir_math.h

/*
  Copyright (C) 2016, UCL
  This file is part of STIR.

  SPDX-License-Identifier: Apache-2.0

  See STIR/LICENSE.txt for details
*/

#ifndef __stir_STIR_MATH_H__
#define __stir_STIR_MATH_H__

using std::cout;
using std::endl;
using std::fstream;
using std::transform;
using std::max;
using std::min;
using std::string;
using std::vector;

USING_NAMESPACE_STIR

// Nikos Efthimiou: Minimal header file to be able to use this class from other
// places in the code.

// a function object that takes a power of a float, and then multiplies with a float, and finally adds a float
class pow_times_add
{
public:
  pow_times_add(
      const float add_scalar, const float mult_scalar, const float power, const float min_threshold, const float max_threshold)
      : add(add_scalar),
        mult(mult_scalar),
        power(power),
        min_threshold(min_threshold),
        max_threshold(max_threshold)
  {}

  float operator()(float const arg) const
  {
    const float value = min(max(arg, min_threshold), max_threshold);
    return add + mult * (power == 1 ? value : pow(value, power));
  }

private:
  const float add;
  const float mult;
  const float power;
  const float min_threshold;
  const float max_threshold;
};

#endif