make_meta_gaussian.cpp

#include <iostream>
#include <fstream>
#include <cmath>

#define CUIMG_PI 3.14159265f

template <int N>
float gaussian_derivative(float sigma, int x);

template <>
float gaussian_derivative<0>(float sigma, int x)
{
  return (1 / (sqrt(2 * CUIMG_PI) * sigma))
    * exp(-(x * x) / (2 * sigma * sigma));
}

template <>
float gaussian_derivative<1>(float sigma, int x)
{
  return -(x / (sqrt(2 * CUIMG_PI) * std::pow(sigma, 3)))
    * exp(-(x * x) / (2 * sigma * sigma));
}

template <>
float gaussian_derivative<2>(float sigma, int x)
{
  return (((x - sigma) * (x + sigma)) /
          (sqrt(2 * CUIMG_PI) * std::pow(sigma, 5)))
    * exp(-(x * x) / (2 * sigma * sigma));
}

template <>
float gaussian_derivative<3>(float sigma, int x)
{
  return ((x * (x * x - 3 * sigma * sigma)) /
          (sqrt(2 * CUIMG_PI) * std::pow(sigma, 7)))
    * exp(-(x * x) / (2 * sigma * sigma));
}

template <>
float gaussian_derivative<4>(float sigma, int x)
{
  return ((x*x*x*x - 6 * x*x * sigma * sigma + 3 * std::pow(sigma, 4)) /
          (sqrt(2 * CUIMG_PI) * std::pow(sigma, 9)))
    * exp(-(x * x) / (2 * sigma * sigma));
}

  float gaussian_derivative(int n, float sigma, int x)
  {
    switch(n)
    {
      case 0: return gaussian_derivative<0>(sigma, x);
      case 1: return gaussian_derivative<1>(sigma, x);
      case 2: return gaussian_derivative<2>(sigma, x);
      case 3: return gaussian_derivative<3>(sigma, x);
      case 4: return gaussian_derivative<4>(sigma, x);
      default: return 0;
    }
  }


int main(int argc, char* argv[])
{
  if (argc != 2)
  {
    std::cout << "Usage: ./make_meta_gaussian out.h" << std::endl;
    return 1;
  }

  std::ofstream of(argv[1]);

  of << "// This file is generated." << std::endl;
  of << "#ifndef CUIMG_META_GAUSSIAN_H_" << std::endl;
  of << "# define CUIMG_META_GAUSSIAN_H_" << std::endl;
  of << std::endl;
  of << std::endl;
  of << "template <int N, int S> struct meta_gaussian {};"<<  std::endl;
  of << "template <typename T, int X> struct meta_kernel { static __host__ __device__ float coef() {return 0.f;} };"<<  std::endl;
  of << std::endl;
  of << std::endl;

  for (unsigned n = 0; n <= 2; n++)
  {
    of << "// " << n << " th derivative." << std::endl;
    for (unsigned s = 1; s <= 10; s++)
    {
      of << "// sigma = " << s << "." << std::endl;
      for (int x = -50; x <= 50; x++)
      {
        float res = gaussian_derivative(n, float(s), x);
        if (res != 0.f)
          of << "template <> struct meta_kernel<meta_gaussian<" << n << ", " << s << ">, " << x
            << "> { static __host__ __device__ float coef() { return " << res << "; } }; " << std::endl;
      }
      of << std::endl;
    }
  }
  of << "#endif //! CUIMG_META_GAUSSIAN_H_" << std::endl;
}