#include <cmath></cmath>

namespace

{

/*

				    center

				      V

	sequence

	  0   1   2 ...				     int_diameter-1

	  v   v   v ...						  v

	+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

	|<------------------- int_diameter(pixel) ----------------->|

	  |<--- int_radius(pixel) --->|

	   |<------ real_radius ----->|

	      |<- int_radius(pixel) ->|

	       |<---- real_radius --->|

	          |<-int_radius(pi) ->|

	           |<- real_radius -->|

	              |<-int_radius ->|

	               |<- real_rad ->|

	                  |<- int   ->|

	                   |<- real ->|

	                      |<-   ->|

	                       |<-  ->|

	                          |<->|

	                           |<>|

 */

void gauss_distribution_1d_(

	double *sequence, const int int_diameter /* sequence配列の長さ */

	,

	const int int_radius, const double real_radius, const double sigma /* = 0.25 : 適当な値... */

	)

{

	/* メモリクリア */

	for (int ii = 0; ii < int_diameter; ++ii) {

		sequence[ii] = 0.0;

	}

	/* 半径がゼロでも計算を可能にする、強引に... */

	const int int_radius2 = (0 < int_radius) ? int_radius : 1;

	const double real_radius2 =

		(0. < real_radius) ? real_radius : 0.000000000000001;

	/* 1pixel以下の調整

	 * -1.0の位置を(real_radius2)の位置とする */

	double dd = -1.0 * int_radius2 / real_radius2;

	/* 1pixel幅の差分 */

	const double delta = -dd / int_radius2;

	/* 開始位置 */

	const int start_pos = (int_diameter - (int_radius2 * 2 + 1)) / 2;

	/* 終了位置 */

	const int end_pos = int_diameter - start_pos;

	/* ガウス分布 */

	for (int ii = start_pos; ii < end_pos; ++ii) {

		sequence[ii] = exp(

			-(dd * dd) / (2.0 * sigma * sigma));

		dd += delta;

	}

	/* 積算 */

	dd = 0.0;

	for (int ii = start_pos; ii < end_pos; ++ii) {

		dd += sequence[ii];

	}

	/* 正規化(積算結果が1となるように割算する) */

	for (int ii = start_pos; ii < end_pos; ++ii) {

		sequence[ii] /= dd;

	}

}

}