#include <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;
	}
}
}