多层次熵算法C++实现

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这是我在项目《基于心电信号（ECG）的冠心病辅助诊断软件设计——基于多层次熵与SVM》中完成的对多层次熵算法的C++实现。

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/*   void entropy_tree_analysis(double *a,					*/
/*								int num , 					*/
/*								int template_length,		*/
/*								int depth ,					*/
/*								char* save_file_name,		*/ 
/*								float r_percentage=0.1); 	*/
/* ouput:  对序列做树分解，然后再求各层熵，结果保存在save_file_name */
/* input:  double为时间序列的数据类型,a指向时间序列的起始地址，num为序列长度，*/
/*         template_length为模板长度，depth为树分解深度，r_percentage为搜索半径的松弛系数.*/

/* 说明：为节省空间此函数会修改时间序列a里面的值，参数r_percentage用来算搜索半径，默认为10%，搜索半径为序列方差*r_percentage； */

/* This function calcuate the stand variance of the data. */
double stdvar(double * a, int num)
{
	double sum = 0, sum_2 = 0, var;

	for(int i=0; i<num; i++)
	{
		sum += a[i];
		sum_2 += a[i]*a[i];
	}
	var = sum_2/num - (sum/num)*(sum/num);
	if( var < 0 )
		throw printf( "variance is less than 0");

	return sqrt(var);
}

void tree_analysis_help(double *a, int num, double *d)
{
	int new_num = num/2;

	for ( int i = 0; i<new_num; i++ )
	{
		d[i] =  a[2*i] + a[2*i + 1] ;
		d[new_num + i] =  a[2*i] - a[2*i + 1] ;
	}
}

void entropy_tree_analysis(double *a, int num, int template_length, int depth, char* save_file_name, float r_percentage = 0.1)
{
	int num_real = num - num%( 1<<depth );
	double *_b = new double[num];
	double *b = _b;
	int start, length = num_real*2, entp_num = ( 1<<depth ) -1;
	double *entp;
	double *p_entp;
	p_entp = new double[entp_num];

	for ( int i = 0, j = 0; i<depth; i++)
	{
		if ( i == 0 )
		{
			entp = sampen(a, template_length, r_percentage * stdvar(a, num), num);
			p_entp[j] = entp[4];
			j++;
			if ( entp != NULL )	{delete[] entp;	entp = NULL;}
		}
		else
		{
			for ( start = 0, length/=2; start < num_real; start += length )
			{
				tree_analysis_help( a + start, length, b + start );
			}

			for ( start = 0; start < num_real; start += length/2 )
			{
				entp = sampen( b + start, template_length, r_percentage * stdvar( b + start, length/2 ), length/2 );
				p_entp[j] = entp[4];
				j++;
				if ( entp != NULL )	{delete[] entp;	entp = NULL;}
			}
			double *temp = a;
			a = b;
			b = temp;
		}
	}

	FILE * outf;
	outf = fopen(save_file_name, "wb");
	fwrite( &entp_num, sizeof(int), 1, outf);
	fwrite( p_entp, sizeof(double), entp_num, outf );
	fclose( outf );

	delete[] p_entp;
	delete[] _b;
}