statistics.c

来自「一个开源的网络开发库ACE」· C语言 代码 · 共 50 行

/* statistics.c,v 1.3 2000/09/22 19:30:37 brunsch Exp */
/**************************************************************************
 *									  *
 * 		 Copyright (C) 1995 Silicon Graphics, Inc.		  *
 *									  *
 *  These coded instructions, statements, and computer programs were	  *
 *  developed by SGI for public use.  If any changes are made to this code*
 *  please try to get the changes back to the author.  Feel free to make  *
 *  modifications and changes to the code and release it.		  *
 *									  *
 **************************************************************************/

/* FUZZ: disable check_for_math_include */
#include <math.h>
#include <stdlib.h>
#include "sysdep.h"
#include "bench.h"


double
mean(const double sum, const int n)
{
  if (n)
    {
      return(sum / n);
    }
  else
    {
      return(0);
    }
}


double
variance(const double sum, const double sumofsquares, const int n)
{
	double	meanofsum;

	meanofsum = mean(sum, n);

	return (mean(sumofsquares,n) - (meanofsum * meanofsum));
}


double
stddev(const double sum, const double sumofsquares, const int n)
{
	return(sqrt(fabs(variance(sum, sumofsquares, n))));
}