variance.h

来自「g729 coding ipaddressing」· C头文件 代码 · 共 52 行

/**************************************************************************
*
* ROUTINE
*				variance
*
* FUNCTION
*
*				calculates variance of the input array
*
* SYNOPSIS
*				subroutine variance(arr, no, var, avg)
*
*	formal
*
*						data	I/O
*		name			type	type	function
*		-------------------------------------------------------------------
*		arr 			float	i		input data array
*		no				int 	i		number of elements in array
*		var 			float	o		variance
*		avg 			real	i/o 	average
*
***************************************************************************
*
* DESCRIPTION
*
*
***************************************************************************
*
* CALLED BY
*
*		smoothcbgain   smoothtau
*
* CALLS
*
*
*
**************************************************************************/

static void variance(float arr[], int no, float *var, float *avg)
{
  int i;
  float sum, sum2;

  for (sum = 0.0, i = 0; i < no; i++)
	sum += arr[i];
  *avg = sum / no;
  for (sum2 = 0.0, i = 0; i < no; i++)
	sum2 += (*avg - arr[i]) * (*avg - arr[i]);
  *var = sum2 / (no - 1);
}