lms.c

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/*****************************************************************************/
#include "libtpcmodel.h"
/*****************************************************************************/
/* local function definitions */
int lmsQSort(const void *par1, const void *par2);
/*****************************************************************************/
double least_median_of_squares(
  double *data,
  int n
) {
  int i, odd=1, half=floor(n/2), smallnr;
  double small, *help;
  if(fmod((double)n, 2.0)<1e-99) odd=0;
  double *halfs_data;
 
  halfs_data=(double*)malloc((half+odd) * sizeof(double)); 
 
  help=data;
  /* sort data in ascending order*/
  qsort(help, n, sizeof(double), lmsQSort); 
 
  /* if n is even number */
  for(i=0; i<half+odd; i++) {
    halfs_data[i]=data[half+i]-data[i];
  }
 
  i=smallnr=0;
  for(i=1, small=halfs_data[0]; i<half+odd; i++) {
    if(halfs_data[i]<small) {
      small=halfs_data[i];
      smallnr=i;
    }
  }
 
  return (data[half+smallnr]+data[smallnr])/2.0;
}
/*****************************************************************************/
 
/*****************************************************************************/
int lmsQSort(
  const void *par1, 
  const void *par2
) {
  if( *((double*)par1) < *((double*)par2)) return(-1);
  else if( *((double*)par1) > *((double*)par2)) return(1);
  else return(0);
}
/*****************************************************************************/
 
/*****************************************************************************/