#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "local_proto.h"


double *anderson_darling  (double *x, int n)
{
  int i;
  static double y[2];
  double sqrt2, mean = 0.0, sdx=0.0,*xcopy, fx;

  if ((xcopy = (double *) malloc (n * sizeof (double))) == NULL)
  {
      fprintf (stderr, "Memory error in anderson_darling\n");
      exit (EXIT_FAILURE);
  }

  sqrt2 = sqrt ((double) 2.0);
  y[0]=y[1]=0.0;

  for (i = 0; i < n; ++i)
  {
    xcopy[i]= x[i];
    mean += x[i];
    sdx += x[i] * x[i];
  }
  sdx = sqrt ((n * sdx - mean * mean) / (n * (n - 1.0)));
  mean /= n;

  qsort (xcopy, n, sizeof (double), dcmp);

  for (i = 0; i < n; ++i)
    xcopy[i] = (xcopy[i] - mean) / sdx;

  for (i = 0; i < n; ++i)
  {
    fx = 0.5 + normp (xcopy[i] / sqrt2) / 2.0;
    if (fx <= 1e-5)
      fx = 1e-5;

    if (fx >= .99999)
      fx = 0.99999;

    y[1] += (2.0*i+1.0)  * log(fx) + (2.0*(n-i)-1.0) * log(1-fx);
  }
  y[1]=-n-y[1]/n;
  y[0] = y[1] * (0.75 / n + 1.0 + 2.25 / (n * n));

#ifdef NOISY
  fprintf (stdout,"  TEST8  AD(N)  =%10.4f\n", y[0]);
#endif				/* NOISY */
  free(xcopy);

  return y;
}
