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/*
This file is part of GNUnet
(C) 2008--2012 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
#include <gnunet/platform.h>
#include <gnunet/gnunet_common.h>
struct SDHandle
{
/**
* Squared sum of data values
*/
unsigned long long sqsum;
/**
* Sum of the data values
*/
unsigned long sum;
/**
* The average of data amounts
*/
unsigned int avg;
/**
* The variance
*/
unsigned int vr;
/**
* Number of data values
*/
unsigned int cnt;
};
struct SDHandle *
GNUNET_TESTBED_SD_init ()
{
return GNUNET_malloc (sizeof (struct SDHandle));
}
void
GNUNET_TESTBED_SD_destroy (struct SDHandle *h)
{
GNUNET_free (h);
}
void
GNUNET_TESTBED_SD_add_data (struct SDHandle *h, unsigned int amount)
{
unsigned long sqavg;
h->sum += amount;
h->cnt++;
h->sqsum += ((unsigned long) amount) * ((unsigned long) amount);
h->avg = h->sum / h->cnt;
sqavg = h->avg * h->avg;
h->vr = (h->sqsum / h->cnt) - sqavg;
}
/**
* Returns the factor by which the given amount differs from the standard deviation
*
* @param h the SDhandle
* @param amount the value for which the deviation is returned
* @return the deviation from the average; GNUNET_SYSERR if the deviation cannot
* be calculated
*/
int
GNUNET_TESTBED_SD_deviation_factor (struct SDHandle *h, unsigned int amount)
{
unsigned long diff;
unsigned int n;
if (h->cnt < 2)
return GNUNET_SYSERR;
if (amount > h->avg)
diff = amount - h->avg;
else
diff = h->avg - amount;
diff *= diff;
for (n = 1; n < 4; n++)
if (diff < (n * n * h->vr))
break;
return n;
}
int
main ()
{
struct SDHandle * h = GNUNET_TESTBED_SD_init ();
GNUNET_TESTBED_SD_add_data (h, 40);
GNUNET_TESTBED_SD_add_data (h, 30);
GNUNET_TESTBED_SD_add_data (h, 40);
GNUNET_TESTBED_SD_add_data (h, 10);
GNUNET_TESTBED_SD_add_data (h, 30);
printf ("Average: %d\n", h->avg);
printf ("Variance: %d\n", h->vr);
printf ("Standard Deviation: %d\n", (int) sqrt (h->vr));
printf ("Deviation factor: %d\n", GNUNET_TESTBED_SD_deviation (h, 40));
GNUNET_TESTBED_SD_destroy (h);
return 0;
}
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