/* -*-C-*-
 ********************************************************************************
 *
 * File:         measure.h
 * Description:  Statistics for a group of single measurements
 * Author:       Mark Seaman, SW Productivity
 *
 * (c) Copyright 1987, Hewlett-Packard Company.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 *
 ********************************************************************************
 */

#ifndef MEASURE_H
#define MEASURE_H

/*
----------------------------------------------------------------------
              I n c l u d e s
----------------------------------------------------------------------
*/

#include <cmath>

/*
----------------------------------------------------------------------
              T y p e s
----------------------------------------------------------------------
*/

typedef struct
{
  long num_samples;
  float sum_of_samples;
  float sum_of_squares;
} MEASUREMENT;

/*
----------------------------------------------------------------------
              M a c r o s
----------------------------------------------------------------------
*/

/**********************************************************************
 * add_sample
 *
 * Add one more sample to a measurement.
 **********************************************************************/

#define ADD_SAMPLE(m, s)           \
  (m.sum_of_samples += (float)(s), \
   m.sum_of_squares += (float)(s) * (float)(s), ++m.num_samples)

/**********************************************************************
 * mean
 *
 * Return the mean value of the measurement.
 **********************************************************************/

#define MEAN(m) \
  ((m).num_samples ? ((float)((m).sum_of_samples / (m).num_samples)) : 0)

/**********************************************************************
 * new_measurement
 *
 * Initialize a record to hold a measurement of a group of individual
 * samples.
 **********************************************************************/

#define new_measurement(m) \
  ((m).num_samples = 0, (m).sum_of_samples = 0, (m).sum_of_squares = 0)

/**********************************************************************
 * number_of_samples
 *
 * Return the number of samples in a measurement.
 **********************************************************************/

#define number_of_samples(m)  \
((m).num_samples)

/**********************************************************************
 * standard_deviation
 *
 * Return the standard deviation of the measurement.
 **********************************************************************/

#define standard_deviation(m)                                \
((float) sqrt (VARIANCE (m)))

/**********************************************************************
 * variance
 *
 * Return the variance of the measurement.
 **********************************************************************/

#define VARIANCE(m)                                           \
  (((m).num_samples > 1)                                      \
       ? ((float)(((m).num_samples * (m).sum_of_squares -     \
                   (m).sum_of_samples * (m).sum_of_samples) / \
                  (((m).num_samples - 1) * (m).num_samples))) \
       : 0)

/**********************************************************************
 * print_summary
 *
 * Summarize a MEASUREMENT record.
 **********************************************************************/

#define print_summary(string, measure)                             \
  cprintf("\t%-20s \tn = %d, \tm = %4.2f, \ts = %4.2f\n ", string, \
          number_of_samples(measure), MEAN(measure),               \
          standard_deviation(measure))
#endif