N_tools.c

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/*****************************************************************************
*
* MODULE:       Grass PDE Numerical Library
* AUTHOR(S):    Soeren Gebbert, Berlin (GER) Dec 2006
*               soerengebbert <at> gmx <dot> de
*               
* PURPOSE:      Array managment functions 
*               part of the gpde library
*
* COPYRIGHT:    (C) 2000 by the GRASS Development Team
*
*               This program is free software under the GNU General Public
*               License (>=v2). Read the file COPYING that comes with GRASS
*               for details.
*
*****************************************************************************/

#include "grass/N_pde.h"
#include "grass/glocale.h"
#include <math.h>


double N_calc_arith_mean(double a, double b)
{
    double val = 0;

    val = (a + b) / 2.0;

    return val;
}

double N_calc_arith_mean_n(double *a, int size)
{
    double val = 0.0;

    int i;

    for (i = 0; i < size; i++)
        val += a[i];

    val = (val / (double)size);

    return val;
}


double N_calc_geom_mean(double a, double b)
{
    double val = 0;

    val = sqrt(a * b);

    return val;
}

double N_calc_geom_mean_n(double *a, int size)
{
    double val = 1;

    int i;

    for (i = 0; i < size; i++)
        val *= a[i];

    val = (double)pow((long double)val, (long double)1.0 / (long double)size);

    return val;
}


double N_calc_harmonic_mean(double a, double b)
{
    double val = 0.0;

    if ((a + b) != 0)
        val = 2.0 * (a * b) / (a + b);

    return val;
}

double N_calc_harmonic_mean_n(double *a, int size)
{
    double val = 0;

    int i;

    for (i = 0; i < size; i++)
        if (a[i] != 0.0)
            val += 1.0 / a[i];
        else
            return 0.0;

    if (val == 0.0)
        return 0.0;
    else
        val = 1.0 / (1.0 / (double)size * val);

    return val;
}


double N_calc_quad_mean(double a, double b)
{
    double val = 0.0;

    val = sqrt((a * a + b * b) / 2.0);

    return val;
}

double N_calc_quad_mean_n(double *a, int size)
{
    double val = 0;

    int i;

    for (i = 0; i < size; i++)
        val += a[i] * a[i];

    val = sqrt(val / (double)size);

    return val;
}