RandomNorm.nxc

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/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 4; tab-width: 4 -*- */
/*
    RandomNorm.nxc
    Copyright (C) 2008 Naba Kumar   <naba@gnome.org>
                       Daniele Benedettelli   <danielebenedettelli@gmail.com>

    This program 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 2 of the License, or
    (at your option) any later version.

    This program 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 this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

/* Normally distributed random numbers with mean 0 and variance 1, scaled by
 * 100 to fit in integer. 256 samples.
 */

#ifndef __RANDOM_NORM_H_
#define __RANDOM_NORM_H_

int nRandSamples[] = {
9, -95, -118, 27, -148, 0, 114, 39, -104, 208, 196, 22, -5, 0, -113, -126,
33, -11, 131, 50, -40, 175, -140, 292, -73, 68, -8, -46, -118, 95, -32, 79,
164, 138, 41, 16, -48, -32, -70, 20, -30, -169, 26, 64, -36, -76, -81, 201,
-80, -61, 0, -39, -108, 23, -59, -6, 35, 153, -15, -112, -9, 32, 151, -52,
-38, 28, 24, -24, -216, -12, -49, -2, -18, 133, 10, 77, -58, -240, -189, -36,
98, 98, 50, 131, 2, 0, -57, 108, -185, 30, -12, 43, 48, 89, 22, 21,
-63, -14, -6, 23, -58, 1, -86, -136, 174, -27, -97, 38, -178, 51, -80, 141,
-43, 49, 172, -112, 79, 64, 101, 23, -62, -242, 4, 152, 13, -201, 158, 60,
47, -66, 19, -70, 9, -125, 56, 11, -52, 90, -161, 167, 49, -77, -199, 91,
52, 203, -81, 26, -23, 45, 59, -20, 4, 32, -161, -4, -101, 118, 218, 47,
19, 114, 17, -146, -87, 26, 93, -102, 101, -18, 79, 59, 27, -28, -62, 175,
62, 19, 277, -87, -99, 33, 29, 131, -43, -88, -68, -31, -79, -120, 93, -121,
-59, -99, 35, -72, 56, 149, 37, -5, 32, 53, 11, -13, -136, 66, -185, -62,
138, 0, -8, 147, 41, -160, 82, -128, 59, 80, 106, 4, -196, 23, 111, -91,
-7, 45, 134, 78, 185, 44, -17, -41, 16, 100, 93, -20, -140, 113, 39, 102,
4, -72, -91, 183, 113, -191, 73, -26, -67, -91, -79, -217, 59, 12, 69, -117,
};

int lastNrandIndex = 0;

int RandomNorm(int scale)
{
    lastNrandIndex++;
    if (lastNrandIndex > 255)
        lastNrandIndex = 0;
    return (nRandSamples[lastNrandIndex] * scale) / 100;
}

long RandomNorm2(int scale)
{
   long nr = -600;
   for (int i = 0; i < 12; i++)
   {
       nr += Random(100);
   }
   return ((nr * scale)/100);
}

long RandomNorm3(int scale, int precision)
{
   int iter = precision * 12;
   long s;
   long nr = (-iter * 100)/2;
   for (int i = 0; i < iter; i++)
   {
       nr += Random(100);
   }
   s = (10000 * iter)/12;
   s = Sqrt(s);
   return ((nr * scale)/s);
}

/* #define ENABLE_TEST */

#ifdef ENABLE_TEST

/* return maximum value in array */
int ArrayMax(long v[])
{
    int len = ArrayLen(v);
    int max = 0;
    for(int i = 0; i < len; i++)
    {
        if (v[i] > max) max = v[i];
    }
    return max;
}

#define HIST 30
#define SAMPLES 5000
void TestRandomNorm ()
{
    long r;
    long stat[HIST];
    int progressbar, zone;
    int i, x, w, h, max;

    TextOut(0,LCD_LINE1,"Normal Samples");
    for (i = 0; i < SAMPLES; i++)
    {
        progressbar = (100 * i) / SAMPLES;
        LineOut(0, LCD_LINE2 + 4, progressbar, LCD_LINE2 + 4);
        LineOut(0, LCD_LINE2 + 3, progressbar, LCD_LINE2 + 3);
        r = RandomNorm3(100,2);

        /* build histogram */
        for (zone = 0; zone < HIST; zone++)
        {
            /* 3-sigma confidence */
            if (-300 + zone * 600 / HIST <= r & r < -300 + (zone + 1) * 600 / HIST)
                stat[zone]++;
        }
    }

    ClearScreen();
    max = ArrayMax(stat);
    w = 100/HIST - 1;
    for (zone = 0; zone < HIST; zone++)
    {
        x = (100 * zone)/HIST;
        h = (63 * stat[zone])/max;
        RectOut(x, 0, w, h);
    }
    while(true);
}
/*
task main()
{
    TestRandomNorm();
}
*/
#endif /* ENABLE_TEST */
#endif /* __RANDOM_NORM_H_ */