fractal/criticals.c

/*
 * fractal
 * Written in 2020 by Lucas
 * CC0 1.0 Universal/Public domain - No rights reserved
 *
 * To the extent possible under law, the author(s) have dedicated all
 * copyright and related and neighboring rights to this software to the
 * public domain worldwide. This software is distributed without any
 * warranty. You should have received a copy of the CC0 Public Domain
 * Dedication along with this software. If not, see
 * <http://creativecommons.org/publicdomain/zero/1.0/>.
 */
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#include "criticals.h"
#include "util.h"

#define MAX_CRITICALS 100

static size_t idx = 0;
static long double complex criticals[MAX_CRITICALS];

int
criticals_test(long double complex (*df)(long double complex),
    long double complex (*ddf)(long double complex), long double complex z,
    long double complex *crit, long niters, long double bailout,
    long double epsilon)
{
	long i;
	for (i = 0; i < niters && cabsl(z) < bailout; i++)
		z = z - df(z) / ddf(z);

	if (cabsl(df(z)) < epsilon) {
		*crit = z;
		return 1;
	}

	return 0;
}

void
criticals_add(long double complex z)
{
	size_t i;

	if (idx >= MAX_CRITICALS)
		return;
	for (i = 0; i < idx; i++)
		if (cabsl(z - criticals[i]) < 1.0e-8)
			return;

	criticals[idx++] = z;
}

size_t
criticals_size(void)
{
	return idx;
}

long double complex
criticals_get(size_t i)
{
	if (i >= idx)
		errx(1, "get_critical: index %zu out of range", i);
	return criticals[i];
}