Initial import
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361
julia.c
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361
julia.c
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/*
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* fractal
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* Written in 2020 by Lucas
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* CC0 1.0 Universal/Public domain - No rights reserved
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*
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* To the extent possible under law, the author(s) have dedicated all
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* copyright and related and neighboring rights to this software to the
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* public domain worldwide. This software is distributed without any
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* warranty. You should have received a copy of the CC0 Public Domain
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* Dedication along with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include <complex.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <math.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "criticals.h"
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#include "palette.h"
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#include "pnmout.h"
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#include "util.h"
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#include "fun.h"
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struct color contour_color = { 0 };
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static long double bailout = 1e100,
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epsilon = 1e-8,
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sec_w = 4.0,
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contour = 0.0005L;
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static unsigned long niters = 250;
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static void
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print_critical_points(void)
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{
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long double complex z;
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size_t i, n;
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n = ncriticals();
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fprintf(stderr, "Critical points:\n");
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for (i = 0; i < n; i++) {
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z = get_critical(i);
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fprintf(stderr, "%4zu. (%.20Lf, %.20Lf)\n", i, creall(z),
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cimagl(z));
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}
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}
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static int
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tends_to_critical(long double complex z, long double *t)
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{
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long double d;
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size_t i, n;
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n = ncriticals();
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for (i = 0; i < n; i++) {
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d = cabsl(z - get_critical(i));
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if (d < epsilon) {
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*t = d;
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return 1;
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}
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}
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return 0;
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}
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static long
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iterate(long double complex z, long double complex c, long double *rit)
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{
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long double complex dz = 1.0L;
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long double t;
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unsigned long ci, i;
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for (i = 0; i < niters && cabsl(z) < bailout; i++) {
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dz = df(z) * dz;
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z = f(z) + c;
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if (tends_to_critical(z, &t)) {
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*rit = logl(logl(t) / logl(epsilon)) / logl(2.0L);
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return fabsl(logl(t)) * t < sec_w * contour * cabsl(dz)
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? -1 : i;
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}
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}
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t = cabsl(z);
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if (t >= bailout) {
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*rit = logl(logl(t) / logl(bailout)) / logl(2.0L);
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return fabsl(logl(t)) * t < sec_w * contour * cabsl(dz)
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? -1 : i;
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}
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return -1;
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}
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static long
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fast_iterate(long double complex z, long double complex c, long double *rit)
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{
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long double t;
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unsigned long ci, i;
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for (i = 0; i < niters && cabsl(z) < bailout; i++) {
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z = f(z) + c;
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if (tends_to_critical(z, &t)) {
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*rit = logl(logl(t) / logl(epsilon)) / logl(2.0L);
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return i;
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}
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}
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t = cabsl(z);
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if (t >= bailout) {
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*rit = logl(logl(t) / logl(bailout)) / logl(2.0L);
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return i;
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}
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return -1;
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}
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static void
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usage(void)
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{
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fprintf(stderr, "Usage: %s julia [-L] [-x julia_x] [-y julia_y]\n"
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" [-n niters] [-h height] [-w width] [-z zoom]\n"
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" [-a center_x] [-b center_y] [-l light_intensity]\n"
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" [-d density] [-c contour]\n",
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xgetprogname());
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exit(1);
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}
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int
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julia_main(int argc, char *argv[])
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{
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struct color *palette;
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struct {
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long long it;
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long double rit;
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} *rescache;
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char *end;
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struct color color;
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long double complex crit, julia, z;
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long double julia_x = 0.0,
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julia_y = 0.0,
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cen_x = 0.0,
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cen_y = 0.0,
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density = 28.3L,
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light_intensity = 84.3L,
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displacement = 0,
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zoom = 1.0,
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light, light_x, light_y, light_z, rit, sec_h, zx, zy;
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intmax_t v;
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long long it, idx, ritnum;
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unsigned int palette_size = 720,
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width = 640,
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height = 400,
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i, j;
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int ch, do_light = 0;
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while ((ch = getopt(argc, argv, "a:b:c:d:h:Ll:n:w:x:y:z:")) != -1)
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switch (ch) {
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case 'a':
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errno = 0;
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cen_x = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-a: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'b':
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errno = 0;
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cen_y = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-b: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'c':
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errno = 0;
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contour = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0
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|| contour <= 0) {
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fprintf(stderr, "-c: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'd':
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errno = 0;
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density = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-d: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'h':
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errno = 0;
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v = strtoimax(optarg, &end, 0);
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if (end == optarg || *end != '\0' || errno != 0 ||
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v <= 0 || v >= 65536) {
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fprintf(stderr, "-h: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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height = (unsigned int)v + 1;
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break;
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case 'L':
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do_light = 1;
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break;
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case 'l':
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errno = 0;
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light_intensity = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-l: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'n':
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errno = 0;
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v = strtoimax(optarg, &end, 0);
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if (end == optarg || *end != '\0' || errno != 0 ||
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v <= 0 || v >= ULONG_MAX) {
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fprintf(stderr, "-n: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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niters = (unsigned long)v;
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break;
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case 'w':
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errno = 0;
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v = strtoimax(optarg, &end, 0);
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if (end == optarg || *end != '\0' || errno != 0 ||
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v <= 0 || v >= 65536) {
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fprintf(stderr, "-w: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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width = (unsigned int)v + 1;
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break;
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case 'x':
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errno = 0;
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julia_x = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-x: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'y':
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errno = 0;
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julia_y = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0) {
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fprintf(stderr, "-y: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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case 'z':
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errno = 0;
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zoom = strtold(optarg, &end);
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if (end == optarg || *end != '\0' || errno != 0
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|| zoom <= 0) {
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fprintf(stderr, "-z: invalid value \"%s\"",
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optarg);
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exit(1);
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}
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break;
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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if (argc > 1)
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usage();
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palette = palette_gen(palette_size);
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if ((rescache = malloc(sizeof(*rescache) * width * height)) == NULL) {
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fprintf(stderr, "out of memory\n");
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exit(1);
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}
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if (do_light) {
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long double angle_xy, angle_z;
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angle_xy = drand48() * 2.0L * 3.14159265358979323846L;
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angle_z = (0.2L + 0.6L * drand48()) * 3.14159265358979323846L;
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light_x = cosl(angle_xy) * sinl(angle_z);
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light_y = sinl(angle_xy) * sinl(angle_z);
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light_z = cosl(angle_z);
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}
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sec_h = sec_w * height / (long double)width;
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julia = julia_x + I * julia_y;
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for (i = 0; i < height; i++) {
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zy = cen_y + (0.5 - i / (long double)height) * sec_h;
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for (j = 0; j < width; j++) {
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zx = cen_x + (j / (long double)width - 0.5L) * sec_w;
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z = zx + I * zy;
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if (behaves_critical(df, ddf, z, &crit, bailout,
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epsilon))
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add_critical_point(crit);
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}
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}
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print_critical_points();
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sec_w /= zoom; sec_h /= zoom;
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for (i = 0; i < height; i++) {
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zy = cen_y + (0.5L - i / (long double)height) * sec_h;
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for (j = 0; j < width; j++) {
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zx = cen_x + (j / (long double)width - 0.5L) * sec_w;
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z = zx + I * zy;
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it = iterate(z, julia, &rit);
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rescache[i * width + j].it = it;
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rescache[i * width + j].rit = rit;
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}
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}
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pnmout_header(stdout, width - 1, height - 1);
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for (i = 0; i < height - 1; i++) {
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for (j = 0; j < width - 1; j++) {
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it = rescache[i * width + j].it;
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rit = rescache[i * width + j].rit;
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if (it < 0)
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color = contour_color;
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else {
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ritnum = (it - rit) * density;
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if (do_light) {
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long double lxrn, lyrn, l, lx, ly, lz;
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lxrn = rescache[i * width + j + 1].it
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- rescache[i * width + j + 1].rit;
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lyrn = rescache[(i + 1) * width + j].it
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- rescache[(i + 1) * width + j].rit;
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lx = -sec_h * (lxrn - it + rit);
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ly = sec_w * (lyrn - it + rit);
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lz = sec_w * sec_h;
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l = sqrtl(lx * lx + ly * ly + lz * lz);
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light = (light_x * lx + light_y * ly
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+ light_z * lz) / l;
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ritnum += light * light_intensity;
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}
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idx = (long long)ritnum
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+ 1000000 * palette_size + displacement;
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color = palette[idx % palette_size
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+ (idx < 0 ? palette_size : 0)];
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}
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pnmout_pixel(stdout, color);
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}
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}
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free(rescache);
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free(palette);
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return !(fflush(stdout) == 0);
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}
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