147 lines
4.6 KiB
C
147 lines
4.6 KiB
C
#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <time.h>
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#include "colors.h"
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#include "doubledouble.h"
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double get_time() {
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struct timespec ts; clock_gettime(CLOCK_REALTIME, &ts);
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return ts.tv_sec * 1000.0 + ts.tv_nsec / 1000000.0;
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}
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int main(int argc, char **argv) {
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unsigned width, height;
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DoubleDouble magn;
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if (argc <= 1) {
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width = 1024;
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height = width;
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magn = dd_new(4e5, 0);
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} else if (argc == 3) {
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width = atoi(argv[1]);
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height = width;
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magn = dd_new(strtod(argv[2], NULL), 0);
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} else {
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fprintf(stderr, "usage: %s <size> <magnification>\n", argv[0]);
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return 1;
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}
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DoubleDouble temp1;
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double eps = 1e-17;
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double Q1LOG2 = 1.44269504088896340735992468100189213742664595415299;
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double LOG2 = 0.69314718055994530941723212145817656807550013436026;
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unsigned int x, y;
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DoubleDouble centerx, centery;
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centerx = dd_new(-0.7436438870371587, -3.628952515063387E-17);
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centery = dd_new(0.13182590420531198, -1.2892807754956678E-17);
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double bailout = 128; // with a smaller value there are lines on magn=1
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double logLogBailout = log(log(bailout));
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int foundperiods = 0;
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long maxiter = 50000;
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/*// maxiter = width * sqrt(magn);
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temp1 = dd_sqrt(magn);
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unsigned long maxiter = width * dd_get_ui(temp1);*/
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DoubleDouble x2, y2, x0d, y1d;
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// x0d = 4 / magn / width;
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x0d = dd_ui_div(4, magn);
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x0d = dd_div_ui(x0d, width);
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// x2 = -2 / magn + centerx;
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x2 = dd_si_div(-2, magn);
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x2 = dd_add(x2, centerx);
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// y1d = -4 / magn / width;
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y1d = dd_si_div(-4, magn);
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y1d = dd_div_ui(y1d, width);
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// y2 = 2 / magn * height / width + centery;
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y2 = dd_ui_div(2, magn);
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temp1 = dd_new(height, 0);
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temp1 = dd_div_ui(temp1, width);
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y2 = dd_mul(y2, temp1);
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y2 = dd_add(y2, centery);
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DoubleDouble px, py, zx, zy, xx, yy;
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double hx, hy, d;
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double tbeg = get_time();
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// write out image header
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printf("P6 %d %d 255\n", width, height);
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for (y = 0; y < height; y++) {
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fprintf(stderr, "\r%.2f%%", (float)(y+1)/(height)*100);
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for (x = 0; x < width; x++) {
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//px = x*x0d + x2;
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px = dd_mul_ui(x0d, x);
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px = dd_add(px, x2);
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//py = y*y1d + y2;
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py = dd_mul_ui(y1d, y);
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py = dd_add(py, y2);
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// no Main bulb or Cardoid check to be faster
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zx = dd_new(px.hi, px.lo);
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zy = dd_new(py.hi, py.lo);
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unsigned long i;
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bool inside = true;
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int check = 3;
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int whenupdate = 10;
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hx = 0;
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hy = 0;
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for (i = 1; i <= maxiter; i++) {
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//xx = zx * zx;
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xx = dd_sqr(zx);
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//yy = zy * zy;
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yy = dd_sqr(zy);
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//if (xx + yy > bailout) {
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if (xx.hi + yy.hi > bailout) {
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inside = false;
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break;
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}
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// iterate
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//zy = 2 * zx * zy + py;
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//zx = dd_mul_ui(zx, 2);
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//zy = dd_mul(zx, zy);
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zy = dd_add(dd_mul2(zx, zy), py);
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//zx = xx - yy + px;
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zx = dd_add(dd_sub(xx, yy), px);
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// period checking
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d = zx.hi - hx;
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if (d > 0.0 ? d < eps : d > -eps) {
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d = zy.hi - hy;
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if (d > 0.0 ? d < eps : d > -eps) {
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// Period found.
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foundperiods++;
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break;
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}
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}
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if ((i & check) == 0) {
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if (--whenupdate == 0) {
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whenupdate = 10;
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check <<= 1;
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check++;
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}
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// period = 0;
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hx = zx.hi;
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hy = zy.hi;
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}
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}
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if (inside) {
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const char black[3] = {};
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fwrite(black, 1, 3, stdout);
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} else {
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double r = sqrt(zx.hi*zx.hi + zy.hi*zy.hi);
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double c = i - 1.28 + (logLogBailout - log(log(r))) * Q1LOG2;
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int idx = fmod((log(c/64+1)/LOG2+0.45), 1)*(GRADIENTLENGTH-1) + 0.5;
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fwrite(&colors[idx], 1, 3, stdout);
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}
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}
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}
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double tend = get_time();
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fprintf(stderr, "\nElapsed time: %.2f ms\n", tend-tbeg);
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//fprintf(stderr, "\n%d periods found\n", foundperiods);
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return 0;
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}
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