#include <stdio.h> #include <stdlib.h> #include <math.h> #include <complex.h>// floor   /*  based on  c++ program from : [[:File:Color_complex_plot.jpg]] by  	Claudio Rocchini  gcc d.c -lm -Wall  http://en.wikipedia.org/wiki/Domain_coloring    */   const double PI = 3.1415926535897932384626433832795; const double E  = 2.7182818284590452353602874713527;    /*  complex domain coloring  Given a complex number z=re^{ i \theta},    hue represents the argument ( phase, theta ),   sat and value represents the modulus  */ int GiveHSV( double complex z, double HSVcolor[3] ) {  //The HSV, or HSB, model describes colors in terms of hue, saturation, and value (brightness).    // hue = f(argument(z))  //hue values range from .. to ..  double a = carg(z); //  while(a<0) a += 2*PI; a /= 2*PI;    // radius of z  double m = cabs(z); //   double ranges = 0;  double rangee = 1;  while(m>rangee){    ranges = rangee;    rangee *= E;       }  double k = (m-ranges)/(rangee-ranges);   // saturation = g(abs(z))  double sat = k<0.5 ? k*2: 1 - (k-0.5)*2;  sat = 1 - pow( (1-sat), 3);   sat = 0.4 + sat*0.6;   // value = h(abs(z))  double val = k<0.5 ? k*2: 1 - (k-0.5)*2;     val = 1 - val;    val = 1 - pow( (1-val), 3);     val = 0.6 + val*0.4;    HSVcolor[0]= a;  HSVcolor[1]= sat;  HSVcolor[2]= val; return 0; }      int GiveRGBfromHSV( double HSVcolor[3], unsigned char RGBcolor[3] ) {         double r,g,b;         double h; double s; double v;         h=HSVcolor[0]; // hue          s=HSVcolor[1]; //  saturation;         v = HSVcolor[2]; // = value;          if(s==0)                 r = g = b = v;         else {                 if(h==1) h = 0;                 double z = floor(h*6);                  int i = (int)z;                 double f = (h*6 - z);                 double p = v*(1-s);                 double q = v*(1-s*f);                 double t = v*(1-s*(1-f));                 switch(i){                         case 0: r=v; g=t; b=p; break;                         case 1: r=q; g=v; b=p; break;                         case 2: r=p; g=v; b=t; break;                         case 3: r=p; g=q; b=v; break;                         case 4: r=t; g=p; b=v; break;                         case 5: r=v; g=p; b=q; break;                 }         }         int c;         c = (int)(256*r); if(c>255) c = 255; RGBcolor[0] = c;         c = (int)(256*g); if(c>255) c = 255; RGBcolor[1] = c;         c = (int)(256*b); if(c>255) c = 255; RGBcolor[2] = c;   return 0; }  int GiveRGBColor( double complex z, unsigned char RGBcolor[3]) {   static double HSVcolor[3];   GiveHSV( z, HSVcolor );   GiveRGBfromHSV(HSVcolor,RGBcolor);   return 0; }  //   double complex fun(double complex c ){   return (cpow(c,2)-1)*cpow(c-2.0- I,2)/(cpow(c,2)+2+2*I);} //    int main(){         // screen (integer ) coordinate         const int dimx = 800; const int dimy = 800;         // world ( double) coordinate         const double reMin = -2; const double reMax =  2;         const double imMin = -2; const double imMax =  2;                  static unsigned char RGBcolor[3];         FILE * fp;         char *filename ="complex.ppm";         fp = fopen(filename,"wb");         fprintf(fp,"P6\n%d %d\n255\n",dimx,dimy);             int i,j;         for(j=0;j<dimy;++j){                 double im = imMax - (imMax-imMin)*j/(dimy-1);                 for(i=0;i<dimx;++i){                                     double re = reMax - (reMax-reMin)*i/(dimx-1);                         double complex z= re + im*I; //                          double complex v = fun(z); //                              GiveRGBColor( v, RGBcolor);                                                  fwrite(RGBcolor,1,3,fp);                 }         }         fclose(fp);         printf("OK - file %s saved\n", filename);          return 0; }