菲根鲍姆图（费根鲍姆图，Feigenbaum）的制作

这里采用了Linux下的gcc编译C,并使用了SDL.
这个程序可以作任意精度。

/* fgbm 1.0 

  fgbm 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, or (at your option)
  any later version.
  fgbm 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 fgbm; see the file COPYING.  If not, write to
  the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  Boston, MA 02111-1307, USA.
 
  Contact Info: 
     [e-mail]
*/
//This is a programme to draw fygenbm pic.
//x[0]=Begin;
//x[i]=r*x[i-1]*(1-x[i-1]);
//draw (y) r from 0 to 4 
//draw (x) x[i] i for 1000 to 1999
//The programme is designed by Vesuvius.
//[e-mail]
//
//You need to pass number about where the r x start and end 
//and the step long
//
//The Library I use is SDL.
//

#include
#include

#define Begin 0.7//The begin number of x[]

SDL_Surface *screen;//The screen pointer on which we draw.

SDL_Surface *initSDL(int w,int y)//start the SDL and create a screen.
{
	SDL_Surface *screen;

	SDL_Init(SDL_INIT_VIDEO);
	screen=SDL_SetVideoMode(w,y,8,SDL_SWSURFACE);
	return screen;
}

void drawPoint(SDL_Surface *surface,int x,int y)//draw a point on screen
{
	Uint32 yellow;
	int bpp;
	Uint8 *p;

	yellow=SDL_MapRGB(surface->format,0xff,0xff,0x00);
	if(SDL_MUSTLOCK(surface)){
		if(SDL_LockSurface(surface)<0){
			fprintf(stderr,"Can't lock screen: %s\n",SDL_GetError());
			return;
		}
	}
	
	bpp=surface->format->BytesPerPixel;
	p=(Uint8 *)surface->pixels+y*surface->pitch+x*bpp;
	switch(bpp){
		case 1:
			*p=yellow;
			break;
		case 2:
			*(Uint16 *)p=yellow;
			break;
		case 3:
			if(SDL_BYTEORDER==SDL_BIG_ENDIAN){
				p[0]=(yellow>>16) &0xff;
				p[1]=(yellow>>8)& 0xff;
				p[2]=yellow & 0xff;
			}else{
				p[0]=yellow&0xff;
				p[1]=(yellow>>8)&0xff;
				p[2]=(yellow>>16)&0xff;
			}
			break;
		case 4:
			*(Uint32 *)p=yellow;
			break;
	}
	if(SDL_MUSTLOCK(surface)){
		SDL_UnlockSurface(surface);
	}
	SDL_UpdateRect(surface,x,y,1,1);		
}

void fgbm(double startr,double endr,double stepr,double startx,double endx,double stepx)//The fun we design most
{
	double r,x[2000];
	int j;
	
	for(r=startr;r<=endr;r+=stepr){
		x[0]=Begin;
		for(j=1;j<2000;j++){
			x[j]=r*x[j-1]*(1-x[j-1]);//create the number
			//draw the number is the screen
			if(j>999 && x[j]>=startx && x[j]<=endx) drawPoint(screen,(int)((x[j]-startx)/stepx+1),(int)((r-startr)/stepr+1));
		}
	}
}


int main(int argv,char *argc[])
{
	double startr,endr,stepr,startx,endx,stepx;
	
	sscanf(argc[1],"%lf",&startr);
	sscanf(argc[2],"%lf",&endr);
	sscanf(argc[3],"%lf",&stepr);
	sscanf(argc[4],"%lf",&startx);
	sscanf(argc[5],"%lf",&endx);
	sscanf(argc[6],"%lf",&stepx);

	screen=initSDL((int)((endx-startx)/stepx+2),(int)((endr-startr)/stepr+2));
	fgbm(startr,endr,stepr,startx,endx,stepx);
	SDL_SaveBMP(screen,"a.bmp");
	getchar();
	SDL_Quit();
	return 0;
}

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