void hyperbolic_coordinates() {
	const double DIMX = 800; const double DIMY = 800;
	const double B    = 64;  const double S    = 128;
	const double miu  = -2;  const double mau  = 2;
	const double miv  = 0;   const double mav  = 8;
	const int N = 24;        const int M = 1024;

	FILE * fp = fopen("c:\\temp\\hyperbolic_coordinates.svg","w");

	fprintf(fp,
		"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\"?>\n"
		"<svg\n"
		"xmlns:svg=\"http://www.w3.org/2000/svg\"\n"
		"xmlns=\"http://www.w3.org/2000/svg\"\n"
		"version=\"1.0\"\n"
		"width=\"%g\"\n"
		"height=\"%g\"\n"
		"id=\"rocco\">\n"
		,DIMX,DIMY
	);
	fprintf(fp,"<g id=\"edge_layer1\" style=\"fill:none;stroke:#800000;stroke-width:1.5;stroke-opacity:1\">\n" );

	int i,j;
	for(j=0;j<N;++j) {
		const double v = miv + (mav-miv)*double(j)/(N-1);
		fprintf(fp, "<path d=\"" );
		bool first = true;
		for(i=0;i<M;++i) {
			const double u = miu + (mau-miu)*double(i)/(M-1);
			double x = v*exp( u); double y = v*exp(-u);
			x =       x*S+B;      y = DIMY-(y*S+B);
			if(x>=B && x<=DIMX-B && y>=B && y<=DIMY-B ) {
				if(first) fprintf(fp,"M ");
				else      fprintf(fp,"L ");
				fprintf(fp,"%g %g ",x,y);
				first = false;
			}
		}
		fprintf(fp,"\"/>\n");
	}

	fprintf(fp,
		"</g>\n"
		"<g id=\"edge_layer2\" style=\"fill:none;stroke:#000080;stroke-width:1.5;stroke-opacity:1\">\n"
	);

	for(i=0;i<N ;++i) {
		const double u = miu + (mau-miu)*double(i)/(N-1);
		fprintf(fp, "<path d=\"");
		bool first = true;
		for(j=0;j<M;++j)	{
			const double v = miv + (mav-miv)*double(j)/(M-1);
			double x = v*exp( u); double y = v*exp(-u);
			x =       x*S+B;      y = DIMY-(y*S+B);
			if(x>=B && x<=DIMX-B && y>=B && y<=DIMY-B ) {
				if(first) fprintf(fp,"M ");
				else      fprintf(fp,"L ");
				fprintf(fp,"%g %g ",x,y);
				first = false;
			}
		}
		fprintf(fp,"\"/>\n");
	}

	fprintf(fp,
		"</g>\n"
		"</svg>\n"
	);

	fclose(fp);
}