#include<stdlib.h>
#include<stdio.h>
#include<math.h>

int main(int argc,char **argv) {
	if(argc<2) {
		printf("You must provide a number of points to generate.\n");
		return 0;
	}
	FILE *fout=fopen("physics.xml","wt");
	fprintf(fout,"<system dt=\"1e-3\">\n");
	fprintf(fout,"\t<particle x=\"0.0\" y=\"0.0\" z=\"0.0\" vx=\"0.0\" vy=\"0.0\" vz=\"0.0\" mass=\"39.48\" radius=\"1e-3\"/>\n");
	int num=atoi(argv[1]);
	for(int i=0; i<num; ++i) {
		double ang=2.0*3.1415927*drand48();
		double rad=1.0+drand48();
		double vel=sqrt(39.48/rad);
		fprintf(fout,"\t<particle x=\"%f\" y=\"%f\" z=\"%f\" vx=\"%f\" vy=\"%f\" vz=\"%f\" mass=\"%f\" radius=\"%f\"/>\n",rad*cos(ang),rad*sin(ang),rad*0.1*(drand48()-0.5),-vel*sin(ang),vel*cos(ang),0.0,3e-5/num,1e-5);
	}
	fprintf(fout,"</system>\n");
	fclose(fout);
}