/*
 *  Chi-square test
 */

#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include "config.h"
#include "gsl_types.h"
#include "gsl_rng.h"
#include "gsl_randist.h"

#pragma lib "libsys.a"
#pragma lib "libspecfunc.a"
#pragma lib "librng.a"
#pragma lib "librandist.a"




int chidf; 
double chisq, probchisq;
Biobuf bin;
int help=0;
int verbose=0;
int proportions=0;
int help=0;

void intro(void);
int readparams();
void confid_int(void);
void t_test(void);
void t_test2(void);
void chi_square(void);
void results(void);


int
readparams(void)
// reads n1, N1, n2, N2 for two binomial samples, or, if -p, p1, N1, p2, N2 
{
	char *buf, *av[256], first;
	int i, j, n;
	Binit(&bin, 0, OREAD);

	n=0;
	while(n==0){
		if((buf = Brdstr(&bin, '\n', 1)) == nil) return 0;			// nothing to read
		first=buf[0];
//				print("first==%c\n", first);
		n=tokenize(buf, av, 4);
		if(n!=0){
			// skip comment lines
			if((first=='#') || (first=='>')){
//				print("comments\n");
				n=0;
			}
		}
		else{
		// skip whitespace lines
//			print("whitespace\n");	
		}
	}	// ends up with n > 0
	chisq=atof(av[0]);
	chidf=atof(av[1]);
	return 0;
} /*  readparams  */


void
chi_square(void) {
  probchisq=gsl_ran_chisq_pdf(chisq, chidf);
} /*  chi_square  */

void
intro(void) {
  print("Chi-square test\n");
  print("please, give me chisq, and df, ");
  print("whitespace separated on a single line\n");
} /*  intro  */

void
results(void) {
  print("\n\nChi-square test\n\n");
  print("chi-square = %f (has chi-squared-distribution with %d degrees of freedom)\n", chisq, chidf);
  print("Associated probability P(x, df) = %e \n", probchisq);

} /*  results  */



void
main(int argc, char *argv[])
{
	ARGBEGIN{
	case 'h':
		help = 1;
		break;
	case 'v':
		verbose = 1;
		break;
	}ARGEND

	if(verbose) intro();
	readparams();
	chi_square();
	results();
} /*  main  */