/* nag_2_sample_t_test (g07cac) Example Program.
 *
 * Copyright 1996 Numerical Algorithms Group.
 *
 * Mark 4, 1996.
 *
 * Mark 6 revised, 2000.
 */

#include <nag.h>
#include <nagx04.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagg07.h>

int main(int argc, char *argv[])
{
  FILE     *fpin, *fpout;
  /* Local variables */
  double   prob, xstd, ystd;
  double   t;
  double   xmean, ymean, df, dl, du;
  double   clevel;

  Integer  exit_status = 0, nx, ny;
  NagError fail;

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);

  fprintf(fpout, "nag_2_sample_t_test (g07cac) Example Program Results\n");
  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n]");
  fscanf(fpin, "%ld %ld", &nx, &ny);
  fscanf(fpin, "%lf %lf %lf %lf", &xmean, &ymean, &xstd, &ystd);
  fscanf(fpin, "%lf", &clevel);

  /* nag_2_sample_t_test (g07cac).
   * Computes t-test statistic for a difference in means
   * between two Normal populations, confidence interval
   */
  nag_2_sample_t_test(Nag_TwoTail, Nag_PopVarEqual, nx, ny, xmean, ymean, xstd,
                      ystd, clevel, &t, &df, &prob, &dl, &du, &fail);

  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_2_sample_t_test (g07cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }
  fprintf(fpout, "\nAssuming population variances are equal.\n\n");
  fprintf(fpout, "t test statistic = %10.4f\n", t);
  fprintf(fpout, "Degrees of freedom = %8.1f\n", df);
  fprintf(fpout, "Significance level = %8.4f\n", prob);
  fprintf(fpout,
          "Lower confidence limit for difference in means = %10.4f\n", dl);
  fprintf(fpout,
          "Upper confidence limit for difference in means = %10.4f\n\n", du);

  /* nag_2_sample_t_test (g07cac), see above. */
  nag_2_sample_t_test(Nag_TwoTail, Nag_PopVarNotEqual, nx, ny, xmean, ymean,
                      xstd, ystd, clevel, &t, &df, &prob, &dl, &du,
                      &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_2_sample_t_test (g07cac).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  fprintf(fpout, "\nNo assumptions about population variances.\n\n");
  fprintf(fpout, "t test statistic = %10.4f\n", t);
  fprintf(fpout, "Degrees of freedom = %8.4f\n", df);
  fprintf(fpout, "Significance level = %8.4f\n", prob);
  fprintf(fpout, "Lower confidence limit for difference in means = %10.4f\n",
          dl);
  fprintf(fpout, "Upper confidence limit for difference in means = %10.4f\n",
          du);
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  return exit_status;
}