/* nag_univar_ttest_2normal (g07cac) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 *
 */

#include <nag.h>
#include <stdio.h>

int main(void) {
  /* 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);

  printf("nag_univar_ttest_2normal (g07cac) Example Program Results\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT " %" NAG_IFMT "", &nx, &ny);
  scanf("%lf %lf %lf %lf", &xmean, &ymean, &xstd, &ystd);
  scanf("%lf", &clevel);

  /* nag_univar_ttest_2normal (g07cac).
   * Computes t-test statistic for a difference in means
   * between two Normal populations, confidence interval
   */
  nag_univar_ttest_2normal(Nag_TwoTail, Nag_PopVarEqual, nx, ny, xmean, ymean,
                           xstd, ystd, clevel, &t, &df, &prob, &dl, &du, &fail);

  if (fail.code != NE_NOERROR) {
    printf("Error from nag_univar_ttest_2normal (g07cac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }
  printf("\nAssuming population variances are equal.\n\n");
  printf("t test statistic = %10.4f\n", t);
  printf("Degrees of freedom = %8.1f\n", df);
  printf("Significance level = %8.4f\n", prob);
  printf("Lower confidence limit for difference in means = %10.4f\n", dl);
  printf("Upper confidence limit for difference in means = %10.4f\n\n", du);

  /* nag_univar_ttest_2normal (g07cac), see above. */
  nag_univar_ttest_2normal(Nag_TwoTail, Nag_PopVarNotEqual, nx, ny, xmean,
                           ymean, xstd, ystd, clevel, &t, &df, &prob, &dl, &du,
                           &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_univar_ttest_2normal (g07cac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

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