NAG Library Manual, Mark 28.5
```/* nag_stat_prob_bivariate_students_t (g01hcc) Example Program.
*
* Copyright 2022 Numerical Algorithms Group.
*
* Mark 28.5, 2022.
*/
#include <math.h>
#include <nag.h>
#include <stdio.h>
#include <string.h>

int main(void) {
/* Scalars */
Integer df, exit_status = 0, ierr;
double prob, rho;
/* Arrays */
char nag_enum_arg[14];
double a[2], b[2];
/* NAG types */
Nag_TailProbability tail;
NagError fail;

printf("%s\n\n",
"nag_stat_prob_bivariate_students_t (g01hcc) Example Program Results");

/* Skip heading in data file */
scanf("%*[^\n]");

printf("%-8s%2s%-8s%2s%-8s%2s%-8s%2s%-4s%2s%-8s%2s%-14s%2s%-8s\n\n", "a1",
" ", "b1", " ", "a2", " ", "b2", " ", "df", " ", "rho", " ", "Tail",
" ", "p");

while (1) {
ierr = scanf("%13s", nag_enum_arg);
if (ierr == EOF || ierr < 1) {
break;
}

/* Initialize limits */
a[0] = a[1] = b[0] = b[1] = 0.0;

/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
tail = (Nag_TailProbability)nag_enum_name_to_value(nag_enum_arg);

switch (tail) {
case Nag_LowerTail:
scanf("%" NAG_IFMT "%lf%lf%lf", &df, &rho, b, b + 1);
break;
case Nag_Central:
scanf("%" NAG_IFMT "%lf%lf%lf%lf%lf", &df, &rho, a, b, a + 1, b + 1);
break;
case Nag_UpperTail:
scanf("%" NAG_IFMT "%lf%lf%lf", &df, &rho, a, a + 1);
break;
default:
printf(" %s\n", "Invalid tail specification in data file");
exit_status = -1;
goto END;
}
scanf("%*[^\n]");

/* Calculate probability for the bivariate Student's t-distribution */
INIT_FAIL(fail);
/* nag_stat_prob_bivariate_students_t (g01hcc) */
prob = nag_stat_prob_bivariate_students_t(tail, a, b, df, rho, &fail);

/* Display results */
switch (tail) {
case Nag_LowerTail:
printf("%-8s%2s%-8g%2s%-8s%2s%-8g", "-Inf", " ", b[0], " ", "-Inf", " ",
b[1]);
break;
case Nag_Central:
printf("%-8g%2s%-8g%2s%-8g%2s%-8g", a[0], " ", b[0], " ", a[1], " ",
b[1]);
break;
case Nag_UpperTail:
printf("%-8g%2s%-8s%2s%-8g%2s%-8s", a[0], " ", "Inf", " ", a[1], " ",
"Inf");
break;
default: {
printf("Invalid tail specification.\n");
exit_status = -1;
goto END;
}
}

printf("%2s%-4" NAG_IFMT "%2s%-8g%2s%-14s%2s%-8.4f\n", " ", df, " ", rho,
" ", nag_enum_arg, " ", prob);
}

END:
return exit_status;
}
```