NAG Library Manual, Mark 28.5
Interfaces:  FL   CL   CPP   AD
```/* nag_specfun_hyperg_confl_real_scaled (s22bbc) 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 exit_status = 0;
Integer k, maxexponent, scm;
double ani, adr, bni, bdr, delta, frm, x;
/* Arrays */
double frmv[2];
Integer scmv[2];
/* Nag Types */
NagError fail;

maxexponent = X02BLC;
printf(
"nag_specfun_hyperg_confl_real_scaled (s22bbc) Example Program Results\n\n");

ani = -10.0;
bni = 30.0;
delta = 1.0E-4;
adr = delta;
bdr = -delta;
x = 25.0;

printf("%9s%10s%10s%12s%9s%12s\n", "a", "b", "x", "frm", "scm", "M(a,b,x)");
for (k = 0; k < 2; k++) {
INIT_FAIL(fail);
/* Compute the real confluent hypergeometric function M(a,b,x) in scaled
* form using nag_specfun_hyperg_confl_real_scaled (s22bbc).
*/
nag_specfun_hyperg_confl_real_scaled(ani, adr, bni, bdr, x, &frm, &scm,
&fail);
switch (fail.code) {
case NE_NOERROR:
case NW_UNDERFLOW_WARN:
case NW_SOME_PRECISION_LOSS: {
if (scm < maxexponent)
printf(" %9.4f %9.4f %9.4f %13.4e %5" NAG_IFMT " %13.4e\n", ani + adr,
bni + bdr, x, frm, scm, frm * pow(2.0, scm));
else
printf(" %9.4f %9.4f %9.4f %13.4e %5" NAG_IFMT " %17s\n", ani + adr,
bni + bdr, x, frm, scm, "Not Representable");
frmv[k] = frm;
scmv[k] = scm;
break;
}
default: {
/* Either the result has overflowed, no accuracy may be assumed,
* or an input error has been detected.
*/
printf(" %9.4f %9.4f %9.4f %17s\n", ani + adr, bni + bdr, x, "FAILED");
exit_status = 1;
goto END;
}
}
adr = -adr;
bdr = -bdr;
}

/* Calculate the product M1*M2 */
frm = frmv[0] * frmv[1];
scm = scmv[0] + scmv[1];
printf("\n");
if (scm < maxexponent)
printf("%-30s%12.4e%6" NAG_IFMT "%12.4e\n", "Solution product", frm, scm,
frm * pow(2.0, scm));
else
printf("%-30s%12.4e%6" NAG_IFMT "%17s\n", "Solution product", frm, scm,
"Not Representable");

/* Calculate the ratio M1/M2 */
if (frmv[1] != 0.0) {
frm = frmv[0] / frmv[1];
scm = scmv[0] - scmv[1];
printf("\n");
if (scm < maxexponent)
printf("%-30s%12.4e%6" NAG_IFMT "%12.4e\n", "Solution ratio", frm, scm,
frm * pow(2.0, scm));
else
printf("%-30s%12.4e%6" NAG_IFMT "%17s\n", "Solution ratio", frm, scm,
"Not Representable");
}

END:
return exit_status;
}
```