```/* nag_zeros_real_poly (c02agc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.1, 2017.
*
*/

#include <nag.h>
#include <stdio.h>
#include <math.h>
#include <nag_stdlib.h>
#include <nagc02.h>

int main(void)
{

Nag_Boolean scale;
Complex *z = 0;
Integer exit_status = 0, i, n, nroot;
NagError fail;
double *a = 0;

INIT_FAIL(fail);

printf("nag_zeros_real_poly (c02agc) Example Program Results\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "", &n);
if (n > 0) {
scale = Nag_TRUE;
if (!(a = NAG_ALLOC(n + 1, double)) || !(z = NAG_ALLOC(n, Complex)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
}
else {
printf("Invalid n.\n");
exit_status = 1;
return exit_status;
}

for (i = 0; i <= n; i++)
scanf("%lf", &a[i]);
printf("\nDegree of polynomial = %4" NAG_IFMT "\n\n", n);

/* nag_zeros_real_poly (c02agc).
* Zeros of a polynomial with real coefficients
*/
nag_zeros_real_poly(n, a, scale, z, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_zeros_real_poly (c02agc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

printf("Roots of polynomial\n\n");
nroot = 1;
while (nroot <= n) {
if (z[nroot - 1].im == 0.0) {
printf("z = %13.4e\n", z[nroot - 1].re);
nroot += 1;
}
else {
printf("z = %13.4e   +/- %14.4e\n", z[nroot - 1].re,
fabs(z[nroot - 1].im));
nroot += 2;
}
}
END:
NAG_FREE(a);
NAG_FREE(z);
return exit_status;
}
```