```/* nag_ddot (f16eac) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.2, 2017.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf16.h>

int main(void)
{
/* Scalars */
Integer exit_status = 0;
double alpha, beta, r;
Integer call, i, incx, incy, ix, iy, n;

/* Arrays */
double *x = 0, *y = 0;

/* Nag Types */
Nag_ConjType conj = Nag_NoConj;
NagError fail;

INIT_FAIL(fail);
printf("nag_ddot (f16eac) Example Program Results\n\n");

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

/* Accumulate two dot products, set beta=zero initially. */
beta = 0.0;
for (call = 1; call <= 2; call++) {
/* Read data for dot product. */
scanf("%" NAG_IFMT "%*[^\n] ", &n);
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &incx, &incy);
if (!(x = NAG_ALLOC(1 + (n - 1) * ABS(incx), double)) ||
!(y = NAG_ALLOC(1 + (n - 1) * ABS(incy), double)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
scanf("%lf%*[^\n] ", &alpha);

/* Read the vectors x and y and store forwards or backwards
* as determined by incx (resp. incy). */
for (i = 0, ix = (incx > 0 ? 0 : (1-n)*incx); i < n; i++, ix += incx)
scanf("%lf", &x[ix]);
scanf("%*[^\n] ");

for (i = 0, iy = (incy > 0 ? 0 : (1-n)*incy); i < n; i++, iy += incy)
scanf("%lf", &y[iy]);
scanf("%*[^\n] ");

/* nag_ddot computes r = beta*r + alpha*(x^T*y). */
nag_ddot(conj, n, alpha, x, incx, beta, y, incy, &r, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_ddot (f16eac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
/* Reset beta for accumulation and deallocate x, y. */
beta = 1.0;
NAG_FREE(x);
NAG_FREE(y);
}
printf("Accumulated dot product, r = %9.4f\n", r);
END:
NAG_FREE(x);
NAG_FREE(y);
return exit_status;
}
```