/* nag_zeros_real_poly (c02agc) Example Program.

 *

 * Copyright 1991 Numerical Algorithms Group.

 *

 * Mark 2, 1991.

 *

 * Mark 8 revised, 2004.

 */



#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);

  Vprintf("nag_zeros_real_poly (c02agc) Example Program Results\n");

  /* Skip heading in data file */

  Vscanf("%*[^\n]");

  Vscanf("%ld", &n);

  if (n>0)

    {

      scale  = Nag_TRUE;

      if ( !( a = NAG_ALLOC(n+1, double))  ||

           !( z = NAG_ALLOC(n, Complex)) )

        {

          Vprintf("Allocation failure\n");

          exit_status = -1;

          goto END;

        }

    }

  else

    {

      Vprintf("Invalid n.\n");

      exit_status = 1;

      return exit_status;

    }



  for (i=0; i<=n; i++)

    Vscanf("%lf", &a[i]);

  Vprintf("\nDegree of polynomial = %4ld\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)

    {

      Vprintf("Error from nag_zeros_real_poly (c02agc).\n%s\n", fail.message);

      exit_status = 1;

      goto END;

    }



  Vprintf("Roots of polynomial\n\n");

  nroot = 1;

  while(nroot<=n)

    {

      if (z[nroot-1].im==0.0)

        {

          Vprintf("z = %12.4e\n", z[nroot-1].re);

          nroot += 1;

        }

      else

        {

          Vprintf("z = %12.4e   +/- %14.4e\n", z[nroot-1].re,

                  fabs(z[nroot-1].im));

          nroot += 2;

        }

    }

 END:

  if (a) NAG_FREE(a);

  if (z) NAG_FREE(z);

  return exit_status;

}