/* nag_lambertW (c05bac) Example Program.
 *
 * Copyright 2008, Numerical Algorithms Group.
 *
 * Mark 9, 2009.
 */

#include <stdio.h>
#include <math.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagc05.h>

int main(void)
{
  /* Scalars */
  double      w, x;
  Integer     branch;
  Integer     exit_status = 0;
  char        offset[10];
  Nag_Boolean offsetenum;
  NagError    fail;

  INIT_FAIL(fail);

  printf("nag_lambertW (c05bac) Example Program Results\n");
  /* Skip heading in data file*/
  scanf("%*[^\n] ");
  scanf("%ld%*[^\n] ", &branch);
  scanf("%s%*[^\n] ", offset);
  /*
   * nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  offsetenum = (Nag_Boolean) nag_enum_name_to_value(offset);
  printf("\n");
  printf("branch = %ld\n", branch);
  printf("offset = %s\n", offset);
  printf("\n      x           w(x)\n\n");
  while (scanf("%lf%*[^\n] ", &x) != EOF)
    {
      /*
       * nag_lambertW (c05bac)
       * Real values of Lambert's W function, W(x)
       */
      w = nag_lambertW(x, branch, offsetenum, &fail);
      if (fail.code == NE_NOERROR)
        {
          printf("%14.5e%14.5e\n", x, w);
        }
      else
        {
          printf("Error from nag_lambertW (c05bac).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }
    }

 END:
  return exit_status;
}