#include <stdio.h>
#include <stdarg.h>
// define MPFR_USE_VA_LIST to enable the use of mpfr_inits and mpfr_clears
#define MPFR_USE_VA_LIST
#include <mpfr.h>
#include <libinum.h>

int func(mpfr_t* out, mpfr_t in, void* extra_args);
int dfunc(mpfr_t* out, mpfr_t in, void* extra_args);

int main(int argc, const char* argv[]){
  int ret;
  mpfr_t init, prec, x;
  unsigned int maxiter;
  int extra_arg;

  mpfr_inits(init, prec, x, NULL);

  // start at 2
  mpfr_set_ui(init, 2, MPFR_RNDN);
  // precision
  mpfr_set_d(prec, 1.e-30, MPFR_RNDN);
  // maximum number of iterations before error
  maxiter=10000;
  // extra argument
  extra_arg=4;

  // compute root
  ret=root_newton_mpfr(&x, &func, &dfunc, init, prec, maxiter, &extra_arg);

  // return codes
  if(ret==LIBINUM_ERROR_MAXITER){
    printf("error: maximum number of iterations reached\n");
  }
  else if(ret==LIBINUM_ERROR_NAN){
    printf("error: infinity encountered\n");
  }
  else{
    mpfr_printf("% 14.7Re\n", x);
  }

  mpfr_clears(init, prec, x, NULL);

  return(0);
}

// x^2-1
int func(mpfr_t* out, mpfr_t in, void* extra_args){
  mpfr_pow_ui(*out, in, 2, MPFR_RNDN);
  mpfr_add_d(*out, *out, -1./ *((int*)extra_args), MPFR_RNDN);
  return(0);
}

// 2*x
int dfunc(mpfr_t* out, mpfr_t in, void* extra_args){
  mpfr_mul_ui(*out, in, 2, MPFR_RNDN);
  return(0);
}