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#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);
}
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