Haute précision

Quid de bibliothèques de haute précision ? Par exemple, GNU MPFR implémente les cinq modes d'arrondis d'IEEE754-2008.

/* linuxfr.c */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <mpfr.h>
void exemplifier(mpfr_t, mpfr_rnd_t, char **, size_t);
int main(int argc, char* argv[]) {
 mpfr_t x;
 mpfr_init2(x, 64);
 char *eleven[] = {"11.5", "-11.5"};
 char *twelve[] = {"12.5", "-12.5"};
 exemplifier(x, MPFR_RNDN, eleven, 2);
 exemplifier(x, MPFR_RNDN, twelve, 2);
 exemplifier(x, MPFR_RNDZ, eleven, 2);
 exemplifier(x, MPFR_RNDZ, twelve, 2);
 exemplifier(x, MPFR_RNDU, eleven, 2);
 exemplifier(x, MPFR_RNDU, twelve, 2);
 exemplifier(x, MPFR_RNDD, eleven, 2);
 exemplifier(x, MPFR_RNDD, twelve, 2);
 exemplifier(x, MPFR_RNDA, eleven, 2);
 exemplifier(x, MPFR_RNDA, twelve, 2);
 mpfr_clear(x);
 mpfr_free_cache();
 return 0;
}
void exemplifier(mpfr_t val, mpfr_rnd_t rnd, char **lit, size_t size) {
 size_t i = 0;
 fprintf(stdout, "\n");
 for(i = 0; i < size; ++i) {
 mpfr_set_str(val, lit[i], 10, rnd);
 mpfr_out_str(stdout, 10, 10, val, rnd);
 fprintf(stdout, "\t");
 }
 fprintf(stdout, "\n");
}

Disclaimer: n'ayant pas de grande aisance en C, je me fie au compilateur pour m'indiquer les éventuelles bourdes de ce que j'aurais commises.

gcc -lmpfr -lgmp -std=c11 -g -O3 -Wall -pedantic -Wextra -ggdb -fomit-frame-pointer -fstack-protector-all -ftrapv -pipe -flto linuxfr.c -o linuxfr

1.150000000e1 -1.150000000e1 
1.250000000e1 -1.250000000e1 
1.150000000e1 -1.150000000e1 
1.250000000e1 -1.250000000e1 
1.150000000e1 -1.150000000e1 
1.250000000e1 -1.250000000e1 
1.150000000e1 -1.150000000e1 
1.250000000e1 -1.250000000e1 
1.150000000e1 -1.150000000e1 
1.250000000e1 -1.250000000e1