Module gmp_mpfr_sys::mpfr

source ·
Expand description

Function and type bindings for the MPFR library.

§Examples

use core::mem::MaybeUninit;
use gmp_mpfr_sys::mpfr;
let one_third = 1.0_f64 / 3.0;
unsafe {
    let mut f = {
        let mut f = MaybeUninit::uninit();
        mpfr::init2(f.as_mut_ptr(), 53);
        f.assume_init()
    };
    let dir = mpfr::set_d(&mut f, one_third, mpfr::rnd_t::RNDN);
    assert_eq!(dir, 0);
    let d = mpfr::get_d(&f, mpfr::rnd_t::RNDN);
    assert_eq!(d, one_third);
    mpfr::clear(&mut f);
}

The following example is a translation of the MPFR sample found on the MPFR website. The program computes a lower bound on 1 + 1/1! + 1/2! + … + 1/100! using 200-bit precision. The program outputs:

Sum is 2.7182818284590452353602874713526624977572470936999595749669131e0

use core::ffi::c_int;
use core::mem::MaybeUninit;
use gmp_mpfr_sys::mpfr;
use gmp_mpfr_sys::mpfr::rnd_t;
use libc::STDOUT_FILENO;

fn main() {
    unsafe {
        let mut t = {
            let mut t = MaybeUninit::uninit();
            mpfr::init2(t.as_mut_ptr(), 200);
            t.assume_init()
        };
        mpfr::set_d(&mut t, 1.0, rnd_t::RNDD);

        let mut s = {
            let mut s = MaybeUninit::uninit();
            mpfr::init2(s.as_mut_ptr(), 200);
            s.assume_init()
        };
        mpfr::set_d(&mut s, 1.0, rnd_t::RNDD);

        let mut u = {
            let mut u = MaybeUninit::uninit();
            mpfr::init2(u.as_mut_ptr(), 200);
            u.assume_init()
        };

        for i in 1..=100 {
            mpfr::mul_ui(&mut t, &t, i, rnd_t::RNDU);
            mpfr::set_d(&mut u, 1.0, rnd_t::RNDD);
            mpfr::div(&mut u, &u, &t, rnd_t::RNDD);
            mpfr::add(&mut s, &s, &u, rnd_t::RNDD);
        }

        let stdout = libc::fdopen(STDOUT_FILENO, b"w\0".as_ptr().cast());
        libc::fputs(b"Sum is \0".as_ptr().cast(), stdout);
        mpfr::out_str(stdout, 10, 0, &s, rnd_t::RNDD);
        libc::fputc(b'\n' as c_int, stdout);
        libc::fclose(stdout);

        mpfr::clear(&mut s);
        mpfr::clear(&mut t);
        mpfr::clear(&mut u);
        mpfr::free_cache();
    }
}

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Type Aliases§