Example #1
0
File: sub.c Project: argriffing/arb
static slong _fmpr_sub_special(fmpr_t z, const fmpr_t x, const fmpr_t y, slong prec, fmpr_rnd_t rnd)
{
    if (fmpr_is_zero(x))
    {
        return fmpr_neg_round(z, y, prec, rnd);
    }
    else if (fmpr_is_zero(y))
    {
        return fmpr_set_round(z, x, prec, rnd);
    }
    else if (fmpr_is_nan(x) || fmpr_is_nan(y)
        || (fmpr_is_pos_inf(x) && fmpr_is_pos_inf(y))
        || (fmpr_is_neg_inf(x) && fmpr_is_neg_inf(y)))
    {
        fmpr_nan(z);
        return FMPR_RESULT_EXACT;
    }
    else if (fmpr_is_special(x))
    {
        fmpr_set(z, x);
        return FMPR_RESULT_EXACT;
    }
    else
    {
        fmpr_neg(z, y);
        return FMPR_RESULT_EXACT;
    }
}
Example #2
0
int _fmprb_vec_rad_has_inf_nan(fmprb_srcptr vec, long len)
{
    long i;
    for (i = 0; i < len; i++)
        if (fmpr_is_nan(fmprb_radref(vec + i))
            || fmpr_is_inf(fmprb_radref(vec + i)))
            return 1;
    return 0;
}
Example #3
0
static void
_fmpr_div_special(fmpr_t z, const fmpr_t x, const fmpr_t y)
{
    if ((fmpr_is_zero(x) && !fmpr_is_zero(y) && !fmpr_is_nan(y)) ||
        (fmpr_is_inf(y) && !fmpr_is_special(x)))
    {
        fmpr_zero(z);
    }
    else if (fmpr_is_zero(y) || (fmpr_is_special(x) && fmpr_is_special(y)) ||
        fmpr_is_nan(x) || fmpr_is_nan(y))
    {
        fmpr_nan(z);
    }
    else if (fmpr_sgn(x) == fmpr_sgn(y))
        fmpr_pos_inf(z);
    else
        fmpr_neg_inf(z);
}
Example #4
0
int
fmpr_cmpabs(const fmpr_t x, const fmpr_t y)
{
    int res, xsign, ysign;
    fmpr_t t;

    if (fmpr_equal(x, y))
        return 0;

    if (fmpr_is_special(x) || fmpr_is_special(y))
    {
        if (fmpr_is_nan(x) || fmpr_is_nan(y))
            return 0;
        if (fmpr_is_zero(x)) return -1;
        if (fmpr_is_zero(y)) return 1;
        if (fmpr_is_inf(x)) return fmpr_is_inf(y) ? 0 : 1;
        if (fmpr_is_inf(y)) return -1;
        return -1;
    }

    /* Reduces to integer comparison if bottom exponents are the same */
    if (fmpz_equal(fmpr_expref(x), fmpr_expref(y)))
    {
        res = fmpz_cmpabs(fmpr_manref(x), fmpr_manref(y));
        if (res != 0)
            res = (res < 0) ? -1 : 1;
    }
    else
    {
        /* TODO: compare position of top exponents to avoid subtraction */
        xsign = fmpr_sgn(x);
        ysign = fmpr_sgn(y);

        fmpr_init(t);
        if (xsign == ysign)
            fmpr_sub(t, x, y, 2, FMPR_RND_DOWN);
        else
            fmpr_add(t, x, y, 2, FMPR_RND_DOWN);
        res = fmpr_sgn(t) * xsign;
        fmpr_clear(t);
    }

    return res;
}
Example #5
0
File: cmp.c Project: bluescarni/arb
int
fmpr_cmp(const fmpr_t x, const fmpr_t y)
{
    int res, xsign, ysign;
    fmpr_t t;

    if (fmpr_equal(x, y))
        return 0;

    if (fmpr_is_special(x) || fmpr_is_special(y))
    {
        if (fmpr_is_nan(x) || fmpr_is_nan(y))
            return 0;
        if (fmpr_is_zero(y)) return fmpr_sgn(x);
        if (fmpr_is_zero(x)) return -fmpr_sgn(y);
        if (fmpr_is_pos_inf(x)) return 1;
        if (fmpr_is_neg_inf(y)) return 1;
        return -1;
    }

    xsign = fmpr_sgn(x);
    ysign = fmpr_sgn(y);

    if (xsign != ysign)
        return (xsign < 0) ? -1 : 1;

    /* Reduces to integer comparison if bottom exponents are the same */
    if (fmpz_equal(fmpr_expref(x), fmpr_expref(y)))
        return fmpz_cmp(fmpr_manref(x), fmpr_manref(y)) < 0 ? -1 : 1;

    /* TODO: compare position of top exponents to avoid subtraction */

    fmpr_init(t);
    fmpr_sub(t, x, y, 2, FMPR_RND_DOWN);
    res = fmpr_sgn(t);
    fmpr_clear(t);

    return res;
}
Example #6
0
File: t-sub.c Project: isuruf/arb
int main()
{
    slong iter;
    flint_rand_t state;

    flint_printf("sub....");
    fflush(stdout);

    flint_randinit(state);

    /* test exact subtraction: (x - y) - z == (x - z) - y */
    for (iter = 0; iter < 100000; iter++)
    {
        slong bits, res1, res2, res3, res4;
        fmpr_t x, y, z, t, u;

        bits = 2 + n_randint(state, 200);

        fmpr_init(x);
        fmpr_init(y);
        fmpr_init(z);
        fmpr_init(t);
        fmpr_init(u);

        fmpr_randtest_special(x, state, bits, 10);
        fmpr_randtest_special(y, state, bits, 10);
        fmpr_randtest_special(z, state, bits, 10);
        fmpr_randtest_special(t, state, bits, 10);
        fmpr_randtest_special(u, state, bits, 10);

        res1 = fmpr_sub(t, x, y, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res2 = fmpr_sub(t, t, z, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res3 = fmpr_sub(u, x, z, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res4 = fmpr_sub(u, u, y, FMPR_PREC_EXACT, FMPR_RND_DOWN);

        if (!fmpr_equal(t, u) ||
            res1 != FMPR_RESULT_EXACT || res2 != FMPR_RESULT_EXACT ||
            res3 != FMPR_RESULT_EXACT || res4 != FMPR_RESULT_EXACT)
        {
            flint_printf("FAIL\n\n");
            flint_printf("bits = %wd\n", bits);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("t = "); fmpr_print(t); flint_printf("\n\n");
            flint_printf("u = "); fmpr_print(u); flint_printf("\n\n");
            abort();
        }

        fmpr_clear(x);
        fmpr_clear(y);
        fmpr_clear(z);
        fmpr_clear(t);
        fmpr_clear(u);
    }

    /* compare rounding with mpfr */
    for (iter = 0; iter < 100000; iter++)
    {
        slong bits, res;
        int mpfr_res;
        fmpr_t x, y, z, w;
        mpfr_t X, Y, Z;

        bits = 2 + n_randint(state, 200);

        fmpr_init(x);
        fmpr_init(y);
        fmpr_init(z);
        fmpr_init(w);

        mpfr_init2(X, bits + 100);
        mpfr_init2(Y, bits + 100);
        mpfr_init2(Z, bits);

        fmpr_randtest_special(x, state, bits + n_randint(state, 100), 10);
        fmpr_randtest_special(y, state, bits + n_randint(state, 100), 10);
        fmpr_randtest_special(z, state, bits, 10);

        fmpr_get_mpfr(X, x, MPFR_RNDN);
        fmpr_get_mpfr(Y, y, MPFR_RNDN);

        switch (n_randint(state, 4))
        {
            case 0:
                mpfr_res = mpfr_sub(Z, X, Y, MPFR_RNDZ);
                res = fmpr_sub(z, x, y, bits, FMPR_RND_DOWN);
                break;
            case 1:
                mpfr_res = mpfr_sub(Z, X, Y, MPFR_RNDA);
                res = fmpr_sub(z, x, y, bits, FMPR_RND_UP);
                break;
            case 2:
                mpfr_res = mpfr_sub(Z, X, Y, MPFR_RNDD);
                res = fmpr_sub(z, x, y, bits, FMPR_RND_FLOOR);
                break;
            default:
                mpfr_res = mpfr_sub(Z, X, Y, MPFR_RNDU);
                res = fmpr_sub(z, x, y, bits, FMPR_RND_CEIL);
                break;
        }

        fmpr_set_mpfr(w, Z);

        if (!fmpr_equal(z, w) || (res == FMPR_RESULT_EXACT) != (mpfr_res == 0)
            || !fmpr_check_ulp(z, res, bits))
        {
            flint_printf("FAIL\n\n");
            flint_printf("bits = %wd\n", bits);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("w = "); fmpr_print(w); flint_printf("\n\n");
            flint_printf("returned: %wd, %d\n", res, mpfr_res);
            abort();
        }

        /* check error bound */
        if (!fmpr_is_nan(z) && !fmpr_is_inf(z))
        {
            fmpr_t z_exact, error_bound, true_error;

            fmpr_init(z_exact);
            fmpr_init(error_bound);
            fmpr_init(true_error);

            fmpr_set_error_result(error_bound, z, res);
            fmpr_sub(z_exact, x, y, FMPR_PREC_EXACT, FMPR_RND_DOWN);

            fmpr_sub(true_error, z, z_exact, FMPR_PREC_EXACT, FMPR_RND_DOWN);
            fmpr_abs(true_error, true_error);

            if (fmpr_is_zero(error_bound) != fmpr_is_zero(true_error) ||
                fmpr_cmp(true_error, error_bound) > 0)
            {
                flint_printf("FAIL: error bound\n\n");
                flint_printf("bits = %wd\n", bits);
                flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
                flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
                flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
                flint_printf("z_exact = "); fmpr_print(z_exact); flint_printf("\n\n");
                flint_printf("true_error = "); fmpr_print(true_error); flint_printf("\n\n");
                flint_printf("error_bound = "); fmpr_print(error_bound); flint_printf("\n\n");
                abort();
            }

            fmpr_clear(z_exact);
            fmpr_clear(error_bound);
            fmpr_clear(true_error);
        }

        fmpr_clear(x);
        fmpr_clear(y);
        fmpr_clear(z);
        fmpr_clear(w);

        mpfr_clear(X);
        mpfr_clear(Y);
        mpfr_clear(Z);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
Example #7
0
int main()
{
    slong iter;
    flint_rand_t state;

    flint_printf("add....");
    fflush(stdout);

    flint_randinit(state);

    /* test exact addition: (x + y) + z == x + (y + z) */
    for (iter = 0; iter < 100000 * arb_test_multiplier(); iter++)
    {
        slong bits, res1, res2, res3, res4;
        fmpr_t x, y, z, t, u;

        bits = 2 + n_randint(state, 200);

        fmpr_init(x);
        fmpr_init(y);
        fmpr_init(z);
        fmpr_init(t);
        fmpr_init(u);

        fmpr_randtest_special(x, state, bits, 10);
        fmpr_randtest_special(y, state, bits, 10);
        fmpr_randtest_special(z, state, bits, 10);
        fmpr_randtest_special(t, state, bits, 10);
        fmpr_randtest_special(u, state, bits, 10);

        res1 = fmpr_add(t, x, y, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res2 = fmpr_add(t, t, z, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res3 = fmpr_add(u, y, z, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res4 = fmpr_add(u, x, u, FMPR_PREC_EXACT, FMPR_RND_DOWN);

        if (!fmpr_equal(t, u) ||
            res1 != FMPR_RESULT_EXACT || res2 != FMPR_RESULT_EXACT ||
            res3 != FMPR_RESULT_EXACT || res4 != FMPR_RESULT_EXACT)
        {
            flint_printf("FAIL\n\n");
            flint_printf("bits = %wd\n", bits);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("t = "); fmpr_print(t); flint_printf("\n\n");
            flint_printf("u = "); fmpr_print(u); flint_printf("\n\n");
            abort();
        }

        fmpr_clear(x);
        fmpr_clear(y);
        fmpr_clear(z);
        fmpr_clear(t);
        fmpr_clear(u);
    }

    /* compare with add_naive */
    for (iter = 0; iter < 1000000 * arb_test_multiplier(); iter++)
    {
        slong prec, ret1, ret2;
        fmpr_t x, y, z, w;
        fmpr_rnd_t rnd;

        fmpr_init(x);
        fmpr_init(y);
        fmpr_init(z);
        fmpr_init(w);

        fmpr_randtest_special(x, state, 1 + n_randint(state, 1000), 1 + n_randint(state, 200));
        fmpr_randtest_special(y, state, 1 + n_randint(state, 1000), 1 + n_randint(state, 200));
        fmpr_randtest_special(z, state, 1 + n_randint(state, 1000), 1 + n_randint(state, 200));

        prec = 2 + n_randint(state, 1000);
        if (n_randint(state, 10) == 0 &&
                fmpz_bits(fmpr_expref(x)) < 10 &&
                fmpz_bits(fmpr_expref(y)) < 10)
            prec = FMPR_PREC_EXACT;

        switch (n_randint(state, 4))
        {
            case 0: rnd = FMPR_RND_DOWN; break;
            case 1: rnd = FMPR_RND_UP; break;
            case 2: rnd = FMPR_RND_FLOOR; break;
            default: rnd = FMPR_RND_CEIL; break;
        }

        ret1 = fmpr_add(z, x, y, prec, rnd);
        ret2 = fmpr_add_naive(w, x, y, prec, rnd);

        if (!fmpr_equal(z, w) || ret1 != ret2 ||
            !fmpr_check_ulp(z, ret1, prec) || !fmpr_check_ulp(w, ret2, prec))
        {
            flint_printf("FAIL\n\n");
            flint_printf("iter %wd\n", iter);
            flint_printf("prec = %wd\n", prec);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("w = "); fmpr_print(w); flint_printf("\n\n");
            flint_printf("ret1 = %wd, ret2 = %wd\n", ret1, ret2);
            abort();
        }

        fmpr_clear(x);
        fmpr_clear(y);
        fmpr_clear(z);
        fmpr_clear(w);
    }

    /* compare rounding with mpfr */
    for (iter = 0; iter < 1000000 * arb_test_multiplier(); iter++)
    {
        slong bits, res;
        int mpfr_res;
        fmpr_t x, y, z, w;
        mpfr_t X, Y, Z;

        bits = 2 + n_randint(state, 500);

        fmpr_init(x);
        fmpr_init(y);
        fmpr_init(z);
        fmpr_init(w);

        mpfr_init2(X, bits + 500);
        mpfr_init2(Y, bits + 500);
        mpfr_init2(Z, bits);

        fmpr_randtest_special(x, state, bits + n_randint(state, 500), 10);
        fmpr_randtest_special(y, state, bits + n_randint(state, 500), 10);
        fmpr_randtest_special(z, state, bits, 10);

        fmpr_get_mpfr(X, x, MPFR_RNDN);
        fmpr_get_mpfr(Y, y, MPFR_RNDN);

        switch (n_randint(state, 4))
        {
            case 0:
                mpfr_res = mpfr_add(Z, X, Y, MPFR_RNDZ);
                res = fmpr_add(z, x, y, bits, FMPR_RND_DOWN);
                break;
            case 1:
                mpfr_res = mpfr_add(Z, X, Y, MPFR_RNDA);
                res = fmpr_add(z, x, y, bits, FMPR_RND_UP);
                break;
            case 2:
                mpfr_res = mpfr_add(Z, X, Y, MPFR_RNDD);
                res = fmpr_add(z, x, y, bits, FMPR_RND_FLOOR);
                break;
            default:
                mpfr_res = mpfr_add(Z, X, Y, MPFR_RNDU);
                res = fmpr_add(z, x, y, bits, FMPR_RND_CEIL);
                break;
        }

        fmpr_set_mpfr(w, Z);

        if (!fmpr_equal(z, w) || (res == FMPR_RESULT_EXACT) != (mpfr_res == 0)
            || !fmpr_check_ulp(z, res, bits))
        {
            flint_printf("FAIL\n\n");
            flint_printf("iter %wd\n", iter);
            flint_printf("bits = %wd\n", bits);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("w = "); fmpr_print(w); flint_printf("\n\n");
            flint_printf("returned: %wd, %d\n", res, mpfr_res);
            abort();
        }

        /* check error bound */
        if (!fmpr_is_nan(z) && !fmpr_is_inf(z))
        {
            fmpr_t z_exact, error_bound, true_error;

            fmpr_init(z_exact);
            fmpr_init(error_bound);
            fmpr_init(true_error);

            fmpr_set_error_result(error_bound, z, res);
            fmpr_add(z_exact, x, y, FMPR_PREC_EXACT, FMPR_RND_DOWN);

            fmpr_sub(true_error, z, z_exact, FMPR_PREC_EXACT, FMPR_RND_DOWN);
            fmpr_abs(true_error, true_error);

            if (fmpr_is_zero(error_bound) != fmpr_is_zero(true_error) ||
                fmpr_cmp(true_error, error_bound) > 0)
            {
                flint_printf("FAIL: error bound\n\n");
                flint_printf("bits = %wd\n", bits);
                flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
                flint_printf("y = "); fmpr_print(y); flint_printf("\n\n");
                flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
                flint_printf("z_exact = "); fmpr_print(z_exact); flint_printf("\n\n");
                flint_printf("true_error = "); fmpr_print(true_error); flint_printf("\n\n");
                flint_printf("error_bound = "); fmpr_print(error_bound); flint_printf("\n\n");
                abort();
            }

            fmpr_clear(z_exact);
            fmpr_clear(error_bound);
            fmpr_clear(true_error);
        }

        fmpr_clear(x);
        fmpr_clear(y);
        fmpr_clear(z);
        fmpr_clear(w);

        mpfr_clear(X);
        mpfr_clear(Y);
        mpfr_clear(Z);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
Example #8
0
File: gamma.c Project: jwbober/arb
static void
_fmprb_gamma(fmprb_t y, const fmprb_t x, long prec, int inverse)
{
    int reflect;
    long r, n, wp;
    fmprb_t t, u, v;

    if (fmprb_is_exact(x))
    {
        const fmpr_struct * mid = fmprb_midref(x);

        if (fmpr_is_special(mid))
        {
            if (!inverse && fmpr_is_pos_inf(mid))
            {
                fmprb_set(y, x);
            }
            else if (fmpr_is_nan(mid) || fmpr_is_neg_inf(mid) || !inverse)
            {
                fmpr_nan(fmprb_midref(y));
                fmpr_pos_inf(fmprb_radref(y));
            }
            else
            {
                fmprb_zero(y);
            }
            return;
        }
        else
        {
            const fmpz exp = *fmpr_expref(mid);
            const fmpz man = *fmpr_manref(mid);

            /* fast gamma(n), gamma(n/2) or gamma(n/4) */
            if (!COEFF_IS_MPZ(exp) && (exp >= -2) &&
                ((double) fmpz_bits(&man) + exp < prec))
            {
                fmpq_t a;
                fmpq_init(a);
                fmpr_get_fmpq(a, mid);
                fmprb_gamma_fmpq(y, a, prec + 2 * inverse);
                if (inverse)
                    fmprb_ui_div(y, 1, y, prec);
                fmpq_clear(a);
                return;
            }
        }
    }

    wp = prec + FLINT_BIT_COUNT(prec);

    gamma_stirling_choose_param_fmprb(&reflect, &r, &n, x, 1, 0, wp);

    fmprb_init(t);
    fmprb_init(u);
    fmprb_init(v);

    if (reflect)
    {
        /* gamma(x) = (rf(1-x, r) * pi) / (gamma(1-x+r) sin(pi x)) */
        fmprb_sub_ui(t, x, 1, wp);
        fmprb_neg(t, t);
        gamma_rising_fmprb_ui_bsplit(u, t, r, wp);
        fmprb_const_pi(v, wp);
        fmprb_mul(u, u, v, wp);
        fmprb_add_ui(t, t, r, wp);
        gamma_stirling_eval_fmprb(v, t, n, 0, wp);
        fmprb_exp(v, v, wp);
        fmprb_sin_pi(t, x, wp);
        fmprb_mul(v, v, t, wp);
    }
    else
    {
        /* gamma(x) = gamma(x+r) / rf(x,r) */
        fmprb_add_ui(t, x, r, wp);
        gamma_stirling_eval_fmprb(u, t, n, 0, wp);
        fmprb_exp(u, u, prec);
        gamma_rising_fmprb_ui_bsplit(v, x, r, wp);
    }

    if (inverse)
        fmprb_div(y, v, u, prec);
    else
        fmprb_div(y, u, v, prec);

    fmprb_clear(t);
    fmprb_clear(u);
    fmprb_clear(v);
}
Example #9
0
int main()
{
    slong iter;
    flint_rand_t state;

    flint_printf("abs_bound_lt_2exp_si....");
    fflush(stdout);

    flint_randinit(state);

    for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
    {
        fmpr_t x;
        fmpz_t b;
        slong c;

        fmpr_init(x);
        fmpz_init(b);

        fmpr_randtest_special(x, state, 2 + n_randint(state, 1000), 100);
        fmpr_abs_bound_lt_2exp_fmpz(b, x);
        c = fmpr_abs_bound_lt_2exp_si(x);

        if (c == -FMPR_PREC_EXACT)
        {
            if (!(fmpr_is_zero(x) || fmpz_cmp_si(b, -FMPR_PREC_EXACT) <= 0))
            {
                flint_printf("FAIL (small/zero)\n\n");
                abort();
            }
        }
        else if (c == FMPR_PREC_EXACT)
        {
            if (!(fmpr_is_inf(x) || fmpr_is_nan(x) ||
                fmpz_cmp_si(b, FMPR_PREC_EXACT) >= 0))
            {
                flint_printf("FAIL (large/inf/nan)\n\n");
                abort();
            }
        }
        else
        {
            if (fmpz_cmp_si(b, c) != 0)
            {
                flint_printf("FAIL (normal)\n\n");
                flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
                flint_printf("b = "); fmpz_print(b); flint_printf("\n\n");
                flint_printf("c = %wd\n\n", c);
                abort();
            }
        }

        fmpr_clear(x);
        fmpz_clear(b);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
Example #10
0
int
fmprb_contains(const fmprb_t x, const fmprb_t y)
{
    fmpr_t t;
    fmpr_t u;
    fmpr_struct tmp[4];
    int left_ok, right_ok;

    if (fmprb_is_exact(y))
        return fmprb_contains_fmpr(x, fmprb_midref(y));

    if (fmpr_is_nan(fmprb_midref(y)))
        return fmpr_is_nan(fmprb_midref(x));

    fmpr_init(t);
    fmpr_init(u);

    /* fast check */
    fmpr_sub(t, fmprb_midref(x), fmprb_radref(x), 30, FMPR_RND_CEIL);
    fmpr_sub(u, fmprb_midref(y), fmprb_radref(y), 30, FMPR_RND_FLOOR);
    left_ok = fmpr_cmp(t, u) <= 0;

    /* exact check */
    if (!left_ok)
    {
        fmpr_init(tmp + 0);
        fmpr_init(tmp + 1);
        fmpr_init(tmp + 2);
        fmpr_init(tmp + 3);

        fmpr_set(tmp + 0, fmprb_midref(x));
        fmpr_neg(tmp + 1, fmprb_radref(x));
        fmpr_neg(tmp + 2, fmprb_midref(y));
        fmpr_set(tmp + 3, fmprb_radref(y));

        fmpr_sum(t, tmp, 4, 30, FMPR_RND_DOWN);
        left_ok = fmpr_sgn(t) <= 0;

        fmpr_clear(tmp + 0);
        fmpr_clear(tmp + 1);
        fmpr_clear(tmp + 2);
        fmpr_clear(tmp + 3);
    }

    /* fast check */
    fmpr_add(t, fmprb_midref(x), fmprb_radref(x), 30, FMPR_RND_FLOOR);
    fmpr_add(u, fmprb_midref(y), fmprb_radref(y), 30, FMPR_RND_CEIL);
    right_ok = (fmpr_cmp(t, u) >= 0);

    /* exact check */
    if (!right_ok)
    {
        fmpr_init(tmp + 0);
        fmpr_init(tmp + 1);
        fmpr_init(tmp + 2);
        fmpr_init(tmp + 3);

        fmpr_set(tmp + 0, fmprb_midref(x));
        fmpr_set(tmp + 1, fmprb_radref(x));
        fmpr_neg(tmp + 2, fmprb_midref(y));
        fmpr_neg(tmp + 3, fmprb_radref(y));

        fmpr_sum(t, tmp, 4, 30, FMPR_RND_DOWN);
        right_ok = fmpr_sgn(t) >= 0;

        fmpr_clear(tmp + 0);
        fmpr_clear(tmp + 1);
        fmpr_clear(tmp + 2);
        fmpr_clear(tmp + 3);
    }

    fmpr_clear(t);
    fmpr_clear(u);

    return left_ok && right_ok;
}