Exemplo n.º 1
0
void
fmprb_mul_main_naive(fmprb_t z, const fmprb_t x, const fmprb_t y, slong prec)
{
    if (fmpr_is_pos_inf(fmprb_radref(x)) || fmpr_is_pos_inf(fmprb_radref(y)))
    {
        fmpr_mul(fmprb_midref(z), fmprb_midref(x), fmprb_midref(y), prec, FMPR_RND_DOWN);
        fmpr_pos_inf(fmprb_radref(z));
    }
    else
    {
        fmpr_t t, u;
        slong r;

        fmpr_init(t);
        fmpr_init(u);

        /* (x+a)*(y+b) = x*y + x*b + y*a + a*b*/

        fmpr_mul(t, fmprb_midref(x), fmprb_radref(y), FMPRB_RAD_PREC, FMPR_RND_UP);
        fmpr_abs(t, t);

        fmpr_mul(u, fmprb_midref(y), fmprb_radref(x), FMPRB_RAD_PREC, FMPR_RND_UP);
        fmpr_abs(u, u);

        fmpr_add(t, t, u, FMPRB_RAD_PREC, FMPR_RND_UP);
        fmpr_addmul(t, fmprb_radref(x), fmprb_radref(y), FMPRB_RAD_PREC, FMPR_RND_UP);

        r = fmpr_mul(fmprb_midref(z), fmprb_midref(x), fmprb_midref(y), prec, FMPR_RND_DOWN);
        fmpr_add_error_result(fmprb_radref(z), t,
            fmprb_midref(z), r, FMPRB_RAD_PREC, FMPR_RND_UP);

        fmpr_clear(t);
        fmpr_clear(u);
    }
}
Exemplo n.º 2
0
void
fmpr_divappr_abs_ubound(fmpr_t z, const fmpr_t x, const fmpr_t y, slong prec)
{
    if (fmpr_is_special(x) || fmpr_is_special(y) || fmpz_is_pm1(fmpr_manref(y)))
    {
        fmpr_div(z, x, y, prec, FMPR_RND_UP);
        fmpr_abs(z, z);
    }
    else
    {
        fmpz_t t, u;
        slong xbits, ybits, tbits, ubits, shift;

        xbits = fmpz_bits(fmpr_manref(x));
        ybits = fmpz_bits(fmpr_manref(y));

        fmpz_init(t);
        fmpz_init(u);

        ubits = FLINT_MIN(ybits, prec);
        tbits = prec + ubits + 1;

        /* upper bound for |x|, shifted */
        if (xbits <= tbits)
        {
            fmpz_mul_2exp(t, fmpr_manref(x), tbits - xbits);
            fmpz_abs(t, t);
        }
        else if (fmpz_sgn(fmpr_manref(x)) > 0)
        {
            fmpz_cdiv_q_2exp(t, fmpr_manref(x), xbits - tbits);
        }
        else
        {
            fmpz_fdiv_q_2exp(t, fmpr_manref(x), xbits - tbits);
            fmpz_neg(t, t);
        }

        /* lower bound for |y|, shifted */
        if (ybits <= ubits)
            fmpz_mul_2exp(u, fmpr_manref(y), ubits - ybits);
        else
            fmpz_tdiv_q_2exp(u, fmpr_manref(y), ybits - ubits);
        fmpz_abs(u, u);

        fmpz_cdiv_q(fmpr_manref(z), t, u);

        shift = (ubits - ybits) - (tbits - xbits);
        fmpz_sub(fmpr_expref(z), fmpr_expref(x), fmpr_expref(y));
        if (shift >= 0)
            fmpz_add_ui(fmpr_expref(z), fmpr_expref(z), shift);
        else
            fmpz_sub_ui(fmpr_expref(z), fmpr_expref(z), -shift);

        _fmpr_normalise(fmpr_manref(z), fmpr_expref(z), prec, FMPR_RND_UP);

        fmpz_clear(t);
        fmpz_clear(u);
    }
}
Exemplo n.º 3
0
void
fmprb_mul_fmpr_naive(fmprb_t z, const fmprb_t x, const fmpr_t y, slong prec)
{
    /* (x+a) * y = x*y + y*a */
    if (fmpr_is_pos_inf(fmprb_radref(x)))
    {
        fmpr_mul(fmprb_midref(z), fmprb_midref(x), y, prec, FMPR_RND_DOWN);
        fmpr_pos_inf(fmprb_radref(z));
    }
    else if (fmpr_is_zero(fmprb_radref(x)))
    {
        slong r;

        r = fmpr_mul(fmprb_midref(z), fmprb_midref(x), y, prec, FMPR_RND_DOWN);
        fmpr_set_error_result(fmprb_radref(z), fmprb_midref(z), r);
    }
    else
    {
        slong r;

        fmpr_mul(fmprb_radref(z), fmprb_radref(x), y, FMPRB_RAD_PREC, FMPR_RND_UP);
        fmpr_abs(fmprb_radref(z), fmprb_radref(z));

        r = fmpr_mul(fmprb_midref(z), fmprb_midref(x), y, prec, FMPR_RND_DOWN);
        fmpr_add_error_result(fmprb_radref(z), fmprb_radref(z),
            fmprb_midref(z), r, FMPRB_RAD_PREC, FMPR_RND_UP);
    }
}
Exemplo n.º 4
0
Arquivo: t-sub.c Projeto: 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;
}
Exemplo n.º 5
0
void _fmpr_fmpz_vec_max_norm(fmpr_t norm, const fmpz * vec, long len, long prec)
{
    fmpr_set_fmpz(norm, vec + _fmpz_vec_height_index(vec, len));
    fmpr_set_round(norm, norm, prec, FMPR_RND_UP);
    fmpr_abs(norm, norm);
}
Exemplo n.º 6
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;
}
Exemplo n.º 7
0
int main()
{
    slong iter;
    flint_rand_t state;

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

    flint_randinit(state);

    for (iter = 0; iter < 1000000 * arb_test_multiplier(); iter++)
    {
        slong i, len, prec, bits, expbits, res1, res2;
        fmpr_t s1, s2, s3, err, err_bound;
        fmpr_struct terms[20];
        fmpr_rnd_t rnd;

        len = n_randint(state, 20);
        bits = 2 + n_randint(state, 1000);
        prec = 2 + n_randint(state, 1000);
        expbits = n_randint(state, 14);

        fmpr_init(s1);
        fmpr_init(s2);
        fmpr_init(s3);
        fmpr_init(err);
        fmpr_init(err_bound);
        for (i = 0; i < len; i++)
        {
            fmpr_init(terms + i);
            fmpr_randtest_special(terms + i, state, bits, expbits);
        }

        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;
        }

        res1 = fmpr_sum(s1, terms, len, prec, rnd);

        fmpr_zero(s2);
        for (i = 0; i < len; i++)
            fmpr_add(s2, s2, terms + i, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        res2 = fmpr_set_round(s3, s2, prec, rnd);

        if (!fmpr_equal(s1, s3) || res1 != res2 ||
            !fmpr_check_ulp(s1, res1, prec) || !fmpr_check_ulp(s3, res2, prec))
        {
            flint_printf("FAIL (%wd)\n\n", iter);
            flint_printf("prec = %wd\n\n", prec);
            for (i = 0; i < len; i++)
            {
                flint_printf("terms[%wd] = ", i); fmpr_print(terms + i); flint_printf("\n\n");
            }
            flint_printf("s1 = "); fmpr_print(s1); flint_printf("\n\n");
            flint_printf("s2 = "); fmpr_print(s2); flint_printf("\n\n");
            flint_printf("s3 = "); fmpr_print(s3); flint_printf("\n\n");
            flint_printf("res1 = %wd, res2 = %wd\n\n", res1, res2);
            abort();
        }

        fmpr_sub(err, s1, s2, FMPR_PREC_EXACT, FMPR_RND_DOWN);
        fmpr_abs(err, err);
        fmpr_set_error_result(err_bound, s1, res1);

        if (fmpr_cmp(err, err_bound) > 0)
        {
            flint_printf("FAIL (error bound)!\n");
            flint_printf("prec = %wd\n\n", prec);
            for (i = 0; i < len; i++)
            {
                flint_printf("terms[%wd] = ", i); fmpr_print(terms + i); flint_printf("\n\n");
            }
            flint_printf("s1 = "); fmpr_print(s1); flint_printf("\n\n");
            flint_printf("s2 = "); fmpr_print(s2); flint_printf("\n\n");
            flint_printf("s3 = "); fmpr_print(s3); flint_printf("\n\n");
            flint_printf("error: "); fmpr_print(err); flint_printf("\n\n");
            flint_printf("error bound: "); fmpr_print(err_bound); flint_printf("\n\n");
            flint_printf("res1 = %wd, res2 = %wd\n\n", res1, res2);
            abort();
        }

        fmpr_clear(s1);
        fmpr_clear(s2);
        fmpr_clear(s3);
        fmpr_clear(err);
        fmpr_clear(err_bound);
        for (i = 0; i < len; i++)
            fmpr_clear(terms + i);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}
Exemplo n.º 8
0
int main()
{
    slong iter;
    flint_rand_t state;

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

    flint_randinit(state);

    for (iter = 0; iter < 100000 * arb_test_multiplier(); iter++)
    {
        slong bits;
        ulong k;
        fmpr_t x, z, w;
        mpfr_t X, Z;

        bits = 2 + n_randint(state, 200);
        k = 1 + n_randint(state, 20);

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

        mpfr_init2(X, k * (bits + 100));
        mpfr_init2(Z, bits);

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

        /* occasionally produce perfect powers */
        if (n_randint(state, 4) == 0)
            fmpr_mul(x, x, x, k * bits, FMPR_RND_DOWN);

        fmpr_get_mpfr(X, x, MPFR_RNDN);

        switch (n_randint(state, 4))
        {
            case 0:
                mpfr_root(Z, X, k, MPFR_RNDZ);
                fmpr_root(z, x, k, bits, FMPR_RND_DOWN);
                break;
            case 1:
                mpfr_root(Z, X, k, MPFR_RNDA);
                fmpr_root(z, x, k, bits, FMPR_RND_UP);
                break;
            case 2:
                mpfr_root(Z, X, k, MPFR_RNDD);
                fmpr_root(z, x, k, bits, FMPR_RND_FLOOR);
                break;
            case 3:
                mpfr_root(Z, X, k, MPFR_RNDU);
                fmpr_root(z, x, k, bits, FMPR_RND_CEIL);
                break;
        }

        fmpr_set_mpfr(w, Z);

        if (!fmpr_equal(z, w))
        {
            flint_printf("FAIL\n\n");
            flint_printf("bits = %wd, k = %wu\n", bits, k);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n\n");
            flint_printf("z = "); fmpr_print(z); flint_printf("\n\n");
            flint_printf("w = "); fmpr_print(w); flint_printf("\n\n");
            abort();
        }

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

        mpfr_clear(X);
        mpfr_clear(Z);
    }

    flint_randclear(state);
    flint_cleanup();
    flint_printf("PASS\n");
    return EXIT_SUCCESS;
}