arb/fmpr/test/t-ulp.c

/*
    Copyright (C) 2014 Fredrik Johansson

    This file is part of Arb.

    Arb is free software: you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License (LGPL) as published
    by the Free Software Foundation; either version 2.1 of the License, or
    (at your option) any later version.  See <http://www.gnu.org/licenses/>.
*/

#include "fmpr.h"

int main()
{
    slong iter;
    flint_rand_t state;

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

    flint_randinit(state);

    for (iter = 0; iter < 10000 * arb_test_multiplier(); iter++)
    {
        fmpr_t x, ulp, a, b;
        slong prec;

        fmpr_init(x);
        fmpr_init(ulp);
        fmpr_init(a);
        fmpr_init(b);

        prec = 2 + n_randint(state, 1000);
        fmpr_randtest_not_zero(x, state, 1 + n_randint(state, 1000),
            1 + n_randint(state, 100));

        fmpr_ulp(ulp, x, prec);

        fmpr_abs(a, x);
        fmpr_mul_2exp_si(a, a, -prec);
        fmpr_abs(b, x);
        fmpr_mul_2exp_si(b, b, -prec+1);

        if (!((fmpr_cmp(a, ulp) < 0) && (fmpr_cmp(ulp, b) <= 0)))
        {
            flint_printf("FAIL!\n");
            flint_printf("prec = %wd\n", prec);
            flint_printf("x = "); fmpr_print(x); flint_printf("\n");
            flint_printf("ulp = "); fmpr_print(ulp); flint_printf("\n");
            flint_printf("a = "); fmpr_print(a); flint_printf("\n");
            flint_printf("b = "); fmpr_print(b); flint_printf("\n");
            flint_abort();
        }

        fmpr_clear(x);
        fmpr_clear(ulp);
        fmpr_clear(a);
        fmpr_clear(b);
    }

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