/*
    Copyright (C) 2014 Fredrik Johansson

    This file is part of FLINT.

    FLINT 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 3 of the License, or
    (at your option) any later version.  See <https://www.gnu.org/licenses/>.
*/

#include "test_helpers.h"
#include "double_extras.h"
#include "mpfr.h"
#include "mag.h"

/* Defined in t-d_log_lower_bound.c, t-d_log_upper_bound.c, t-set_d_2exp_fmpz.c
 * and t-set_d.c */
#ifndef d_randtest2
#define d_randtest2 d_randtest2
/* XXX: d_randtest is not good enough */

#define EXP_MINUS_32 2.3283064365386962891e-10
#define EXP_MINUS_64 5.42101086242752217e-20

double
d_randtest2(flint_rand_t state)
{
    ulong m1, m2;
    double t;

    if (FLINT_BITS == 64)
    {
        m1 = n_randtest(state) | (UWORD(1) << (FLINT_BITS - 1));

        t = ((double) m1) * EXP_MINUS_64;
    }
    else
    {
        m1 = n_randtest(state) | (UWORD(1) << (FLINT_BITS - 1));
        m2 = n_randtest(state);

        t = ((double) m1) * EXP_MINUS_32 +
            ((double) m2) * EXP_MINUS_64;
    }

    return t;
}
#endif

TEST_FUNCTION_START(mag_d_log_upper_bound, state)
{
    slong iter;

    for (iter = 0; iter < 100000 * 0.1 * flint_test_multiplier(); iter++)
    {
        mpfr_t t;
        double x, y, z;

        mpfr_init2(t, 53);

        x = d_randtest2(state);
        x = ldexp(x, 100 - n_randint(state, 200));

        switch (n_randint(state, 10))
        {
            case 0:
                x = 1.0 + x;
                break;
            case 1:
                x = 1.0 - x;
                break;
            case 2:
                x = D_INF;
                break;
            case 3:
                x = 0.0;
                break;
            case 4:
                x = D_NAN;
                break;
            default:
                break;
        }

        y = mag_d_log_upper_bound(x);

        mpfr_set_d(t, x, MPFR_RNDD);
        mpfr_log(t, t, MPFR_RNDU);
        z = mpfr_get_d(t, MPFR_RNDD);

        if (y < z || fabs(y-z) > 0.000001 * fabs(z))
        {
            flint_printf("FAIL\n");
            flint_printf("x = %.20g\n", x);
            flint_printf("y = %.20g\n", y);
            flint_printf("z = %.20g\n", z);
            flint_abort();
        }

        mpfr_clear(t);
    }

    TEST_FUNCTION_END(state);
}
