/*===--------------------------------------------------------------------------
 *                   ROCm Device Libraries
 *
 * This file is distributed under the University of Illinois Open Source
 * License. See LICENSE.TXT for details.
 *===------------------------------------------------------------------------*/

#include "mathD.h"

#define DOUBLE_SPECIALIZATION
#include "ep.h"

extern CONSTATTR double MATH_PRIVATE(lnep)(double2 a, int ea);

CONSTATTR double
MATH_MANGLE(acosh)(double x)
{
    bool b = x >= 0x1.0p+512;
    double s = b ? 0x1.0p-512 : 1.0;
    double sx = x * s;
    double2 a = add(sx, root2(sub(sqr(sx), s*s)));
    double z = MATH_PRIVATE(lnep)(a, b ? 512 : 0);

    if (!FINITE_ONLY_OPT()) {
        z = x == PINF_F64 ? x : z;
        z = x < 1.0 ? QNAN_F64 : z;
    }

    return z;
}