double
__ieee754_exp2 (double x)
{
static const double himark = (double) DBL_MAX_EXP;
static const double lomark = (double) (DBL_MIN_EXP - DBL_MANT_DIG - 1);
/* Check for usual case. */
if (__glibc_likely (isless (x, himark)))
{
/* Exceptional cases: */
if (__glibc_unlikely (!isgreaterequal (x, lomark)))
{
if (isinf (x))
/* e^-inf == 0, with no error. */
return 0;
else
/* Underflow */
return TWOM1000 * TWOM1000;
}
static const double THREEp42 = 13194139533312.0;
int tval, unsafe;
double rx, x22, result;
union ieee754_double ex2_u, scale_u;
if (fabs (x) < DBL_EPSILON / 4.0)
return 1.0 + x;
{
SET_RESTORE_ROUND_NOEX (FE_TONEAREST);
/* 1. Argument reduction.
Choose integers ex, -256 <= t < 256, and some real
-1/1024 <= x1 <= 1024 so that
x = ex + t/512 + x1.
First, calculate rx = ex + t/512. */
rx = x + THREEp42;
rx -= THREEp42;
x -= rx; /* Compute x=x1. */
/* Compute tval = (ex*512 + t)+256.
Now, t = (tval mod 512)-256 and ex=tval/512 [that's mod, NOT %;
and /-round-to-nearest not the usual c integer /]. */
tval = (int) (rx * 512.0 + 256.0);
/* 2. Adjust for accurate table entry.
Find e so that
x = ex + t/512 + e + x2
where -1e6 < e < 1e6, and
(double)(2^(t/512+e))
is accurate to one part in 2^-64. */
/* 'tval & 511' is the same as 'tval%512' except that it's always
positive.
Compute x = x2. */
x -= exp2_deltatable[tval & 511];
/* 3. Compute ex2 = 2^(t/512+e+ex). */
ex2_u.d = exp2_accuratetable[tval & 511];
tval >>= 9;
/* x2 is an integer multiple of 2^-54; avoid intermediate
underflow from the calculation of x22 * x. */
unsafe = abs (tval) >= -DBL_MIN_EXP - 56;
ex2_u.ieee.exponent += tval >> unsafe;
scale_u.d = 1.0;
scale_u.ieee.exponent += tval - (tval >> unsafe);
/* 4. Approximate 2^x2 - 1, using a fourth-degree polynomial,
with maximum error in [-2^-10-2^-30,2^-10+2^-30]
less than 10^-19. */
x22 = (((.0096181293647031180
* x + .055504110254308625)
* x + .240226506959100583)
* x + .69314718055994495) * ex2_u.d;
math_opt_barrier (x22);
}
/* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex). */
result = x22 * x + ex2_u.d;
if (!unsafe)
return result;
else
return result * scale_u.d;
}
else
/* Return x, if x is a NaN or Inf; or overflow, otherwise. */
return TWO1023 * x;
double
__ieee754_remainder (double x, double y)
{
double z, d, xx;
int4 kx, ky, n, nn, n1, m1, l;
mynumber u, t, w = { { 0, 0 } }, v = { { 0, 0 } }, ww = { { 0, 0 } }, r;
u.x = x;
t.x = y;
kx = u.i[HIGH_HALF] & 0x7fffffff; /* no sign for x*/
t.i[HIGH_HALF] &= 0x7fffffff; /*no sign for y */
ky = t.i[HIGH_HALF];
/*------ |x| < 2^1023 and 2^-970 < |y| < 2^1024 ------------------*/
if (kx < 0x7fe00000 && ky < 0x7ff00000 && ky >= 0x03500000)
{
SET_RESTORE_ROUND_NOEX (FE_TONEAREST);
if (kx + 0x00100000 < ky)
return x;
if ((kx - 0x01500000) < ky)
{
z = x / t.x;
v.i[HIGH_HALF] = t.i[HIGH_HALF];
d = (z + big.x) - big.x;
xx = (x - d * v.x) - d * (t.x - v.x);
if (d - z != 0.5 && d - z != -0.5)
return (xx != 0) ? xx : ((x > 0) ? ZERO.x : nZERO.x);
else
{
if (fabs (xx) > 0.5 * t.x)
return (z > d) ? xx - t.x : xx + t.x;
else
return xx;
}
} /* (kx<(ky+0x01500000)) */
else
{
r.x = 1.0 / t.x;
n = t.i[HIGH_HALF];
nn = (n & 0x7ff00000) + 0x01400000;
w.i[HIGH_HALF] = n;
ww.x = t.x - w.x;
l = (kx - nn) & 0xfff00000;
n1 = ww.i[HIGH_HALF];
m1 = r.i[HIGH_HALF];
while (l > 0)
{
r.i[HIGH_HALF] = m1 - l;
z = u.x * r.x;
w.i[HIGH_HALF] = n + l;
ww.i[HIGH_HALF] = (n1) ? n1 + l : n1;
d = (z + big.x) - big.x;
u.x = (u.x - d * w.x) - d * ww.x;
l = (u.i[HIGH_HALF] & 0x7ff00000) - nn;
}
r.i[HIGH_HALF] = m1;
w.i[HIGH_HALF] = n;
ww.i[HIGH_HALF] = n1;
z = u.x * r.x;
d = (z + big.x) - big.x;
u.x = (u.x - d * w.x) - d * ww.x;
if (fabs (u.x) < 0.5 * t.x)
return (u.x != 0) ? u.x : ((x > 0) ? ZERO.x : nZERO.x);
else
if (fabs (u.x) > 0.5 * t.x)
return (d > z) ? u.x + t.x : u.x - t.x;
else
{
z = u.x / t.x; d = (z + big.x) - big.x;
return ((u.x - d * w.x) - d * ww.x);
}
}
} /* (kx<0x7fe00000&&ky<0x7ff00000&&ky>=0x03500000) */
else
{
if (kx < 0x7fe00000 && ky < 0x7ff00000 && (ky > 0 || t.i[LOW_HALF] != 0))
{
y = fabs (y) * t128.x;
z = __ieee754_remainder (x, y) * t128.x;
z = __ieee754_remainder (z, y) * tm128.x;
return z;
}
else
{
if ((kx & 0x7ff00000) == 0x7fe00000 && ky < 0x7ff00000 &&
(ky > 0 || t.i[LOW_HALF] != 0))
{
y = fabs (y);
z = 2.0 * __ieee754_remainder (0.5 * x, y);
d = fabs (z);
if (d <= fabs (d - y))
return z;
else if (d == y)
return 0.0 * x;
else
return (z > 0) ? z - y : z + y;
}
else /* if x is too big */
{
if (ky == 0 && t.i[LOW_HALF] == 0) /* y = 0 */
return (x * y) / (x * y);
else if (kx >= 0x7ff00000 /* x not finite */
|| (ky > 0x7ff00000 /* y is NaN */
|| (ky == 0x7ff00000 && t.i[LOW_HALF] != 0)))
return (x * y) / (x * y);
else
return x;
}
}
}
}
