volatile DOUBLE y = x;
volatile DOUBLE z = y;
- /* Round to the next integer (nearest or up or down, doesn't matter). */
if (z > L_(0.0))
{
- z += TWO_MANT_DIG;
- z -= TWO_MANT_DIG;
+ /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1. */
+ if (z < TWO_MANT_DIG)
+ {
+ /* Round to the next integer (nearest or up or down, doesn't matter). */
+ z += TWO_MANT_DIG;
+ z -= TWO_MANT_DIG;
+ /* Enforce rounding up. */
+ if (z < y)
+ z += L_(1.0);
+ }
}
else if (z < L_(0.0))
{
- z -= TWO_MANT_DIG;
- z += TWO_MANT_DIG;
+ /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1. */
+ if (z > - TWO_MANT_DIG)
+ {
+ /* Round to the next integer (nearest or up or down, doesn't matter). */
+ z -= TWO_MANT_DIG;
+ z += TWO_MANT_DIG;
+ /* Enforce rounding up. */
+ if (z < y)
+ z += L_(1.0);
+ }
}
- /* Enforce rounding up. */
- if (z < y)
- z += L_(1.0);
-
return z;
}