diff options
Diffstat (limited to 'src/math/__expo2.c')
| -rw-r--r-- | src/math/__expo2.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/math/__expo2.c b/src/math/__expo2.c index 740ac680..248f052b 100644 --- a/src/math/__expo2.c +++ b/src/math/__expo2.c @@ -5,12 +5,13 @@ static const int k = 2043; static const double kln2 = 0x1.62066151add8bp+10; /* exp(x)/2 for x >= log(DBL_MAX), slightly better than 0.5*exp(x/2)*exp(x/2) */ -double __expo2(double x) +double __expo2(double x, double sign) { double scale; /* note that k is odd and scale*scale overflows */ INSERT_WORDS(scale, (uint32_t)(0x3ff + k/2) << 20, 0); /* exp(x - k ln2) * 2**(k-1) */ - return exp(x - kln2) * scale * scale; + /* in directed rounding correct sign before rounding or overflow is important */ + return exp(x - kln2) * (sign * scale) * scale; } |