diff options
author | nsz <nsz@port70.net> | 2012-03-19 22:57:58 +0100 |
---|---|---|
committer | nsz <nsz@port70.net> | 2012-03-19 22:57:58 +0100 |
commit | 2786c7d21611b9fa3b2fe356542cf213e7dd0ba4 (patch) | |
tree | b3954e9cec7580f5dc851491d3b60d808aae4259 /src/math/logl.c | |
parent | 01fdfd491b5d83b72099fbae14c4a71ed8e0b945 (diff) | |
download | musl-2786c7d21611b9fa3b2fe356542cf213e7dd0ba4.tar.gz musl-2786c7d21611b9fa3b2fe356542cf213e7dd0ba4.tar.bz2 musl-2786c7d21611b9fa3b2fe356542cf213e7dd0ba4.tar.xz musl-2786c7d21611b9fa3b2fe356542cf213e7dd0ba4.zip |
use scalbn or *2.0 instead of ldexp, fix fmal
Some code assumed ldexp(x, 1) is faster than 2.0*x,
but ldexp is a wrapper around scalbn which uses
multiplications inside, so this optimization is
wrong.
This commit also fixes fmal which accidentally
used ldexp instead of ldexpl loosing precision.
There are various additional changes from the
work-in-progress const cleanups.
Diffstat (limited to 'src/math/logl.c')
-rw-r--r-- | src/math/logl.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/src/math/logl.c b/src/math/logl.c index ee7ca64a..ffd81038 100644 --- a/src/math/logl.c +++ b/src/math/logl.c @@ -119,8 +119,8 @@ long double logl(long double x) return x; if (x == INFINITY) return x; - if (x <= 0.0L) { - if (x == 0.0L) + if (x <= 0.0) { + if (x == 0.0) return -INFINITY; return NAN; } @@ -137,12 +137,12 @@ long double logl(long double x) if (e > 2 || e < -2) { if (x < SQRTH) { /* 2(2x-1)/(2x+1) */ e -= 1; - z = x - 0.5L; - y = 0.5L * z + 0.5L; + z = x - 0.5; + y = 0.5 * z + 0.5; } else { /* 2 (x-1)/(x+1) */ - z = x - 0.5L; - z -= 0.5L; - y = 0.5L * x + 0.5L; + z = x - 0.5; + z -= 0.5; + y = 0.5 * x + 0.5; } x = z / y; z = x*x; @@ -156,14 +156,14 @@ long double logl(long double x) /* logarithm using log(1+x) = x - .5x**2 + x**3 P(x)/Q(x) */ if (x < SQRTH) { e -= 1; - x = ldexpl(x, 1) - 1.0L; /* 2x - 1 */ + x = 2.0*x - 1.0; } else { - x = x - 1.0L; + x = x - 1.0; } z = x*x; y = x * (z * __polevll(x, P, 6) / __p1evll(x, Q, 6)); y = y + e * C2; - z = y - ldexpl(z, -1); /* y - 0.5 * z */ + z = y - 0.5*z; /* Note, the sum of above terms does not exceed x/4, * so it contributes at most about 1/4 lsb to the error. */ |