diff options
Diffstat (limited to 'src/math/logl.c')
| -rw-r--r-- | src/math/logl.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/src/math/logl.c b/src/math/logl.c index ef2b5515..03c5188f 100644 --- a/src/math/logl.c +++ b/src/math/logl.c @@ -35,9 +35,9 @@ * * log(1+x) = x - 0.5 x**2 + x**3 P(x)/Q(x). * - * Otherwise, setting z = 2(x-1)/x+1), + * Otherwise, setting z = 2(x-1)/(x+1), * - * log(x) = z + z**3 P(z)/Q(z). + * log(x) = log(1+z/2) - log(1-z/2) = z + z**3 P(z)/Q(z). * * * ACCURACY: @@ -116,7 +116,7 @@ long double logl(long double x) return x; if (x <= 0.0) { if (x == 0.0) - return -1/(x+0); /* -inf with divbyzero */ + return -1/(x*x); /* -inf with divbyzero */ return 0/0.0f; /* nan with invalid */ } @@ -127,7 +127,7 @@ long double logl(long double x) x = frexpl(x, &e); /* logarithm using log(x) = z + z**3 P(z)/Q(z), - * where z = 2(x-1)/x+1) + * where z = 2(x-1)/(x+1) */ if (e > 2 || e < -2) { if (x < SQRTH) { /* 2(2x-1)/(2x+1) */ |