From d0419dbfbd19cb01398d43895a679c0bcb961070 Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Tue, 31 Jul 2012 14:21:19 +0000 Subject: Improve clog, clog10 handling of values with real or imaginary part slightly above 1 (bug 13629). --- math/s_clog10l.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'math/s_clog10l.c') diff --git a/math/s_clog10l.c b/math/s_clog10l.c index 2a380f6..d50f616 100644 --- a/math/s_clog10l.c +++ b/math/s_clog10l.c @@ -22,6 +22,13 @@ #include #include +/* To avoid spurious underflows, use this definition to treat IBM long + double as approximating an IEEE-style format. */ +#if LDBL_MANT_DIG == 106 +# undef LDBL_EPSILON +# define LDBL_EPSILON 0x1p-106L +#endif + /* log_10 (2). */ #define M_LOG10_2l 0.3010299956639811952137388947244930267682L @@ -75,6 +82,13 @@ __clog10l (__complex__ long double x) else __real__ result = __log1pl (absy2) * (M_LOG10El / 2.0L); } + else if (absx > 1.0L && absx < 2.0L && absy < 1.0L && scale == 0) + { + long double d2m1 = (absx - 1.0L) * (absx + 1.0L); + if (absy >= LDBL_EPSILON) + d2m1 += absy * absy; + __real__ result = __log1pl (d2m1) * (M_LOG10El / 2.0L); + } else { long double d = __ieee754_hypotl (absx, absy); -- cgit v1.1