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| author | Joseph Myers <joseph@codesourcery.com> | 2012-07-05 11:02:13 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2012-07-05 11:02:13 +0000 |
| commit | cdfe2c5eb3703ed964cbfdb6906b21ace2956385 (patch) | |
| tree | c9e8f3452c8450524666f1287f5d8e0fc72a2875 /math/s_csqrtl.c | |
| parent | 704bc4594dc1fad46831823627749fa10924b41d (diff) | |
| download | glibc-cdfe2c5eb3703ed964cbfdb6906b21ace2956385.tar.gz glibc-cdfe2c5eb3703ed964cbfdb6906b21ace2956385.tar.xz glibc-cdfe2c5eb3703ed964cbfdb6906b21ace2956385.zip | |
Fix csqrt underflow (bugs 14157, 14331).
Diffstat (limited to 'math/s_csqrtl.c')
| -rw-r--r-- | math/s_csqrtl.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/math/s_csqrtl.c b/math/s_csqrtl.c index 64332f67b2..579d9768c2 100644 --- a/math/s_csqrtl.c +++ b/math/s_csqrtl.c @@ -75,7 +75,11 @@ __csqrtl (__complex__ long double x) } else if (__builtin_expect (rcls == FP_ZERO, 0)) { - long double r = __ieee754_sqrtl (0.5 * fabsl (__imag__ x)); + long double r; + if (fabsl (__imag__ x) >= 2.0L * LDBL_MIN) + r = __ieee754_sqrtl (0.5L * fabsl (__imag__ x)); + else + r = 0.5L * __ieee754_sqrtl (2.0L * fabsl (__imag__ x)); __real__ res = r; __imag__ res = __copysignl (r, __imag__ x); @@ -85,13 +89,21 @@ __csqrtl (__complex__ long double x) long double d, r, s; int scale = 0; - if (fabsl (__real__ x) > LDBL_MAX / 2.0L - || fabsl (__imag__ x) > LDBL_MAX / 2.0L) + if (fabsl (__real__ x) > LDBL_MAX / 4.0L) { scale = 1; __real__ x = __scalbnl (__real__ x, -2 * scale); __imag__ x = __scalbnl (__imag__ x, -2 * scale); } + else if (fabsl (__imag__ x) > LDBL_MAX / 4.0L) + { + scale = 1; + if (fabsl (__real__ x) >= 4.0L * LDBL_MIN) + __real__ x = __scalbnl (__real__ x, -2 * scale); + else + __real__ x = 0.0L; + __imag__ x = __scalbnl (__imag__ x, -2 * scale); + } else if (fabsl (__real__ x) < LDBL_MIN && fabsl (__imag__ x) < LDBL_MIN) { @@ -105,13 +117,13 @@ __csqrtl (__complex__ long double x) to avoid cancellation error in d +/- Re x. */ if (__real__ x > 0) { - r = __ieee754_sqrtl (0.5L * d + 0.5L * __real__ x); - s = (0.5L * __imag__ x) / r; + r = __ieee754_sqrtl (0.5L * (d + __real__ x)); + s = 0.5L * (__imag__ x / r); } else { - s = __ieee754_sqrtl (0.5L * d - 0.5L * __real__ x); - r = fabsl ((0.5L * __imag__ x) / s); + s = __ieee754_sqrtl (0.5L * (d - __real__ x)); + r = fabsl (0.5L * (__imag__ x / s)); } if (scale) |