diff options
Diffstat (limited to 'math/s_casinh.c')
| -rw-r--r-- | math/s_casinh.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/math/s_casinh.c b/math/s_casinh.c index 8c4aa19f63..acdf1a1e5a 100644 --- a/math/s_casinh.c +++ b/math/s_casinh.c @@ -62,20 +62,24 @@ __casinh (__complex__ double x) } else { + double rx, ix; __complex__ double y; - __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) + 1.0; - __imag__ y = 2.0 * __real__ x * __imag__ x; + /* Avoid cancellation by reducing to the first quadrant. */ + rx = fabs (__real__ x); + ix = fabs (__imag__ x); + + __real__ y = (rx - ix) * (rx + ix) + 1.0; + __imag__ y = 2.0 * rx * ix; y = __csqrt (y); - __real__ y += __real__ x; - __imag__ y += __imag__ x; + __real__ y += rx; + __imag__ y += ix; res = __clog (y); - /* Ensure zeros have correct sign and results are correct if - very close to branch cuts. */ + /* Give results the correct sign for the original argument. */ __real__ res = __copysign (__real__ res, __real__ x); __imag__ res = __copysign (__imag__ res, __imag__ x); } |