diff options
Diffstat (limited to 'math/s_casinh.c')
| -rw-r--r-- | math/s_casinh.c | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/math/s_casinh.c b/math/s_casinh.c index acdf1a1e5a..b493982d88 100644 --- a/math/s_casinh.c +++ b/math/s_casinh.c @@ -20,7 +20,7 @@ #include <complex.h> #include <math.h> #include <math_private.h> - +#include <float.h> __complex__ double __casinh (__complex__ double x) @@ -69,15 +69,29 @@ __casinh (__complex__ double x) rx = fabs (__real__ x); ix = fabs (__imag__ x); - __real__ y = (rx - ix) * (rx + ix) + 1.0; - __imag__ y = 2.0 * rx * ix; + if (rx >= 1.0 / DBL_EPSILON || ix >= 1.0 / DBL_EPSILON) + { + /* For large x in the first quadrant, x + csqrt (1 + x * x) + is sufficiently close to 2 * x to make no significant + difference to the result; avoid possible overflow from + the squaring and addition. */ + __real__ y = rx; + __imag__ y = ix; + res = __clog (y); + __real__ res += M_LN2; + } + else + { + __real__ y = (rx - ix) * (rx + ix) + 1.0; + __imag__ y = 2.0 * rx * ix; - y = __csqrt (y); + y = __csqrt (y); - __real__ y += rx; - __imag__ y += ix; + __real__ y += rx; + __imag__ y += ix; - res = __clog (y); + res = __clog (y); + } /* Give results the correct sign for the original argument. */ __real__ res = __copysign (__real__ res, __real__ x); |