diff options
Diffstat (limited to 'math/s_casinhl.c')
| -rw-r--r-- | math/s_casinhl.c | 33 |
1 files changed, 27 insertions, 6 deletions
diff --git a/math/s_casinhl.c b/math/s_casinhl.c index 83f8d1885d..d7c74593e4 100644 --- a/math/s_casinhl.c +++ b/math/s_casinhl.c @@ -20,7 +20,14 @@ #include <complex.h> #include <math.h> #include <math_private.h> +#include <float.h> +/* To avoid spurious overflows, 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 __complex__ long double __casinhl (__complex__ long double x) @@ -69,15 +76,29 @@ __casinhl (__complex__ long double x) rx = fabsl (__real__ x); ix = fabsl (__imag__ x); - __real__ y = (rx - ix) * (rx + ix) + 1.0; - __imag__ y = 2.0 * rx * ix; + if (rx >= 1.0L / LDBL_EPSILON || ix >= 1.0L / LDBL_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 = __clogl (y); + __real__ res += M_LN2l; + } + else + { + __real__ y = (rx - ix) * (rx + ix) + 1.0; + __imag__ y = 2.0 * rx * ix; - y = __csqrtl (y); + y = __csqrtl (y); - __real__ y += rx; - __imag__ y += ix; + __real__ y += rx; + __imag__ y += ix; - res = __clogl (y); + res = __clogl (y); + } /* Give results the correct sign for the original argument. */ __real__ res = __copysignl (__real__ res, __real__ x); |