diff options
Diffstat (limited to 'sysdeps/generic/s_clog.c')
-rw-r--r-- | sysdeps/generic/s_clog.c | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/sysdeps/generic/s_clog.c b/sysdeps/generic/s_clog.c new file mode 100644 index 0000000000..f796024b47 --- /dev/null +++ b/sysdeps/generic/s_clog.c @@ -0,0 +1,65 @@ +/* Compute complex natural logarithm. + Copyright (C) 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <complex.h> +#include <math.h> + +#include "math_private.h" + + +__complex__ double +__clog (__complex__ double x) +{ + __complex__ double result; + int rcls = fpclassify (__real__ x); + int icls = fpclassify (__imag__ x); + + if (rcls == FP_ZERO && icls == FP_ZERO) + { + /* Real and imaginary part are 0.0. */ + __imag__ result = signbit (__real__ x) ? M_PI : 0.0; + __imag__ result = __copysign (__imag__ result, __imag__ x); + /* Yes, the following line raises an exception. */ + __real__ result = -1.0 / fabs (__real__ x); + } + else if (rcls != FP_NAN && icls != FP_NAN) + { + /* Neither real nor imaginary part is NaN. */ + __real__ result = __ieee754_log (__ieee754_hypot (__real__ x, + __imag__ x)); + __imag__ result = __ieee754_atan2 (__imag__ x, __real__ x); + } + else + { + __imag__ result = __nan (""); + if (rcls == FP_INFINITE || icls == FP_INFINITE) + /* Real or imaginary part is infinite. */ + __real__ result = HUGE_VAL; + else + __real__ result = __nan (""); + } + + return result; +} +weak_alias (__clog, clog) +#ifdef NO_LONG_DOUBLE +strong_alias (__clog, __clogl) +weak_alias (__clog, clogl) +#endif |