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Diffstat (limited to 'lib/msun/src/s_cexp.c')
-rw-r--r-- | lib/msun/src/s_cexp.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/lib/msun/src/s_cexp.c b/lib/msun/src/s_cexp.c new file mode 100644 index 0000000..abe178f --- /dev/null +++ b/lib/msun/src/s_cexp.c @@ -0,0 +1,89 @@ +/*- + * Copyright (c) 2011 David Schultz <das@FreeBSD.ORG> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <complex.h> +#include <math.h> + +#include "math_private.h" + +static const uint32_t +exp_ovfl = 0x40862e42, /* high bits of MAX_EXP * ln2 ~= 710 */ +cexp_ovfl = 0x4096b8e4; /* (MAX_EXP - MIN_DENORM_EXP) * ln2 */ + +double complex +cexp(double complex z) +{ + double x, y, exp_x; + uint32_t hx, hy, lx, ly; + + x = creal(z); + y = cimag(z); + + EXTRACT_WORDS(hy, ly, y); + hy &= 0x7fffffff; + + /* cexp(x + I 0) = exp(x) + I 0 */ + if ((hy | ly) == 0) + return (cpack(exp(x), y)); + EXTRACT_WORDS(hx, lx, x); + /* cexp(0 + I y) = cos(y) + I sin(y) */ + if (((hx & 0x7fffffff) | lx) == 0) + return (cpack(cos(y), sin(y))); + + if (hy >= 0x7ff00000) { + if (lx != 0 || (hx & 0x7fffffff) != 0x7ff00000) { + /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */ + return (cpack(y - y, y - y)); + } else if (hx & 0x80000000) { + /* cexp(-Inf +- I Inf|NaN) = 0 + I 0 */ + return (cpack(0.0, 0.0)); + } else { + /* cexp(+Inf +- I Inf|NaN) = Inf + I NaN */ + return (cpack(x, y - y)); + } + } + + if (hx >= exp_ovfl && hx <= cexp_ovfl) { + /* + * x is between 709.7 and 1454.3, so we must scale to avoid + * overflow in exp(x). + */ + return (__ldexp_cexp(z, 0)); + } else { + /* + * Cases covered here: + * - x < exp_ovfl and exp(x) won't overflow (common case) + * - x > cexp_ovfl, so exp(x) * s overflows for all s > 0 + * - x = +-Inf (generated by exp()) + * - x = NaN (spurious inexact exception from y) + */ + exp_x = exp(x); + return (cpack(exp_x * cos(y), exp_x * sin(y))); + } +} |