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author | Ulrich Drepper <drepper@redhat.com> | 1998-02-13 17:54:15 +0000 |
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committer | Ulrich Drepper <drepper@redhat.com> | 1998-02-13 17:54:15 +0000 |
commit | dc30f461575342ffeb6c0f2d5931493c1c3a91c0 (patch) | |
tree | 99243511beca706f0743fe2316854c5a30709f17 /sysdeps/libm-ieee754/s_exp2.c | |
parent | e15867921d8f3b75deb0d91628cf9a323709ea9f (diff) | |
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Update.
1998-02-13 17:39 Ulrich Drepper <drepper@cygnus.com>
* elf/Makefile: Don't use --version-script parameter to link ld.so
unconditionally.
1998-01-02 04:19 Geoff Keating <geoffk@ozemail.com.au>
* math/Makefile: Add t_exp.
* math/libm-test.c: Tighten accuracy bounds for exp(), correct
constants.
* math/test-reduce.c: Remove temporarily, it seems to be broken.
* sysdeps/libm-ieee754/e_exp.c: Use accurate table method.
* sysdeps/libm-ieee754/e_expf.c: Use table & double precision for
better accuracy.
* sysdeps/libm-ieee754/s_exp2.c: Use better polynomial; correct
algorithm for very large/very small arguments.
* sysdeps/libm-ieee754/s_exp2f.c: Use slightly better polynomial;
correct algorithm for very large/very small arguments; adjust for
new table.
* sysdeps/libm-ieee754/t_exp.c: New file.
* sysdeps/libm-ieee754/t_exp2f.h: Use table with smaller deltas.
* sysdeps/unix/sysv/linux/powerpc/dl-sysdep.c: Put 'strange test'
back, with comment that explains what breaks when you remove it :-(.
* localedata/xfrm-test.c: Avoid integer overflow.
* stdlib/strfmon.c: char is unsigned, sometimes.
*sysdeps/powerpc
* sysdeps/powerpc/Makefile: Remove quad float support.
* sysdeps/powerpc/q_*.c: Remove, they will become an add-on.
* sysdeps/powerpc/quad_float.h: Likewise.
* sysdeps/powerpc/test-arith.c: Likewise.
* sysdeps/powerpc/test-arithf.c: Likewise.
* sysdeps/generic/s_exp2.c: Remove, we have this implemented now.
* sysdeps/generic/s_exp2f.c: Likewise.
* sysdeps/powerpc/bits/mathinline.h: Use underscores around __asm__,
don't try anything if _SOFT_FLOAT.
1997-12-31 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* locale/C-ctype.c (_nl_C_LC_CTYPE_class32): Undo last change.
* locale/programs/ld-ctype.c (CHAR_CLASS32_TRANS): Likewise.
* wctype/wctype.c: Likewise.
* wctype/wctype.h (_ISwxxx): Renamed from _ISxxx, all uses
changed. They are incompatible with the _ISxxx values from
<ctype.h> on little endian machines.
(_ISwbit) [__BYTE_ORDER == __LITTLE_ENDIAN]: Correctly transform
bit number. This fixes the real bug and restores the integrity of
the ctype locale file.
* wctype/wcfuncs.c: Change all _ISxxx to _ISwxxx.
* wctype/wcfuncs_l.c: Likewise.
* wctype/wcextra.c: Likewise.
* wctype/wctype_l.c [__BYTE_ORDER == __LITTLE_ENDIAN]: Use correct
byte swapping.
1998-02-09 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/unix/sysv/linux/sparc/sparc32/sysdep.S (errno): Put it
into .bss segment instead of .common, so that aliases on it work.
* sysdeps/unix/sysv/linux/i386/sysdep.S (errno): Add .type and
.size directives, put into .bss segment instead of initializing it
to 4.
1998-02-12 08:00 H.J. Lu <hjl@gnu.org>
* libc.map (gnu_get_libc_release, gnu_get_libc_version): Added.
* version.c (__gnu_get_libc_release, __gnu_get_libc_version): New
functions.
Make names without __ weak aliases.
(__libc_release, __libc_version): Make them static.
* include/gnu/libc-version.h: New file.
* Makefile (headers): Add gnu/libc-version.h.
1998-02-13 Ulrich Drepper <drepper@cygnus.com>
* stdlib/stdlib.h (struct drand48_data): Leave X to user macros
and use x for member name.
Reported by Daniel Lyddy <daniell@cs.berkeley.edu>.
* stdlib/drand48.c: Change according to member name change.
* stdlib/drand48_r.c: Likewise.
* stdlib/lcong48_r.c: Likewise.
* stdlib/lrand48.c: Likewise.
* stdlib/lrand48_r.c: Likewise.
* stdlib/mrand48.c: Likewise.
* stdlib/mrand48_r.c: Likewise.
* stdlib/seed48.c: Likewise.
* stdlib/seed48_r.c: Likewise.
* stdlib/srand48_r.c: Likewise.
1998-02-11 Andreas Jaeger <aj@arthur.rhein-neckar.de>
* nss/test-netdb.c: Add some more test cases.
1998-02-13 11:39 Ulrich Drepper <drepper@cygnus.com>
* libio/iovsscanf.c: Undo last change modifying errno.
1998-02-12 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* stdio-common/vfscanf.c: Never try to read another character
after EOF. Don't decrement read_in after EOF, it wasn't
incremented in the first place.
(NEXT_WIDE_CHAR): Set First, not first.
1998-02-06 07:48 H.J. Lu <hjl@gnu.org>
* db/Makefile ($(inst_libdir)/libndbm.a,
$(inst_libdir)/libndbm.so): New targets.
* db2/Makefile: Likewise.
1998-02-12 08:20 H.J. Lu <hjl@gnu.org>
* sysdeps/gnu/errlist.awk (sys_errlist, sys_nerr): Create weak
aliases if HAVE_ELF or PIC or DO_VERSIONING is not defined.
1998-02-12 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/generic/_G_config.h: Define _G_wchar_t, for C++
<streambuf.h>.
* sysdeps/unix/sysv/linux/_G_config.h: Likewise.
1998-02-11 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* sysdeps/unix/make-syscalls.sh: Fix sed pattern when dealing with
versioned symbols.
1998-02-13 08:14 H.J. Lu <hjl@gnu.org>
* libc.map (_dl_global_scope, _dl_lookup_symbol_skip,
_dl_lookup_versioned_symbol, _dl_lookup_versioned_symbol_skip):
Added for libdl.so.
* elf/rtld.map: New file. Needed to define the GLIBC_2.*
* manual/socket.texi (Host Address Functions): Clarify description
* sysdeps/unix/sysv/linux/alpha/bits/time.h (struct timeval):
Diffstat (limited to 'sysdeps/libm-ieee754/s_exp2.c')
-rw-r--r-- | sysdeps/libm-ieee754/s_exp2.c | 71 |
1 files changed, 39 insertions, 32 deletions
diff --git a/sysdeps/libm-ieee754/s_exp2.c b/sysdeps/libm-ieee754/s_exp2.c index fc3fd2507b..d6f4de02d6 100644 --- a/sysdeps/libm-ieee754/s_exp2.c +++ b/sysdeps/libm-ieee754/s_exp2.c @@ -36,21 +36,23 @@ #include "t_exp2.h" -static const volatile double TWO1000 = 1.071508607186267320948e+301; +static const volatile double TWO1023 = 8.988465674311579539e+307; static const volatile double TWOM1000 = 9.3326361850321887899e-302; double __ieee754_exp2 (double x) { - static const uint32_t a_inf = 0x7f800000; + static const uint32_t a_minf = 0xff800000; + static const double himark = (double) DBL_MAX_EXP; + static const double lomark = (double) (DBL_MIN_EXP - DBL_MANT_DIG - 1) - 1.0; + /* Check for usual case. */ - if (isless (x, (double) DBL_MAX_EXP) - && isgreater (x, (double) (DBL_MIN_EXP - 1))) + if (isless (x, himark) && isgreater (x, lomark)) { static const float TWO43 = 8796093022208.0; - int tval; - double rx, x22; - union ieee754_double ex2_u; + int tval, unsafe; + double rx, x22, result; + union ieee754_double ex2_u, scale_u; fenv_t oldenv; feholdexcept (&oldenv); @@ -95,37 +97,42 @@ __ieee754_exp2 (double x) /* 3. Compute ex2 = 2^(t/512+e+ex). */ ex2_u.d = exp2_accuratetable[tval & 511]; - ex2_u.ieee.exponent += tval >> 9; + tval >>= 9; + unsafe = abs(tval) >= -DBL_MIN_EXP - 1; + ex2_u.ieee.exponent += tval >> unsafe; + scale_u.d = 1.0; + scale_u.ieee.exponent += tval - (tval >> unsafe); /* 4. Approximate 2^x2 - 1, using a fourth-degree polynomial, - 2^x2 ~= sum(k=0..4 | (x2 * ln(2))^k / k! ) + - so - 2^x2 - 1 ~= sum(k=1..4 | (x2 * ln(2))^k / k! ) - with error less than 2^(1/1024) * (x2 * ln(2))^5 / 5! < 1.2e-18. */ + with maximum error in [-2^-10-2^-30,2^-10+2^-30] + less than 10^-19. */ - x22 = (((.0096181291076284772 - * x + .055504108664821580) - * x + .240226506959100712) - * x + .69314718055994531) * ex2_u.d; + x22 = (((.0096181293647031180 + * x + .055504110254308625) + * x + .240226506959100583) + * x + .69314718055994495) * ex2_u.d; /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex). */ fesetenv (&oldenv); - /* Need to check: does this set FE_INEXACT correctly? */ - return x22 * x + ex2_u.d; + result = x22 * x + ex2_u.d; + + if (!unsafe) + return result; + else + return result * scale_u.d; + } + /* Exceptional cases: */ + else if (isless (x, himark)) + { + if (x == *(const float *) &a_minf) + /* e^-inf == 0, with no error. */ + return 0; + else + /* Underflow */ + return TWOM1000 * TWOM1000; } - /* 2^inf == inf, with no error. */ - else if (x == *(const float *) &a_inf) - return x; - /* Check for overflow. */ - else if (isgreaterequal (x, (double) DBL_MAX_EXP)) - return TWO1000 * TWO1000; - /* And underflow (including -inf). */ - else if (isless (x, (double) (DBL_MIN_EXP - DBL_MANT_DIG))) - return TWOM1000 * TWOM1000; - /* Maybe the result needs to be a denormalised number... */ - else if (!isnan (x)) - return __ieee754_exp2 (x + 1000.0) * TWOM1000; - else /* isnan(x) */ - return x + x; + else + /* Return x, if x is a NaN or Inf; or overflow, otherwise. */ + return TWO1023*x; } |