Commit Graph

16 Commits

Author SHA1 Message Date
David Schultz
7cd50f4d94 Eliminate some warnings. 2008-02-22 02:26:51 +00:00
Bruce Evans
e95cc9b700 Fix tgamma() on some special args:
(1) tgamma(-Inf) returned +Inf and failed to raise any exception, but
    should always have raised an exception, and should behave like
    tgamma(negative integer).
(2) tgamma(negative integer) returned +Inf and raised divide-by-zero,
    but should return NaN and raise "invalid" on any IEEEish system.
(3) About half of the 2**52 negative intgers between -2**53 and -2**52
    were misclassified as non-integers by using floor(x + 0.5) to round
    to nearest, so tgamma(x) was wrong (+-0 instead of +Inf and now NaN)
    on these args.  The floor() expression is hard to use since rounding
    of (x + 0.5) may give x or x + 1, depending on |x| and the current
    rounding mode.  The fixed version uses ceil(x) to classify x before
    operating on x and ends up being more efficient since ceil(x) is
    needed anyway.
(4) On at least the problematic args in (3), tgamma() raised a spurious
    inexact.
(5) tgamma(large positive) raised divide-by-zero but should raise overflow.
(6) tgamma(+Inf) raised divide-by-zero but should not raise any exception.
(7) Raise inexact for tiny |x| in a way that has some chance of not being
    optimized away.

The fix for (5) and (6), and probably for (2), also prevents -O optimizing
away the exception.

PR:		112180 (2)
Standards:	Annex F in C99 (IEC 60559 binding) requires (1), (2) and (6).
2007-05-02 15:24:49 +00:00
Bruce Evans
dd936b27fc Document (in a comment) the current (slightly broken) handling of special
values in more detail, and change the style of this comment to be closer
to fdlibm and C99:
- tgamma(-Inf) was undocumented and is wrong (+Inf, should be NaN)
- tgamma(negative integer) is as intended (+Inf) but not best for IEEE-754
  (NaN)
- tgamma(-0) was documented as being wrong (+Inf) but was correct (-Inf)
- documentation of setting of exceptions (overflow, etc.) was more
  complete here than in most of libm, but was further from matching
  the actual setting than in most of libm, due to various bugs here
  (primarily, always evaluating +Inf one/zero and getting unwanted
  divide-by-zero exceptions from this).  Now the actual behaviour with
  gcc -O0 is documented.  Optimization still breaks setting of exceptions
  all over libm, so nothing can depend on this working.
- tgamma(NaN)'s exception was documented as being wrong (invalid) but was
  correct (no exception with IEEEish NaNs).

Finish (?) rev.1.5.  gamma was not renamed to tgamma in one place.

Finish (?) rev.1.6.  errno.h was not completely removed.
2007-05-02 13:49:28 +00:00
Bruce Evans
3f1a8f462c Removed an unused declaration which was so old that it wasn't a prototype
and thus just broke building at any nonzero WARNS level.

Fixed nearby style bugs.
2005-11-18 05:03:12 +00:00
Bruce Evans
0b42281ee9 Fixed aliasing bugs in TRUNC() by using the fdlibm macros for access
to doubles as bits.  fdlibm-1.1 had similar aliasing bugs, but these
were fixed by NetBSD or Cygnus before a modified version of fdlibm was
imported in 1994.  TRUNC() is only used by tgamma() and some
implementation-detail functions.  The aliasing bugs were detected by
compiling with gcc -O2 but don't seem to have broken tgamma() on i386's
or amd64's.  They broke my modified version of tgamma().

Moved the definition of TRUNC() to mathimpl.h so that it can be fixed
in one place, although the general version is even slower than necessary
because it has to operate on pointers to volatiles to handle its arg
sometimes being volatile.  Inefficiency of the fdlibm macros slows
down libm generally, and tgamma() is a relatively unimportant part of
libm.  The macros act as if on 32-bit words in memory, so they are
hard to optimize to direct actions on 64-bit double registers for
(non-i386) machines where this is possible.  The optimization is too
hard for gcc on amd64's, and declaring variables as volatile makes it
impossible.
2005-09-19 11:28:19 +00:00
David Schultz
527055d12f GC unused declaration 2004-12-16 20:40:49 +00:00
David Schultz
17519e9b79 Cosmetic changes only:
- style
- remove unused variables
- de-support VAX

Inspired by:	bin/42388
2004-12-16 20:40:37 +00:00
David Schultz
6955d806c0 Remove some kludges designed to ensure that the compiler didn't round
constants the wrong way on the VAX.  Instead, use C99 hexadecimal
floating-point constants, which are guaranteed to be exact on binary
IEEE machines.  (The correct hexadecimal values were already provided
in the source, but not used.)  Also, convert the constants to
lowercase to work around a gcc bug that wasn't fixed until gcc 3.4.0.

Prompted by:	stefanf
2004-05-17 01:04:37 +00:00
Jens Schweikhardt
9d5abbddbf Correct typos, mostly s/ a / an / where appropriate. Some whitespace cleanup,
especially in troff files.
2003-01-01 18:49:04 +00:00
Alfred Perlstein
a82bbc730e Assume __STDC__, remove non-__STDC__ code.
Submitted by: keramida
2002-05-28 17:03:12 +00:00
Bruce Evans
46d7c2979e Resurrect Lite1's gamma() as C99's tgamma(). Minimal changes. 2002-03-26 11:59:29 +00:00
David E. O'Brien
69160b1eb7 Remove __P() usage. 2002-03-21 23:54:04 +00:00
David E. O'Brien
84c63a156a Fix SCM ID's. 2002-03-21 18:06:09 +00:00
Matthew Dillon
65c6735764 Add __FBSDID()s to libm 2001-09-30 21:53:45 +00:00
Rodney W. Grimes
6c06b4e2aa Remove trailing whitespace. 1995-05-30 05:51:47 +00:00
Rodney W. Grimes
58f0484fa2 BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00