[Emacs-diffs] /srv/bzr/emacs/trunk r109974: Simplify, document, and port floating-point.

[Paul Eggert]

------------------------------------------------------------
revno: 109974
committer: Paul Eggert <address@hidden>
branch nick: trunk
timestamp: Mon 2012-09-10 19:28:27 -0700
message:
  Simplify, document, and port floating-point.
  
  The porting part of this patch fixes bugs on non-IEEE platforms
  with frexp, ldexp, logb.
  * admin/CPP-DEFINES (HAVE_CBRT, HAVE_LOGB, logb): Remove.
  * configure.ac (logb, cbrt): Do not check for these functions,
  as they are not being used.
  * doc/lispref/numbers.texi (Float Basics, Arithmetic Operations, Math 
Functions):
  Document that / and mod (with floating point arguments), along
  with asin, acos, log, log10, expt and sqrt, return special values
  instead of signaling exceptions.
  (Float Basics): Document that logb operates on the absolute value
  of its argument.
  (Math Functions): Document that (log ARG BASE) also returns NaN if
  BASE is negative.  Document that (expt X Y) returns NaN if X is a
  finite negative number and Y a finite non-integer.
  * etc/NEWS: Document NaNs versus signaling-error change.
  * src/data.c, src/lisp.h (Qdomain_error, Qsingularity_error, 
Qunderflow_error):
  Now static.
  * src/floatfns.c: Simplify discussion of functions that Emacs doesn't
  support, by removing commented-out code and briefly listing the
  C89 functions excluded.  The commented-out stuff was confusing
  maintenance, e.g., we thought we needed cbrt but it was commented out.
  (logb): Remove decl; no longer needed.
  (isfinite): New macro, if not already supplied.
  (isnan): Don't replace any existing macro.
  (Ffrexp, Fldexp): Define even if !HAVE_COPYSIGN, as frexp and ldexp
  are present on all C89 platforms.
  (Ffrexp): Do not special-case zero, as frexp does the right thing
  for that case.
  (Flogb): Do not use logb, as it doesn't have the desired meaning
  on hosts that use non-base-2 floating point.  Instead, stick with
  frexp, which is C89 anyway.  Do not pass an infinity or a NaN to
  frexp, to avoid getting an unspecified result.
modified:
  ChangeLog
  admin/CPP-DEFINES
  admin/ChangeLog
  configure.ac
  doc/lispref/ChangeLog
  doc/lispref/numbers.texi
  etc/ChangeLog
  etc/NEWS
  src/ChangeLog
  src/data.c
  src/floatfns.c
  src/lisp.h

=== modified file 'ChangeLog'
--- a/ChangeLog 2012-09-10 01:03:27 +0000
+++ b/ChangeLog 2012-09-11 02:28:27 +0000
@@ -1,3 +1,9 @@
+2012-09-11  Paul Eggert  <address@hidden>
+
+       Simplify, document, and port floating-point (Bug#12381).
+       * configure.ac (logb, cbrt): Do not check for these functions,
+       as they are not being used.
+
 2012-09-10  Paul Eggert  <address@hidden>
 
        Improve robustness of 'make bootstrap' (Bug#12376).

=== modified file 'admin/CPP-DEFINES'
--- a/admin/CPP-DEFINES 2012-09-09 16:06:33 +0000
+++ b/admin/CPP-DEFINES 2012-09-11 02:28:27 +0000
@@ -120,7 +120,6 @@
 HAVE_BDFFONT
 HAVE_BOXES
 HAVE_C99_STRTOLD
-HAVE_CBRT
 HAVE_CFMAKERAW
 HAVE_CFSETSPEED
 HAVE_CLOCK_GETTIME
@@ -251,7 +250,6 @@
 HAVE_LINUX_VERSION_H
 HAVE_LOCALTIME_R
 HAVE_LOCAL_SOCKETS
-HAVE_LOGB
 HAVE_LONG_FILE_NAMES
 HAVE_LONG_LONG_INT
 HAVE_LRAND48
@@ -574,7 +572,6 @@
 isatty
 kill
 link
-logb
 lseek
 mkdir
 mktemp
@@ -616,7 +613,6 @@
 getpid
 index
 isatty
-logb
 lseek
 mkdir
 mktemp

=== modified file 'admin/ChangeLog'
--- a/admin/ChangeLog   2012-09-09 16:06:33 +0000
+++ b/admin/ChangeLog   2012-09-11 02:28:27 +0000
@@ -1,3 +1,8 @@
+2012-09-11  Paul Eggert  <address@hidden>
+
+       Simplify, document, and port floating-point (Bug#12381).
+       * CPP-DEFINES (HAVE_CBRT, HAVE_LOGB, logb): Remove.
+
 2012-09-09  Paul Eggert  <address@hidden>
 
        Assume C89 or later for math functions (Bug#12381).

=== modified file 'configure.ac'
--- a/configure.ac      2012-09-09 16:06:33 +0000
+++ b/configure.ac      2012-09-11 02:28:27 +0000
@@ -2689,8 +2689,8 @@
   AC_DEFINE(HAVE_H_ERRNO, 1, [Define to 1 if netdb.h declares h_errno.])
 fi
 
-# fmod, logb, and frexp are found in -lm on most systems.
-# On HPUX 9.01, -lm does not contain logb, so check for sqrt.
+# sqrt and other floating-point functions such as fmod and frexp
+# are found in -lm on most systems.
 AC_CHECK_LIB(m, sqrt)
 
 # Check for mail-locking functions in a "mail" library.  Probably this should
@@ -2770,7 +2770,7 @@
 
 AC_CHECK_FUNCS(gethostname \
 closedir getrusage get_current_dir_name \
-lrand48 logb cbrt setsid \
+lrand48 setsid \
 fpathconf select euidaccess getpagesize setlocale \
 utimes getrlimit setrlimit setpgid getcwd shutdown getaddrinfo \
 __fpending strsignal setitimer \

=== modified file 'doc/lispref/ChangeLog'
--- a/doc/lispref/ChangeLog     2012-09-09 07:50:45 +0000
+++ b/doc/lispref/ChangeLog     2012-09-11 02:28:27 +0000
@@ -1,3 +1,16 @@
+2012-09-11  Paul Eggert  <address@hidden>
+
+       Simplify, document, and port floating-point (Bug#12381).
+       * numbers.texi (Float Basics, Arithmetic Operations, Math Functions):
+       Document that / and mod (with floating point arguments), along
+       with asin, acos, log, log10, expt and sqrt, return special values
+       instead of signaling exceptions.
+       (Float Basics): Document that logb operates on the absolute value
+       of its argument.
+       (Math Functions): Document that (log ARG BASE) also returns NaN if
+       BASE is negative.  Document that (expt X Y) returns NaN if X is a
+       finite negative number and Y a finite non-integer.
+
 2012-09-09  Chong Yidong  <address@hidden>
 
        * lists.texi (Sets And Lists): Explain that the return value for

=== modified file 'doc/lispref/numbers.texi'
--- a/doc/lispref/numbers.texi  2012-09-01 01:04:26 +0000
+++ b/doc/lispref/numbers.texi  2012-09-11 02:28:27 +0000
@@ -196,6 +196,14 @@
 correct answer.  For example, @code{(/ 0.0 0.0)} returns a NaN.  (NaN
 values can also carry a sign, but for practical purposes there's no
 significant difference between different NaN values in Emacs Lisp.)
+
+When a function is documented to return a NaN, it returns an
+implementation-defined value when Emacs is running on one of the
+now-rare platforms that do not use @acronym{IEEE} floating point.  For
+example, @code{(log -1.0)} typically returns a NaN, but on
address@hidden platforms it returns an implementation-defined
+value.
+
 Here are the read syntaxes for these special floating point values:
 
 @table @asis
@@ -241,7 +249,7 @@
 
 @defun logb number
 This function returns the binary exponent of @var{number}.  More
-precisely, the value is the logarithm of @var{number} base 2, rounded
+precisely, the value is the logarithm of |@var{number}| base 2, rounded
 down to an integer.
 
 @example
@@ -694,7 +702,8 @@
 quotient downward (towards minus infinity) to an integer, and uses that
 quotient to compute the remainder.
 
-An @code{arith-error} results if @var{divisor} is 0.
+If @var{divisor} is zero, @code{mod} signals an @code{arith-error}
+error if both arguments are integers, and returns a NaN otherwise.
 
 @example
 @group
@@ -1096,8 +1105,8 @@
 @tex
 @math{\pi/2}
 @end tex
-(inclusive) whose sine is @var{arg}; if, however, @var{arg} is out of
-range (outside address@hidden, 1]), it signals a @code{domain-error} error.
+(inclusive) whose sine is @var{arg}.  If @var{arg} is out of range
+(outside address@hidden, 1]), @code{asin} returns a NaN.
 @end defun
 
 @defun acos arg
@@ -1108,8 +1117,8 @@
 @tex
 @math{\pi}
 @end tex
-(inclusive) whose cosine is @var{arg}; if, however, @var{arg} is out
-of range (outside address@hidden, 1]), it signals a @code{domain-error} error.
+(inclusive) whose cosine is @var{arg}.  If @var{arg} is out of range
+(outside address@hidden, 1]), @code{acos} returns a NaN.
 @end defun
 
 @defun atan y &optional x
@@ -1141,8 +1150,8 @@
 @defun log arg &optional base
 This function returns the logarithm of @var{arg}, with base
 @var{base}.  If you don't specify @var{base}, the natural base
address@hidden is used.  If @var{arg} is negative, it signals a
address@hidden error.
address@hidden is used.  If @var{arg} or @var{base} is negative, @code{log}
+returns a NaN.
 @end defun
 
 @ignore
@@ -1160,21 +1169,21 @@
 @end ignore
 
 @defun log10 arg
-This function returns the logarithm of @var{arg}, with base 10.  If
address@hidden is negative, it signals a @code{domain-error} error.
address@hidden(log10 @var{x})} @equiv{} @code{(log @var{x} 10)}, at least
-approximately.
+This function returns the logarithm of @var{arg}, with base 10:
address@hidden(log10 @var{x})} @equiv{} @code{(log @var{x} 10)}.
 @end defun
 
 @defun expt x y
 This function returns @var{x} raised to power @var{y}.  If both
 arguments are integers and @var{y} is positive, the result is an
 integer; in this case, overflow causes truncation, so watch out.
+If @var{x} is a finite negative number and @var{y} is a finite
+non-integer, @code{expt} returns a NaN.
 @end defun
 
 @defun sqrt arg
 This returns the square root of @var{arg}.  If @var{arg} is negative,
-it signals a @code{domain-error} error.
address@hidden returns a NaN.
 @end defun
 
 In addition, Emacs defines the following common mathematical

=== modified file 'etc/ChangeLog'
--- a/etc/ChangeLog     2012-09-04 18:29:04 +0000
+++ b/etc/ChangeLog     2012-09-11 02:28:27 +0000
@@ -1,3 +1,8 @@
+2012-09-11  Paul Eggert  <address@hidden>
+
+       Simplify, document, and port floating-point (Bug#12381).
+       * NEWS: Document NaNs versus signaling-error change.
+
 2012-09-04  Paul Eggert  <address@hidden>
 
        Give more-useful info on a fatal error (Bug#12328).

=== modified file 'etc/NEWS'
--- a/etc/NEWS  2012-09-10 19:22:53 +0000
+++ b/etc/NEWS  2012-09-11 02:28:27 +0000
@@ -729,6 +729,14 @@
 must be in the range 1000..9999.  It now works with any year supported
 by the underlying C implementation.
 
+** Floating point
+
+*** When floating point functions such as `log' are given invalid
+arguments, e.g., (log -1.0), they now uniformly return special values
+such as NaNs instead of signaling errors.  Previously, these functions
+returned NaNs on some platforms but signaled errors on others.  The affected
+functions are acos, asin, tan, exp, expt, log, log10, sqrt, and mod.
+
 ** New function file-name-base.
 
 ** New function `tty-top-frame' returns the topmost frame of a text terminal.

=== modified file 'src/ChangeLog'
--- a/src/ChangeLog     2012-09-11 01:20:56 +0000
+++ b/src/ChangeLog     2012-09-11 02:28:27 +0000
@@ -1,5 +1,26 @@
 2012-09-11  Paul Eggert  <address@hidden>
 
+       Simplify, document, and port floating-point (Bug#12381).
+       The porting part of this patch fixes bugs on non-IEEE platforms
+       with frexp, ldexp, logb.
+       * data.c, lisp.h (Qdomain_error, Qsingularity_error, Qunderflow_error):
+       Now static.
+       * floatfns.c: Simplify discussion of functions that Emacs doesn't
+       support, by removing commented-out code and briefly listing the
+       C89 functions excluded.  The commented-out stuff was confusing
+       maintenance, e.g., we thought we needed cbrt but it was commented out.
+       (logb): Remove decl; no longer needed.
+       (isfinite): New macro, if not already supplied.
+       (isnan): Don't replace any existing macro.
+       (Ffrexp, Fldexp): Define even if !HAVE_COPYSIGN, as frexp and ldexp
+       are present on all C89 platforms.
+       (Ffrexp): Do not special-case zero, as frexp does the right thing
+       for that case.
+       (Flogb): Do not use logb, as it doesn't have the desired meaning
+       on hosts that use non-base-2 floating point.  Instead, stick with
+       frexp, which is C89 anyway.  Do not pass an infinity or a NaN to
+       frexp, to avoid getting an unspecified result.
+
        * xdisp.c (Qinhibit_debug_on_message): Now static.
 
 2012-09-10  Jan Djärv  <address@hidden>

=== modified file 'src/data.c'
--- a/src/data.c        2012-09-09 16:06:33 +0000
+++ b/src/data.c        2012-09-11 02:28:27 +0000
@@ -71,8 +71,8 @@
 Lisp_Object Qcdr;
 static Lisp_Object Qad_advice_info, Qad_activate_internal;
 
-Lisp_Object Qrange_error, Qdomain_error, Qsingularity_error;
-Lisp_Object Qoverflow_error, Qunderflow_error;
+static Lisp_Object Qdomain_error, Qsingularity_error, Qunderflow_error;
+Lisp_Object Qrange_error, Qoverflow_error;
 
 Lisp_Object Qfloatp;
 Lisp_Object Qnumberp, Qnumber_or_marker_p;

=== modified file 'src/floatfns.c'
--- a/src/floatfns.c    2012-09-09 16:06:33 +0000
+++ b/src/floatfns.c    2012-09-11 02:28:27 +0000
@@ -22,9 +22,10 @@
 along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 
-/* C89 requires only these math.h functions:
-   acos, asin, atan, atan2, ceil, cos, cosh, exp, fabs, floor, fmod,
-   frexp, ldexp, log, log10, modf, pow, sin, sinh, sqrt, tan, tanh.
+/* C89 requires only the following math.h functions, and Emacs omits
+   the starred functions since we haven't found a use for them:
+   acos, asin, atan, atan2, ceil, cos, *cosh, exp, fabs, floor, fmod,
+   frexp, ldexp, log, log10, *modf, pow, sin, *sinh, sqrt, tan, *tanh.
  */
 
 #include <config.h>
@@ -42,10 +43,12 @@
 
 #include <math.h>
 
-/* This declaration is omitted on some systems, like Ultrix.  */
-#if !defined (HPUX) && defined (HAVE_LOGB) && !defined (logb)
-extern double logb (double);
-#endif /* not HPUX and HAVE_LOGB and no logb macro */
+#ifndef isfinite
+# define isfinite(x) ((x) - (x) == 0)
+#endif
+#ifndef isnan
+# define isnan(x) ((x) != (x))
+#endif
 
 /* Extract a Lisp number as a `double', or signal an error.  */
 
@@ -126,9 +129,6 @@
   return make_float (d);
 }
 
-#undef isnan
-#define isnan(x) ((x) != (x))
-
 DEFUN ("isnan", Fisnan, Sisnan, 1, 1, 0,
        doc: /* Return non nil iff argument X is a NaN.  */)
   (Lisp_Object x)
@@ -153,6 +153,7 @@
 
   return make_float (copysign (f1, f2));
 }
+#endif
 
 DEFUN ("frexp", Ffrexp, Sfrexp, 1, 1, 0,
        doc: /* Get significand and exponent of a floating point number.
@@ -167,15 +168,9 @@
   (Lisp_Object x)
 {
   double f = XFLOATINT (x);
-
-  if (f == 0.0)
-    return Fcons (make_float (0.0), make_number (0));
-  else
-    {
-      int exponent;
-      double sgnfcand = frexp (f, &exponent);
-      return Fcons (make_float (sgnfcand), make_number (exponent));
-    }
+  int exponent;
+  double sgnfcand = frexp (f, &exponent);
+  return Fcons (make_float (sgnfcand), make_number (exponent));
 }
 
 DEFUN ("ldexp", Fldexp, Sldexp, 1, 2, 0,
@@ -187,118 +182,6 @@
   CHECK_NUMBER (exponent);
   return make_float (ldexp (XFLOATINT (sgnfcand), XINT (exponent)));
 }
-#endif
-
-#if 0 /* Leave these out unless we find there's a reason for them.  */
-
-DEFUN ("bessel-j0", Fbessel_j0, Sbessel_j0, 1, 1, 0,
-       doc: /* Return the bessel function j0 of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = j0 (d);
-  return make_float (d);
-}
-
-DEFUN ("bessel-j1", Fbessel_j1, Sbessel_j1, 1, 1, 0,
-       doc: /* Return the bessel function j1 of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = j1 (d);
-  return make_float (d);
-}
-
-DEFUN ("bessel-jn", Fbessel_jn, Sbessel_jn, 2, 2, 0,
-       doc: /* Return the order N bessel function output jn of ARG.
-The first arg (the order) is truncated to an integer.  */)
-  (Lisp_Object n, Lisp_Object arg)
-{
-  int i1 = extract_float (n);
-  double f2 = extract_float (arg);
-
-  f2 = jn (i1, f2);
-  return make_float (f2);
-}
-
-DEFUN ("bessel-y0", Fbessel_y0, Sbessel_y0, 1, 1, 0,
-       doc: /* Return the bessel function y0 of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = y0 (d);
-  return make_float (d);
-}
-
-DEFUN ("bessel-y1", Fbessel_y1, Sbessel_y1, 1, 1, 0,
-       doc: /* Return the bessel function y1 of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = y1 (d);
-  return make_float (d);
-}
-
-DEFUN ("bessel-yn", Fbessel_yn, Sbessel_yn, 2, 2, 0,
-       doc: /* Return the order N bessel function output yn of ARG.
-The first arg (the order) is truncated to an integer.  */)
-  (Lisp_Object n, Lisp_Object arg)
-{
-  int i1 = extract_float (n);
-  double f2 = extract_float (arg);
-
-  f2 = yn (i1, f2);
-  return make_float (f2);
-}
-
-#endif
-
-#if 0 /* Leave these out unless we see they are worth having.  */
-
-DEFUN ("erf", Ferf, Serf, 1, 1, 0,
-       doc: /* Return the mathematical error function of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = erf (d);
-  return make_float (d);
-}
-
-DEFUN ("erfc", Ferfc, Serfc, 1, 1, 0,
-       doc: /* Return the complementary error function of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = erfc (d);
-  return make_float (d);
-}
-
-DEFUN ("log-gamma", Flog_gamma, Slog_gamma, 1, 1, 0,
-       doc: /* Return the log gamma of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = lgamma (d);
-  return make_float (d);
-}
-
-DEFUN ("cube-root", Fcube_root, Scube_root, 1, 1, 0,
-       doc: /* Return the cube root of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-#ifdef HAVE_CBRT
-  d = cbrt (d);
-#else
-  if (d >= 0.0)
-    d = pow (d, 1.0/3.0);
-  else
-    d = -pow (-d, 1.0/3.0);
-#endif
-  return make_float (d);
-}
-
-#endif
 
 DEFUN ("exp", Fexp, Sexp, 1, 1, 0,
        doc: /* Return the exponential base e of ARG.  */)
@@ -383,63 +266,6 @@
   return make_float (d);
 }
 
-#if 0 /* Not clearly worth adding.  */
-
-DEFUN ("acosh", Facosh, Sacosh, 1, 1, 0,
-       doc: /* Return the inverse hyperbolic cosine of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = acosh (d);
-  return make_float (d);
-}
-
-DEFUN ("asinh", Fasinh, Sasinh, 1, 1, 0,
-       doc: /* Return the inverse hyperbolic sine of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = asinh (d);
-  return make_float (d);
-}
-
-DEFUN ("atanh", Fatanh, Satanh, 1, 1, 0,
-       doc: /* Return the inverse hyperbolic tangent of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = atanh (d);
-  return make_float (d);
-}
-
-DEFUN ("cosh", Fcosh, Scosh, 1, 1, 0,
-       doc: /* Return the hyperbolic cosine of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = cosh (d);
-  return make_float (d);
-}
-
-DEFUN ("sinh", Fsinh, Ssinh, 1, 1, 0,
-       doc: /* Return the hyperbolic sine of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = sinh (d);
-  return make_float (d);
-}
-
-DEFUN ("tanh", Ftanh, Stanh, 1, 1, 0,
-       doc: /* Return the hyperbolic tangent of ARG.  */)
-  (Lisp_Object arg)
-{
-  double d = extract_float (arg);
-  d = tanh (d);
-  return make_float (d);
-}
-#endif
-
 DEFUN ("abs", Fabs, Sabs, 1, 1, 0,
        doc: /* Return the absolute value of ARG.  */)
   (register Lisp_Object arg)
@@ -477,16 +303,15 @@
 
   if (f == 0.0)
     value = MOST_NEGATIVE_FIXNUM;
-  else
+  else if (isfinite (f))
     {
-#ifdef HAVE_LOGB
-      value = logb (f);
-#else
       int ivalue;
       frexp (f, &ivalue);
       value = ivalue - 1;
-#endif
     }
+  else
+    value = MOST_POSITIVE_FIXNUM;
+
   XSETINT (val, value);
   return val;
 }
@@ -719,27 +544,9 @@
   defsubr (&Sisnan);
 #ifdef HAVE_COPYSIGN
   defsubr (&Scopysign);
+#endif
   defsubr (&Sfrexp);
   defsubr (&Sldexp);
-#endif
-#if 0
-  defsubr (&Sacosh);
-  defsubr (&Sasinh);
-  defsubr (&Satanh);
-  defsubr (&Scosh);
-  defsubr (&Ssinh);
-  defsubr (&Stanh);
-  defsubr (&Sbessel_y0);
-  defsubr (&Sbessel_y1);
-  defsubr (&Sbessel_yn);
-  defsubr (&Sbessel_j0);
-  defsubr (&Sbessel_j1);
-  defsubr (&Sbessel_jn);
-  defsubr (&Serf);
-  defsubr (&Serfc);
-  defsubr (&Slog_gamma);
-  defsubr (&Scube_root);
-#endif
   defsubr (&Sfceiling);
   defsubr (&Sffloor);
   defsubr (&Sfround);

=== modified file 'src/lisp.h'
--- a/src/lisp.h        2012-09-10 01:17:23 +0000
+++ b/src/lisp.h        2012-09-11 02:28:27 +0000
@@ -2559,8 +2559,7 @@
 
 extern Lisp_Object Qcdr;
 
-extern Lisp_Object Qrange_error, Qdomain_error, Qsingularity_error;
-extern Lisp_Object Qoverflow_error, Qunderflow_error;
+extern Lisp_Object Qrange_error, Qoverflow_error;
 
 extern Lisp_Object Qfloatp;
 extern Lisp_Object Qnumberp, Qnumber_or_marker_p;