(Frem) [MSDOS]: use `fmod', not `drem'. Put in config.h?

[bpt/emacs.git] / src / floatfns.c

/* Primitive operations on floating point for GNU Emacs Lisp interpreter.
   Copyright (C) 1988, 1993 Free Software Foundation, Inc.

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


/* ANSI C requires only these float functions:
   acos, asin, atan, atan2, ceil, cos, cosh, exp, fabs, floor, fmod,
   frexp, ldexp, log, log10, modf, pow, sin, sinh, sqrt, tan, tanh.

   Define HAVE_INVERSE_HYPERBOLIC if you have acosh, asinh, and atanh.
   Define HAVE_CBRT if you have cbrt.
   Define HAVE_RINT if you have rint.
   If you don't define these, then the appropriate routines will be simulated.

   Define HAVE_MATHERR if on a system supporting the SysV matherr callback.
   (This should happen automatically.)

   Define FLOAT_CHECK_ERRNO if the float library routines set errno.
   This has no effect if HAVE_MATHERR is defined.

   Define FLOAT_CATCH_SIGILL if the float library routines signal SIGILL.
   (What systems actually do this?  Please let us know.)

   Define FLOAT_CHECK_DOMAIN if the float library doesn't handle errors by
   either setting errno, or signalling SIGFPE/SIGILL.  Otherwise, domain and
   range checking will happen before calling the float routines.  This has
   no effect if HAVE_MATHERR is defined (since matherr will be called when
   a domain error occurs.)
 */

#include <signal.h>

#include <config.h>
#include "lisp.h"
#include "syssignal.h"

Lisp_Object Qarith_error;

#ifdef LISP_FLOAT_TYPE

#if 0 /* That is untrue--XINT is used below, and it uses INTBITS.
	 What in the world is values.h, anyway?  */
#ifdef MSDOS
/* These are redefined in <values.h> and not used here */
#undef INTBITS
#undef LONGBITS
#undef SHORTBITS
#endif
#endif

/* Work around a problem that happens because math.h on hpux 7
   defines two static variables--which, in Emacs, are not really static,
   because `static' is defined as nothing.  The problem is that they are
   defined both here and in lread.c.
   These macros prevent the name conflict.  */
#if defined (HPUX) && !defined (HPUX8)
#define _MAXLDBL floatfns_maxldbl
#define _NMAXLDBL floatfns_nmaxldbl
#endif

#include <math.h>

/* This declaration is omitted on some systems, like Ultrix.  */
#if !defined (hpux) && defined (HAVE_LOGB)
extern double logb ();
#endif /* !hpux && HAVE_LOGB */

#ifndef MSDOS
#if defined(DOMAIN) && defined(SING) && defined(OVERFLOW)
    /* If those are defined, then this is probably a `matherr' machine. */
# ifndef HAVE_MATHERR
#  define HAVE_MATHERR
# endif
#endif
#endif

#ifdef NO_MATHERR
#undef HAVE_MATHERR
#endif

#ifdef HAVE_MATHERR
# ifdef FLOAT_CHECK_ERRNO
#  undef FLOAT_CHECK_ERRNO
# endif
# ifdef FLOAT_CHECK_DOMAIN
#  undef FLOAT_CHECK_DOMAIN
# endif
#endif

#ifndef NO_FLOAT_CHECK_ERRNO
#define FLOAT_CHECK_ERRNO
#endif

#ifdef FLOAT_CHECK_ERRNO
# include <errno.h>

extern int errno;
#endif

/* Avoid traps on VMS from sinh and cosh.
   All the other functions set errno instead.  */

#ifdef VMS
#undef cosh
#undef sinh
#define cosh(x) ((exp(x)+exp(-x))*0.5)
#define sinh(x) ((exp(x)-exp(-x))*0.5)
#endif /* VMS */

#ifndef HAVE_RINT
#define rint(x) (floor((x)+0.5))
#endif

static SIGTYPE float_error ();

/* Nonzero while executing in floating point.
   This tells float_error what to do.  */

static int in_float;

/* If an argument is out of range for a mathematical function,
   here is the actual argument value to use in the error message.  */

static Lisp_Object float_error_arg, float_error_arg2;

static char *float_error_fn_name;

/* Evaluate the floating point expression D, recording NUM
   as the original argument for error messages.
   D is normally an assignment expression.
   Handle errors which may result in signals or may set errno.

   Note that float_error may be declared to return void, so you can't
   just cast the zero after the colon to (SIGTYPE) to make the types
   check properly.  */

#ifdef FLOAT_CHECK_ERRNO
#define IN_FLOAT(d, name, num)				\
  do {							\
    float_error_arg = num;				\
    float_error_fn_name = name;				\
    in_float = 1; errno = 0; (d); in_float = 0;		\
    switch (errno) {					\
    case 0: break;					\
    case EDOM:	 domain_error (float_error_fn_name, float_error_arg);	\
    case ERANGE: range_error (float_error_fn_name, float_error_arg);	\
    default:	 arith_error (float_error_fn_name, float_error_arg);	\
    }							\
  } while (0)
#define IN_FLOAT2(d, name, num, num2)			\
  do {							\
    float_error_arg = num;				\
    float_error_arg2 = num2;				\
    float_error_fn_name = name;				\
    in_float = 1; errno = 0; (d); in_float = 0;		\
    switch (errno) {					\
    case 0: break;					\
    case EDOM:	 domain_error (float_error_fn_name, float_error_arg);	\
    case ERANGE: range_error (float_error_fn_name, float_error_arg);	\
    default:	 arith_error (float_error_fn_name, float_error_arg);	\
    }							\
  } while (0)
#else
#define IN_FLOAT(d, name, num) (in_float = 1, (d), in_float = 0)
#define IN_FLOAT2(d, name, num, num2) (in_float = 1, (d), in_float = 0)
#endif

#define arith_error(op,arg) \
  Fsignal (Qarith_error, Fcons (build_string ((op)), Fcons ((arg), Qnil)))
#define range_error(op,arg) \
  Fsignal (Qrange_error, Fcons (build_string ((op)), Fcons ((arg), Qnil)))
#define domain_error(op,arg) \
  Fsignal (Qdomain_error, Fcons (build_string ((op)), Fcons ((arg), Qnil)))
#define domain_error2(op,a1,a2) \
  Fsignal (Qdomain_error, Fcons (build_string ((op)), Fcons ((a1), Fcons ((a2), Qnil))))

/* Extract a Lisp number as a `double', or signal an error.  */

double
extract_float (num)
     Lisp_Object num;
{
  CHECK_NUMBER_OR_FLOAT (num, 0);

  if (XTYPE (num) == Lisp_Float)
    return XFLOAT (num)->data;
  return (double) XINT (num);
}
\f
/* Trig functions.  */

DEFUN ("acos", Facos, Sacos, 1, 1, 0,
  "Return the inverse cosine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d > 1.0 || d < -1.0)
    domain_error ("acos", arg);
#endif
  IN_FLOAT (d = acos (d), "acos", arg);
  return make_float (d);
}

DEFUN ("asin", Fasin, Sasin, 1, 1, 0,
  "Return the inverse sine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d > 1.0 || d < -1.0)
    domain_error ("asin", arg);
#endif
  IN_FLOAT (d = asin (d), "asin", arg);
  return make_float (d);
}

DEFUN ("atan", Fatan, Satan, 1, 1, 0,
  "Return the inverse tangent of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = atan (d), "atan", arg);
  return make_float (d);
}

DEFUN ("cos", Fcos, Scos, 1, 1, 0,
  "Return the cosine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = cos (d), "cos", arg);
  return make_float (d);
}

DEFUN ("sin", Fsin, Ssin, 1, 1, 0,
  "Return the sine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = sin (d), "sin", arg);
  return make_float (d);
}

DEFUN ("tan", Ftan, Stan, 1, 1, 0,
  "Return the tangent of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  double c = cos (d);
#ifdef FLOAT_CHECK_DOMAIN
  if (c == 0.0)
    domain_error ("tan", arg);
#endif
  IN_FLOAT (d = sin (d) / c, "tan", arg);
  return make_float (d);
}
\f
#if 0 /* Leave these out unless we find there's a reason for them.  */

DEFUN ("bessel-j0", Fbessel_j0, Sbessel_j0, 1, 1, 0,
  "Return the bessel function j0 of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = j0 (d), "bessel-j0", arg);
  return make_float (d);
}

DEFUN ("bessel-j1", Fbessel_j1, Sbessel_j1, 1, 1, 0,
  "Return the bessel function j1 of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = j1 (d), "bessel-j1", arg);
  return make_float (d);
}

DEFUN ("bessel-jn", Fbessel_jn, Sbessel_jn, 2, 2, 0,
  "Return the order N bessel function output jn of ARG.\n\
The first arg (the order) is truncated to an integer.")
  (arg1, arg2)
     register Lisp_Object arg1, arg2;
{
  int i1 = extract_float (arg1);
  double f2 = extract_float (arg2);

  IN_FLOAT (f2 = jn (i1, f2), "bessel-jn", arg1);
  return make_float (f2);
}

DEFUN ("bessel-y0", Fbessel_y0, Sbessel_y0, 1, 1, 0,
  "Return the bessel function y0 of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = y0 (d), "bessel-y0", arg);
  return make_float (d);
}

DEFUN ("bessel-y1", Fbessel_y1, Sbessel_y1, 1, 1, 0,
  "Return the bessel function y1 of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = y1 (d), "bessel-y0", arg);
  return make_float (d);
}

DEFUN ("bessel-yn", Fbessel_yn, Sbessel_yn, 2, 2, 0,
  "Return the order N bessel function output yn of ARG.\n\
The first arg (the order) is truncated to an integer.")
  (arg1, arg2)
     register Lisp_Object arg1, arg2;
{
  int i1 = extract_float (arg1);
  double f2 = extract_float (arg2);

  IN_FLOAT (f2 = yn (i1, f2), "bessel-yn", arg1);
  return make_float (f2);
}

#endif
\f
#if 0 /* Leave these out unless we see they are worth having.  */

DEFUN ("erf", Ferf, Serf, 1, 1, 0,
  "Return the mathematical error function of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = erf (d), "erf", arg);
  return make_float (d);
}

DEFUN ("erfc", Ferfc, Serfc, 1, 1, 0,
  "Return the complementary error function of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = erfc (d), "erfc", arg);
  return make_float (d);
}

DEFUN ("log-gamma", Flog_gamma, Slog_gamma, 1, 1, 0,
  "Return the log gamma of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = lgamma (d), "log-gamma", arg);
  return make_float (d);
}

DEFUN ("cube-root", Fcube_root, Scube_root, 1, 1, 0,
  "Return the cube root of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef HAVE_CBRT
  IN_FLOAT (d = cbrt (d), "cube-root", arg);
#else
  if (d >= 0.0)
    IN_FLOAT (d = pow (d, 1.0/3.0), "cube-root", arg);
  else
    IN_FLOAT (d = -pow (-d, 1.0/3.0), "cube-root", arg);
#endif
  return make_float (d);
}

#endif
\f
DEFUN ("exp", Fexp, Sexp, 1, 1, 0,
  "Return the exponential base e of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d > 709.7827)   /* Assume IEEE doubles here */
    range_error ("exp", arg);
  else if (d < -709.0)
    return make_float (0.0);
  else
#endif
    IN_FLOAT (d = exp (d), "exp", arg);
  return make_float (d);
}

DEFUN ("expt", Fexpt, Sexpt, 2, 2, 0,
  "Return the exponential X ** Y.")
  (arg1, arg2)
     register Lisp_Object arg1, arg2;
{
  double f1, f2;

  CHECK_NUMBER_OR_FLOAT (arg1, 0);
  CHECK_NUMBER_OR_FLOAT (arg2, 0);
  if (XTYPE (arg1) == Lisp_Int     /* common lisp spec */
      && XTYPE (arg2) == Lisp_Int) /* don't promote, if both are ints */
    {				/* this can be improved by pre-calculating */
      int acc, x, y;		/* some binary powers of x then accumulating */
      Lisp_Object val;

      x = XINT (arg1);
      y = XINT (arg2);
      acc = 1;
      
      if (y < 0)
	{
	  if (x == 1)
	    acc = 1;
	  else if (x == -1)
	    acc = (y & 1) ? -1 : 1;
	  else
	    acc = 0;
	}
      else
	{
	  for (; y > 0; y--)
	  while (y > 0)
	    {
	      if (y & 1)
		acc *= x;
	      x *= x;
	      y = (unsigned)y >> 1;
	    }
	}
      XSET (val, Lisp_Int, acc);
      return val;
    }
  f1 = (XTYPE (arg1) == Lisp_Float) ? XFLOAT (arg1)->data : XINT (arg1);
  f2 = (XTYPE (arg2) == Lisp_Float) ? XFLOAT (arg2)->data : XINT (arg2);
  /* Really should check for overflow, too */
  if (f1 == 0.0 && f2 == 0.0)
    f1 = 1.0;
#ifdef FLOAT_CHECK_DOMAIN
  else if ((f1 == 0.0 && f2 < 0.0) || (f1 < 0 && f2 != floor(f2)))
    domain_error2 ("expt", arg1, arg2);
#endif
  IN_FLOAT2 (f1 = pow (f1, f2), "expt", arg1, arg2);
  return make_float (f1);
}

DEFUN ("log", Flog, Slog, 1, 2, 0,
  "Return the natural logarithm of ARG.\n\
If second optional argument BASE is given, return log ARG using that base.")
  (arg, base)
     register Lisp_Object arg, base;
{
  double d = extract_float (arg);

#ifdef FLOAT_CHECK_DOMAIN
  if (d <= 0.0)
    domain_error2 ("log", arg, base);
#endif
  if (NILP (base))
    IN_FLOAT (d = log (d), "log", arg);
  else
    {
      double b = extract_float (base);

#ifdef FLOAT_CHECK_DOMAIN
      if (b <= 0.0 || b == 1.0)
	domain_error2 ("log", arg, base);
#endif
      if (b == 10.0)
	IN_FLOAT2 (d = log10 (d), "log", arg, base);
      else
	IN_FLOAT2 (d = log (d) / log (b), "log", arg, base);
    }
  return make_float (d);
}

DEFUN ("log10", Flog10, Slog10, 1, 1, 0,
  "Return the logarithm base 10 of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d <= 0.0)
    domain_error ("log10", arg);
#endif
  IN_FLOAT (d = log10 (d), "log10", arg);
  return make_float (d);
}

DEFUN ("sqrt", Fsqrt, Ssqrt, 1, 1, 0,
  "Return the square root of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d < 0.0)
    domain_error ("sqrt", arg);
#endif
  IN_FLOAT (d = sqrt (d), "sqrt", arg);
  return make_float (d);
}
\f
#if 0 /* Not clearly worth adding.  */

DEFUN ("acosh", Facosh, Sacosh, 1, 1, 0,
  "Return the inverse hyperbolic cosine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d < 1.0)
    domain_error ("acosh", arg);
#endif
#ifdef HAVE_INVERSE_HYPERBOLIC
  IN_FLOAT (d = acosh (d), "acosh", arg);
#else
  IN_FLOAT (d = log (d + sqrt (d*d - 1.0)), "acosh", arg);
#endif
  return make_float (d);
}

DEFUN ("asinh", Fasinh, Sasinh, 1, 1, 0,
  "Return the inverse hyperbolic sine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef HAVE_INVERSE_HYPERBOLIC
  IN_FLOAT (d = asinh (d), "asinh", arg);
#else
  IN_FLOAT (d = log (d + sqrt (d*d + 1.0)), "asinh", arg);
#endif
  return make_float (d);
}

DEFUN ("atanh", Fatanh, Satanh, 1, 1, 0,
  "Return the inverse hyperbolic tangent of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d >= 1.0 || d <= -1.0)
    domain_error ("atanh", arg);
#endif
#ifdef HAVE_INVERSE_HYPERBOLIC
  IN_FLOAT (d = atanh (d), "atanh", arg);
#else
  IN_FLOAT (d = 0.5 * log ((1.0 + d) / (1.0 - d)), "atanh", arg);
#endif
  return make_float (d);
}

DEFUN ("cosh", Fcosh, Scosh, 1, 1, 0,
  "Return the hyperbolic cosine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d > 710.0 || d < -710.0)
    range_error ("cosh", arg);
#endif
  IN_FLOAT (d = cosh (d), "cosh", arg);
  return make_float (d);
}

DEFUN ("sinh", Fsinh, Ssinh, 1, 1, 0,
  "Return the hyperbolic sine of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
#ifdef FLOAT_CHECK_DOMAIN
  if (d > 710.0 || d < -710.0)
    range_error ("sinh", arg);
#endif
  IN_FLOAT (d = sinh (d), "sinh", arg);
  return make_float (d);
}

DEFUN ("tanh", Ftanh, Stanh, 1, 1, 0,
  "Return the hyperbolic tangent of ARG.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = tanh (d), "tanh", arg);
  return make_float (d);
}
#endif
\f
DEFUN ("abs", Fabs, Sabs, 1, 1, 0,
  "Return the absolute value of ARG.")
  (arg)
     register Lisp_Object arg;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (XTYPE (arg) == Lisp_Float)
    IN_FLOAT (arg = make_float (fabs (XFLOAT (arg)->data)), "abs", arg);
  else if (XINT (arg) < 0)
    XSETINT (arg, - XFASTINT (arg));

  return arg;
}

DEFUN ("float", Ffloat, Sfloat, 1, 1, 0,
  "Return the floating point number equal to ARG.")
  (arg)
     register Lisp_Object arg;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (XTYPE (arg) == Lisp_Int)
    return make_float ((double) XINT (arg));
  else				/* give 'em the same float back */
    return arg;
}

DEFUN ("logb", Flogb, Slogb, 1, 1, 0,
  "Returns largest integer <= the base 2 log of the magnitude of ARG.\n\
This is the same as the exponent of a float.")
     (arg)
     Lisp_Object arg;
{
  Lisp_Object val;
  int value;
  double f = extract_float (arg);

#ifdef HAVE_LOGB
  IN_FLOAT (value = logb (f), "logb", arg);
  XSET (val, Lisp_Int, value);
#else
#ifdef HAVE_FREXP
  {
    int exp;  

    IN_FLOAT (frexp (f, &exp), "logb", arg);
    XSET (val, Lisp_Int, exp-1);
  }
#else
  /* Would someone like to write code to emulate logb?  */
  error ("`logb' not implemented on this operating system");
#endif
#endif

  return val;
}

/* the rounding functions  */

DEFUN ("ceiling", Fceiling, Sceiling, 1, 1, 0,
  "Return the smallest integer no less than ARG.  (Round toward +inf.)")
  (arg)
     register Lisp_Object arg;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (XTYPE (arg) == Lisp_Float)
    IN_FLOAT (XSET (arg, Lisp_Int, ceil (XFLOAT (arg)->data)), "ceiling", arg);

  return arg;
}

#endif /* LISP_FLOAT_TYPE */


DEFUN ("floor", Ffloor, Sfloor, 1, 2, 0,
  "Return the largest integer no greater than ARG.  (Round towards -inf.)\n\
With optional DIVISOR, return the largest integer no greater than ARG/DIVISOR.")
  (arg, divisor)
     register Lisp_Object arg, divisor;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (! NILP (divisor))
    {
      int i1, i2;

      CHECK_NUMBER_OR_FLOAT (divisor, 1);

#ifdef LISP_FLOAT_TYPE
      if (XTYPE (arg) == Lisp_Float || XTYPE (divisor) == Lisp_Float)
	{
	  double f1, f2;

	  f1 = XTYPE (arg) == Lisp_Float ? XFLOAT (arg)->data : XINT (arg);
	  f2 = (XTYPE (divisor) == Lisp_Float
		? XFLOAT (divisor)->data : XINT (divisor));
	  if (f2 == 0)
	    Fsignal (Qarith_error, Qnil);

	  IN_FLOAT2 (XSET (arg, Lisp_Int, floor (f1 / f2)),
		     "floor", arg, divisor);
	  return arg;
	}
#endif

      i1 = XINT (arg);
      i2 = XINT (divisor);

      if (i2 == 0)
	Fsignal (Qarith_error, Qnil);

      /* With C's /, the result is implementation-defined if either operand
	 is negative, so use only nonnegative operands.  */
      i1 = (i2 < 0
	    ? (i1 <= 0  ?  -i1 / -i2  :  -1 - ((i1 - 1) / -i2))
	    : (i1 < 0  ?  -1 - ((-1 - i1) / i2)  :  i1 / i2));

      XSET (arg, Lisp_Int, i1);
      return arg;
    }

#ifdef LISP_FLOAT_TYPE
  if (XTYPE (arg) == Lisp_Float)
    IN_FLOAT (XSET (arg, Lisp_Int, floor (XFLOAT (arg)->data)), "floor", arg);
#endif

  return arg;
}

#ifdef LISP_FLOAT_TYPE

DEFUN ("round", Fround, Sround, 1, 1, 0,
  "Return the nearest integer to ARG.")
  (arg)
     register Lisp_Object arg;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (XTYPE (arg) == Lisp_Float)
    /* Screw the prevailing rounding mode.  */
    IN_FLOAT (XSET (arg, Lisp_Int, rint (XFLOAT (arg)->data)), "round", arg);

  return arg;
}

DEFUN ("truncate", Ftruncate, Struncate, 1, 1, 0,
       "Truncate a floating point number to an int.\n\
Rounds the value toward zero.")
  (arg)
     register Lisp_Object arg;
{
  CHECK_NUMBER_OR_FLOAT (arg, 0);

  if (XTYPE (arg) == Lisp_Float)
    XSET (arg, Lisp_Int, (int) XFLOAT (arg)->data);

  return arg;
}
\f
#if 0
/* It's not clear these are worth adding.  */

DEFUN ("fceiling", Ffceiling, Sfceiling, 1, 1, 0,
  "Return the smallest integer no less than ARG, as a float.\n\
\(Round toward +inf.\)")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = ceil (d), "fceiling", arg);
  return make_float (d);
}

DEFUN ("ffloor", Fffloor, Sffloor, 1, 1, 0,
  "Return the largest integer no greater than ARG, as a float.\n\
\(Round towards -inf.\)")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = floor (d), "ffloor", arg);
  return make_float (d);
}

DEFUN ("fround", Ffround, Sfround, 1, 1, 0,
  "Return the nearest integer to ARG, as a float.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  IN_FLOAT (d = rint (XFLOAT (arg)->data), "fround", arg);
  return make_float (d);
}

DEFUN ("ftruncate", Fftruncate, Sftruncate, 1, 1, 0,
       "Truncate a floating point number to an integral float value.\n\
Rounds the value toward zero.")
  (arg)
     register Lisp_Object arg;
{
  double d = extract_float (arg);
  if (d >= 0.0)
    IN_FLOAT (d = floor (d), "ftruncate", arg);
  else
    IN_FLOAT (d = ceil (d), "ftruncate", arg);
  return make_float (d);
}
#endif
\f
#ifdef FLOAT_CATCH_SIGILL
static SIGTYPE
float_error (signo)
     int signo;
{
  if (! in_float)
    fatal_error_signal (signo);

#ifdef BSD
#ifdef BSD4_1
  sigrelse (SIGILL);
#else /* not BSD4_1 */
  sigsetmask (SIGEMPTYMASK);
#endif /* not BSD4_1 */
#else
  /* Must reestablish handler each time it is called.  */
  signal (SIGILL, float_error);
#endif /* BSD */

  in_float = 0;

  Fsignal (Qarith_error, Fcons (float_error_arg, Qnil));
}

/* Another idea was to replace the library function `infnan'
   where SIGILL is signaled.  */

#endif /* FLOAT_CATCH_SIGILL */

#ifdef HAVE_MATHERR
int 
matherr (x)
     struct exception *x;
{
  Lisp_Object args;
  if (! in_float)
    /* Not called from emacs-lisp float routines; do the default thing. */
    return 0;
  if (!strcmp (x->name, "pow"))
    x->name = "expt";

  args
    = Fcons (build_string (x->name),
	     Fcons (make_float (x->arg1),
		    ((!strcmp (x->name, "log") || !strcmp (x->name, "pow"))
		     ? Fcons (make_float (x->arg2), Qnil)
		     : Qnil)));
  switch (x->type)
    {
    case DOMAIN:	Fsignal (Qdomain_error, args);		break;
    case SING:		Fsignal (Qsingularity_error, args);	break;
    case OVERFLOW:	Fsignal (Qoverflow_error, args);	break;
    case UNDERFLOW:	Fsignal (Qunderflow_error, args);	break;
    default:		Fsignal (Qarith_error, args);		break;
    }
  return (1);	/* don't set errno or print a message */
}
#endif /* HAVE_MATHERR */

init_floatfns ()
{
#ifdef FLOAT_CATCH_SIGILL
  signal (SIGILL, float_error);
#endif 
  in_float = 0;
}

#else /* not LISP_FLOAT_TYPE */

init_floatfns ()
{}

#endif /* not LISP_FLOAT_TYPE */

syms_of_floatfns ()
{
#ifdef LISP_FLOAT_TYPE
  defsubr (&Sacos);
  defsubr (&Sasin);
  defsubr (&Satan);
  defsubr (&Scos);
  defsubr (&Ssin);
  defsubr (&Stan);
#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);
  defsubr (&Sfceiling);
  defsubr (&Sffloor);
  defsubr (&Sfround);
  defsubr (&Sftruncate);
#endif
  defsubr (&Sexp);
  defsubr (&Sexpt);
  defsubr (&Slog);
  defsubr (&Slog10);
  defsubr (&Ssqrt);

  defsubr (&Sabs);
  defsubr (&Sfloat);
  defsubr (&Slogb);
  defsubr (&Sceiling);
  defsubr (&Sround);
  defsubr (&Struncate);
#endif /* LISP_FLOAT_TYPE */
  defsubr (&Sfloor);
}