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# log.m4 serial 4
dnl Copyright (C) 2011-2017 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
AC_DEFUN([gl_FUNC_LOG],
[
m4_divert_text([DEFAULTS], [gl_log_required=plain])
AC_REQUIRE([gl_MATH_H_DEFAULTS])
dnl Determine LOG_LIBM.
gl_COMMON_DOUBLE_MATHFUNC([log])
save_LIBS="$LIBS"
LIBS="$LIBS $LOG_LIBM"
gl_FUNC_LOG_WORKS
LIBS="$save_LIBS"
case "$gl_cv_func_log_works" in
*yes) ;;
*) REPLACE_LOG=1 ;;
esac
m4_ifdef([gl_FUNC_LOG_IEEE], [
if test $gl_log_required = ieee && test $REPLACE_LOG = 0; then
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether log works according to ISO C 99 with IEC 60559],
[gl_cv_func_log_ieee],
[
save_LIBS="$LIBS"
LIBS="$LIBS $LOG_LIBM"
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#ifndef __NO_MATH_INLINES
# define __NO_MATH_INLINES 1 /* for glibc */
#endif
#include <math.h>
/* Compare two numbers with ==.
This is a separate function because IRIX 6.5 "cc -O" miscompiles an
'x == x' test. */
static int
numeric_equal (double x, double y)
{
return x == y;
}
static double dummy (double x) { return 0; }
int main (int argc, char *argv[])
{
double (*my_log) (double) = argc ? log : dummy;
/* Test log(negative).
This test fails on NetBSD 5.1, Solaris 11 2011-11. */
double y = my_log (-1.0);
if (numeric_equal (y, y))
return 1;
return 0;
}
]])],
[gl_cv_func_log_ieee=yes],
[gl_cv_func_log_ieee=no],
[case "$host_os" in
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_log_ieee="guessing yes" ;;
# If we don't know, assume the worst.
*) gl_cv_func_log_ieee="guessing no" ;;
esac
])
LIBS="$save_LIBS"
])
case "$gl_cv_func_log_ieee" in
*yes) ;;
*) REPLACE_LOG=1 ;;
esac
fi
])
])
dnl Test whether log() works.
dnl On OSF/1 5.1, log(-0.0) is NaN.
AC_DEFUN([gl_FUNC_LOG_WORKS],
[
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
AC_CACHE_CHECK([whether log works], [gl_cv_func_log_works],
[
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <math.h>
volatile double x;
double y;
int main ()
{
x = -0.0;
y = log (x);
if (!(y + y == y))
return 1;
return 0;
}
]])],
[gl_cv_func_log_works=yes],
[gl_cv_func_log_works=no],
[case "$host_os" in
osf*) gl_cv_func_log_works="guessing no";;
*) gl_cv_func_log_works="guessing yes";;
esac
])
])
])
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