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Add configure-time test for log1p disrespecting zero sign.

This commit is contained in:
Mark Dickinson 2010-11-20 10:09:56 +00:00
parent 22170edaf5
commit 7edecdd222
1 changed files with 32 additions and 3 deletions
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35
configure.in
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@ -3372,6 +3372,10 @@ fi
LIBS_SAVE=$LIBS
LIBS="$LIBS $LIBM"
AC_CHECK_FUNCS([acosh asinh atanh copysign erf erfc expm1 finite gamma])
AC_CHECK_FUNCS([hypot lgamma log1p round tgamma])
AC_CHECK_DECLS([isinf, isnan, isfinite], [], [], [[#include <math.h>]])
# On FreeBSD 6.2, it appears that tanh(-0.) returns 0. instead of
# -0. on some architectures.
AC_MSG_CHECKING(whether tanh preserves the sign of zero)
@ -3398,9 +3402,34 @@ then
[Define if tanh(-0.) is -0., or if platform doesn't have signed zeros])
fi
AC_CHECK_FUNCS([acosh asinh atanh copysign erf erfc expm1 finite gamma])
AC_CHECK_FUNCS([hypot lgamma log1p round tgamma])
AC_CHECK_DECLS([isinf, isnan, isfinite], [], [], [[#include <math.h>]])
if test "$ac_cv_func_log1p" = yes
then
# On some versions of AIX, log1p(-0.) returns 0. instead of
# -0. See issue #9920.
AC_MSG_CHECKING(whether log1p drops the sign of negative zero)
AC_CACHE_VAL(ac_cv_log1p_drops_zero_sign, [
AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <math.h>
#include <stdlib.h>
int main() {
/* Fail if the signs of log1p(-0.) and -0. can be
distinguished. */
if (atan2(log1p(-0.), -1.) == atan2(-0., -1.))
return 0;
else
return 1;
}
]])],
[ac_cv_log1p_drops_zero_sign=no],
[ac_cv_log1p_drops_zero_sign=yes],
[ac_cv_log1p_drops_zero_sign=no])])
AC_MSG_RESULT($ac_cv_log1p_drops_zero_sign)
fi
if test "$ac_cv_log1p_drops_zero_sign" = yes
then
AC_DEFINE(LOG1P_DROPS_ZERO_SIGN, 1,
[Define if log1p(-0.) is 0. rather than -0.])
fi
LIBS=$LIBS_SAVE