+
+ m4_ifdef([gl_FUNC_HYPOT_IEEE], [
+ if test $gl_hypot_required = ieee && test $REPLACE_HYPOT = 0; then
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_CACHE_CHECK([whether hypot works according to ISO C 99 with IEC 60559],
+ [gl_cv_func_hypot_ieee],
+ [
+ save_LIBS="$LIBS"
+ LIBS="$LIBS $HYPOT_LIBM"
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#ifndef __NO_MATH_INLINES
+# define __NO_MATH_INLINES 1 /* for glibc */
+#endif
+#include <math.h>
+/* Compare two numbers with ==.
+ This is a separate function because IRIX 6.5 "cc -O" miscompiles an
+ 'x == x' test. */
+static int
+numeric_equal (double x, double y)
+{
+ return x == y;
+}
+static double dummy (double x, double y) { return 0; }
+double zero;
+double one = 1.0;
+int main (int argc, char *argv[])
+{
+ double (*my_hypot) (double, double) = argc ? hypot : dummy;
+ double f;
+ /* Test hypot(NaN,Infinity).
+ This test fails on OSF/1 5.1 and native Windows. */
+ f = my_hypot (zero / zero, one / zero);
+ if (!numeric_equal (f, f))
+ return 1;
+ return 0;
+}
+ ]])],
+ [gl_cv_func_hypot_ieee=yes],
+ [gl_cv_func_hypot_ieee=no],
+ [case "$host_os" in
+ # Guess yes on glibc systems.
+ *-gnu*) gl_cv_func_hypot_ieee="guessing yes" ;;
+ # If we don't know, assume the worst.
+ *) gl_cv_func_hypot_ieee="guessing no" ;;
+ esac
+ ])
+ LIBS="$save_LIBS"
+ ])
+ case "$gl_cv_func_hypot_ieee" in
+ *yes) ;;
+ *) REPLACE_HYPOT=1 ;;
+ esac
+ fi
+ ])
+ if test $REPLACE_HYPOT = 1; then
+ dnl Find libraries needed to link lib/hypot.c.
+ AC_REQUIRE([gl_FUNC_FABS])
+ AC_REQUIRE([gl_FUNC_FREXP])
+ AC_REQUIRE([gl_FUNC_LDEXP])
+ AC_REQUIRE([gl_FUNC_SQRT])
+ HYPOT_LIBM=
+ dnl Append $FABS_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+ case " $HYPOT_LIBM " in
+ *" $FABS_LIBM "*) ;;
+ *) HYPOT_LIBM="$HYPOT_LIBM $FABS_LIBM" ;;
+ esac
+ dnl Append $FREXP_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+ case " $HYPOT_LIBM " in
+ *" $FREXP_LIBM "*) ;;
+ *) HYPOT_LIBM="$HYPOT_LIBM $FREXP_LIBM" ;;
+ esac
+ dnl Append $LDEXP_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+ case " $HYPOT_LIBM " in
+ *" $LDEXP_LIBM "*) ;;
+ *) HYPOT_LIBM="$HYPOT_LIBM $LDEXP_LIBM" ;;
+ esac
+ dnl Append $SQRT_LIBM to HYPOT_LIBM, avoiding gratuitous duplicates.
+ case " $HYPOT_LIBM " in
+ *" $SQRT_LIBM "*) ;;
+ *) HYPOT_LIBM="$HYPOT_LIBM $SQRT_LIBM" ;;
+ esac
+ fi