-# hypotl.m4 serial 3
+# hypotl.m4 serial 4
dnl Copyright (C) 2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
LIBS="$save_LIBS"
if test $ac_cv_func_hypotl = yes; then
HYPOTL_LIBM="$HYPOT_LIBM"
+
+ save_LIBS="$LIBS"
+ LIBS="$LIBS $HYPOTL_LIBM"
+ gl_FUNC_HYPOTL_WORKS
+ LIBS="$save_LIBS"
+ case "$gl_cv_func_hypotl_works" in
+ *yes) ;;
+ *) REPLACE_HYPOTL=1 ;;
+ esac
+
m4_ifdef([gl_FUNC_HYPOTL_IEEE], [
if test $gl_hypotl_required = ieee && test $REPLACE_HYPOTL = 0; then
AC_CACHE_CHECK([whether hypotl works according to ISO C 99 with IEC 60559],
fi
AC_SUBST([HYPOTL_LIBM])
])
+
+dnl Test whether hypotl() works.
+dnl On OpenBSD 5.1/SPARC,
+dnl hypotl (2.5541394760659556563446062497337725156L, 7.7893454113437840832487794525518765265L)
+dnl has rounding errors that eat up the last 8 to 9 decimal digits.
+AC_DEFUN([gl_FUNC_HYPOTL_WORKS],
+[
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_CACHE_CHECK([whether hypotl works], [gl_cv_func_hypotl_works],
+ [
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#include <float.h>
+#include <math.h>
+static long double
+my_ldexpl (long double x, int d)
+{
+ for (; d > 0; d--)
+ x *= 2.0L;
+ for (; d < 0; d++)
+ x *= 0.5L;
+ return x;
+}
+volatile long double x;
+volatile long double y;
+volatile long double z;
+int main ()
+{
+ long double err;
+
+ x = 2.5541394760659556563446062497337725156L;
+ y = 7.7893454113437840832487794525518765265L;
+ z = hypotl (x, y);
+ err = z * z - (x * x + y * y);
+ err = my_ldexpl (err, LDBL_MANT_DIG);
+ if (err < 0)
+ err = - err;
+ if (err > 1000.0L)
+ return 1;
+ return 0;
+}
+]])],
+ [gl_cv_func_hypotl_works=yes],
+ [gl_cv_func_hypotl_works=no],
+ [case "$host_os" in
+ openbsd*) gl_cv_func_hypotl_works="guessing no";;
+ *) gl_cv_func_hypotl_works="guessing yes";;
+ esac
+ ])
+ ])
+])