+
+dnl Test whether sqrtl() works.
+dnl On OpenBSD 5.1/SPARC, sqrtl(8.1974099812331540680810141969554806865L) has
+dnl rounding errors that eat up the last 8 to 9 decimal digits.
+AC_DEFUN([gl_FUNC_SQRTL_WORKS],
+[
+ AC_REQUIRE([AC_PROG_CC])
+ AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+ AC_CACHE_CHECK([whether sqrtl works], [gl_cv_func_sqrtl_works],
+ [
+ AC_RUN_IFELSE(
+ [AC_LANG_SOURCE([[
+#include <float.h>
+#include <math.h>
+#ifndef sqrtl /* for AIX */
+extern
+#ifdef __cplusplus
+"C"
+#endif
+long double sqrtl (long double);
+#endif
+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;
+long double z;
+int main ()
+{
+ x = 8.1974099812331540680810141969554806865L;
+ y = sqrtl (x);
+ z = y * y - x;
+ z = my_ldexpl (z, LDBL_MANT_DIG);
+ if (z < 0)
+ z = - z;
+ if (z > 100.0L)
+ return 1;
+ return 0;
+}
+]])],
+ [gl_cv_func_sqrtl_works=yes],
+ [gl_cv_func_sqrtl_works=no],
+ [case "$host_os" in
+ openbsd*) gl_cv_func_sqrtl_works="guessing no";;
+ *) gl_cv_func_sqrtl_works="guessing yes";;
+ esac
+ ])
+ ])
+])