--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2012-02-29  Bruno Haible  <bruno@clisp.org>
+
+	hypot tests: More tests.
+	* tests/test-hypot.c: Include <float.h>.
+	(main): Add tests about overflow and underflow.
+
 2012-02-29  Bruno Haible  <bruno@clisp.org>
 
 	math code: Add comments.

--- a/tests/test-hypot.c
+++ b/tests/test-hypot.c
@@ -23,6 +23,8 @@
 #include "signature.h"
 SIGNATURE_CHECK (hypot, double, (double, double));
 
+#include <float.h>
+
 #include "macros.h"
 
 volatile double x;
@@ -38,5 +40,23 @@
   z = hypot (x, y);
   ASSERT (z >= 0.7211102550 && z <= 0.7211102551);
 
+  /* Overflow.  */
+  x = DBL_MAX;
+  y = DBL_MAX * 0.5;
+  z = hypot (x, y);
+  ASSERT (z == HUGE_VAL);
+
+  /* No underflow.  */
+  x = DBL_MIN;
+  y = 0.0;
+  z = hypot (x, y);
+  ASSERT (z == DBL_MIN);
+
+  /* No underflow.  */
+  x = DBL_MIN * 2.0;
+  y = DBL_MIN * 3.0;
+  z = hypot (x, y);
+  ASSERT (z >= DBL_MIN * 2.0 && z <= DBL_MIN * 4.0);
+
   return 0;
 }