Added _sf function again to argus distribution and added unittests

yxdragon · Nov 19, 2016 · b851f3f · b851f3f
1 parent 49596bb
commit b851f3f
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/scipy/stats/_continuous_distns.py b/scipy/stats/_continuous_distns.py
@@ -5253,7 +5253,13 @@ def _cdf(self, x, chi):
         """
         Return CDF of the argus function
         """
-        return 1.0 - _argus_phi(chi * np.sqrt(1 - x**2)) / _argus_phi(chi)
+        return 1.0 - self._sf(x, chi)
+
+    def _sf(self, x, chi):
+        """
+        Return survival function of the argus function
+        """
+        return _argus_phi(chi * np.sqrt(1 - x**2)) / _argus_phi(chi)
 argus = argus_gen(name='argus', longname="An Argus Function", a=0.0, b=1.0)
 
 

diff --git a/scipy/stats/tests/test_distributions.py b/scipy/stats/tests/test_distributions.py
@@ -3021,6 +3021,7 @@ def test_argus_function():
 
     for i in range(1, 10):
         assert_equal(stats.argus.cdf(1.0, chi=i), 1.0)
+        assert_equal(stats.argus.cdf(1.0, chi=i), 1.0 - stats.argus.sf(1.0, chi=i))
 
 
 if __name__ == "__main__":