Applied Anand's patch fixing Ticket #986 regarding the domain of the Von Mises random variable generator. Regression test added.

2 files changed, 22 insertions, 3 deletions

diff --git a/numpy/random/mtrand/distributions.c b/numpy/random/mtrand/distributions.c
index 8cd508f7a..08a0d49f1 100644
--- a/numpy/random/mtrand/distributions.c
+++ b/numpy/random/mtrand/distributions.c
@@ -561,6 +561,7 @@ double rk_vonmises(rk_state *state, double mu, double kappa)
     double r, rho, s;
     double U, V, W, Y, Z;
     double result, mod;
+    int neg;
 
     if (kappa < 1e-8)
     {
@@ -585,15 +586,22 @@ double rk_vonmises(rk_state *state, double mu, double kappa)
             }
         }
 
-	U = rk_double(state);
+        U = rk_double(state);
 
-	result = acos(W);
+        result = acos(W);
         if (U < 0.5)
         {
 	    result = -result;
         }
         result += mu;
-        mod = fmod(result, 2*M_PI);
+        neg = (result < 0);
+        mod = fabs(result);
+        mod = (fmod(mod+M_PI, 2*M_PI)-M_PI);
+        if (neg)
+        {
+            mod *= -1;
+        }         
+
         return mod;
     }
 }
diff --git a/numpy/random/tests/test_random.py b/numpy/random/tests/test_random.py
index 8dae16fcb..9d3de27e2 100644
--- a/numpy/random/tests/test_random.py
+++ b/numpy/random/tests/test_random.py
@@ -15,6 +15,17 @@ class TestMultinomial(TestCase):
         assert np.all(-5 <= x)
         assert np.all(x < -1)
 
+class TestVonMises(TestCase):
+    def test_output_domain(self):
+        """Make sure generated random variables are in [-pi, pi].
+
+        Regression test for ticket #986.
+        """
+        for mu in np.linspace(-7., 7., 5):        
+            r = random.mtrand.vonmises(mu,1,50)
+            assert np.all(r>-np.pi) and np.all(r<=np.pi)
+
+
 
 class TestSetState(TestCase):
     def setUp(self):