Typo fix

Author: tohtsky

pymc3/distributions/discrete.py

@@ -1697,7 +1697,7 @@ class OrderedProbit(Categorical):
                             2*np.ones(n2_c),
                             3*np.ones(n3_c))) - 1
 
-        # Ordered logistic regression
+        # Ordered probit regression
         with pm.Model() as model:
             cutpoints = pm.Normal("cutpoints", mu=[-1,1], sigma=10, shape=2,
                                   transform=pm.distributions.transforms.ordered)

pymc3/distributions/dist_math.py

@@ -160,7 +160,7 @@ def log_diff_normal_cdf(mu, sigma, x, y):
 
     # To stabilize the computation, consider these three regions:
     # 1) x > y > 0 => Use erf(x) = 1 - e^{-x^2} erfcx(x) and erf(y) =1 - e^{-y^2} erfcx(y)
-    # 2) 0 > x > 0 => Use erf(x) = e^{-x^2} erfcx(-x) and erf(y) = e^{-y^2} erfcx(-y)
+    # 2) 0 > x > y => Use erf(x) = e^{-x^2} erfcx(-x) and erf(y) = e^{-y^2} erfcx(-y)
     # 3) x > 0 > y => Naive formula log( (erf(x) - erf(y)) / 2 ) works fine.
     return tt.log(0.5) + tt.switch(
         tt.gt(y, 0),