Repository: scipy/scipy
Pull request: DOC: Change mielke distribution default parameters to ensure kurtosis exists.
The kurtosis calculation for mielke distribution (parameters `k` & `s`) does
not converge if `s` is too small.  (See gh-9833)  Change the default parameters for testing from `(10.4, 3.6)` to `(10.4, 4.6)`. (Any value of `s` bigger than `4` should be sufficient to ensure mathematical convergence. `4.6` is big enough that there are no computational convergence problems either.) 
This removes a warning during building of the doc, which calls `mielke.stats(k, s, moments='mvsk')`

Also added a reference for the distribution.

Closes gh-9833.


Problem statement:
IntegrationWarning from mielke.stats() during build of html doc.
An IntegrationWarning occurs while building the docs.

### Reproducing code example:
```
$ pushed doc && make clean &&  make html
```

### Error message:
```
.../scipy/scipy/stats/_distn_infrastructure.py:1613: IntegrationWarning: The integral is probably divergent, or slowly convergent.                                                      
  return integrate.quad(self._mom_integ1, 0, 1, args=(m,)+args)[0]
```

After some digging, the culprit is the `mielke` distribution.  The doc creation calls
```
mean, var, skew, kurt = mielke.stats(k, s, moments='mvsk')
```

The `mielke`'s default parameters are `(k, s)= (10.4, 3.6)`.  The kurtosis calculation does not converge if `s <= 4`, and a warning is generated.

### Scipy/Numpy/Python version information:
```
1.3.0.dev0+12175d2 1.16.0 sys.version_info(major=3, minor=6, micro=6, releaselevel='final', serial=0)
```

Hints from issue discussion:

Commit message: DOC: Indent a line in the References section of mielke.

Patch to review:
diff --git a/scipy/stats/_continuous_distns.py b/scipy/stats/_continuous_distns.py
index e30a2ff18078..866c8f927094 100644
--- a/scipy/stats/_continuous_distns.py
+++ b/scipy/stats/_continuous_distns.py
@@ -4583,7 +4583,7 @@ def _entropy(self):
 
 
 class mielke_gen(rv_continuous):
-    r"""A Mielke's Beta-Kappa continuous random variable.
+    r"""Mielke's Beta-Kappa continuous random variable[1]_.
 
     %(before_notes)s
 
@@ -4601,6 +4601,11 @@ class mielke_gen(rv_continuous):
 
     %(after_notes)s
 
+    References
+    ----------
+    .. [1] Mielke, P.W., 1973 "Another Family of Distributions for Describing
+           and Analyzing Precipitation Data." J. Appl. Meteor., 12, 275-280
+
     %(example)s
 
     """
diff --git a/scipy/stats/_distr_params.py b/scipy/stats/_distr_params.py
index 2018c9bde1c4..52976ecdc776 100644
--- a/scipy/stats/_distr_params.py
+++ b/scipy/stats/_distr_params.py
@@ -73,7 +73,7 @@
     ['lognorm', (0.95368226960575331,)],
     ['lomax', (1.8771398388773268,)],
     ['maxwell', ()],
-    ['mielke', (10.4, 3.6)],
+    ['mielke', (10.4, 4.6)],
     ['moyal', ()],
     ['nakagami', (4.9673794866666237,)],
     ['ncf', (27, 27, 0.41578441799226107)],


Code review comments:
diff_hunk: @@ -4583,7 +4583,7 @@ def _entropy(self):
 
 
 class mielke_gen(rv_continuous):
-    r"""A Mielke's Beta-Kappa continuous random variable.
+    r"""Mielke's Beta-Kappa continuous random variable[1]_.
path: scipy/stats/_continuous_distns.py
text: @user1:
this text shows up in the overview here: https://docs.scipy.org/doc/scipy/reference/stats.html

Better put the reference to the notes