src/sage/functions/min_max.py: consolidate "needs sage.symbolic" tags

As the name suggests, this whole file needs sage.symbolic. There are
one or two lines that might run without it, but no meaningful tests
can be done, so let's require it at the file level and clean up.

Author: orlitzky

src/sage/functions/min_max.py

@@ -1,3 +1,4 @@
+# sage.doctest: needs sage.symbolic
 r"""
 Symbolic minimum and maximum
 
@@ -7,16 +8,15 @@
 
 Here you can see some differences::
 
-   sage: max(x, x^2)                                                                    # needs sage.symbolic
+   sage: max(x, x^2)
    x
-   sage: max_symbolic(x, x^2)                                                           # needs sage.symbolic
+   sage: max_symbolic(x, x^2)
    max(x, x^2)
-   sage: f(x) = max_symbolic(x, x^2); f(1/2)                                            # needs sage.symbolic
+   sage: f(x) = max_symbolic(x, x^2); f(1/2)
    1/2
 
 This works as expected for more than two entries::
 
-   sage: # needs sage.symbolic
    sage: max(3, 5, x)
    5
    sage: min(3, 5, x)
@@ -48,7 +48,6 @@ def eval_helper(self, this_f, builtin_f, initial_val, args):
         """
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: max_symbolic(3, 5, x)  # indirect doctest
             max(x, 5)
             sage: max_symbolic([5.0r])   # indirect doctest
@@ -93,20 +92,20 @@ def __call__(self, *args, **kwds):
         """
         EXAMPLES::
 
-            sage: max_symbolic(3, 5, x)                                                 # needs sage.symbolic
+            sage: max_symbolic(3, 5, x)
             max(x, 5)
-            sage: max_symbolic(3, 5, x, hold=True)                                      # needs sage.symbolic
+            sage: max_symbolic(3, 5, x, hold=True)
             max(3, 5, x)
-            sage: max_symbolic([3, 5, x])                                               # needs sage.symbolic
+            sage: max_symbolic([3, 5, x])
             max(x, 5)
 
         ::
 
-            sage: min_symbolic(3, 5, x)                                                 # needs sage.symbolic
+            sage: min_symbolic(3, 5, x)
             min(x, 3)
-            sage: min_symbolic(3, 5, x, hold=True)                                      # needs sage.symbolic
+            sage: min_symbolic(3, 5, x, hold=True)
             min(3, 5, x)
-            sage: min_symbolic([3, 5, x])                                               # needs sage.symbolic
+            sage: min_symbolic([3, 5, x])
             min(x, 3)
 
         TESTS:
@@ -120,7 +119,6 @@ def __call__(self, *args, **kwds):
 
         Check if a single argument which is not iterable works::
 
-            sage: # needs sage.symbolic
             sage: max_symbolic(None)
             Traceback (most recent call last):
             ...
@@ -161,13 +159,13 @@ def __init__(self):
         r"""
         Symbolic `\max` function.
 
-        The Python builtin :func:`max` function does not work as expected when symbolic
-        expressions are given as arguments. This function delays evaluation
-        until all symbolic arguments are substituted with values.
+        The Python builtin :func:`max` function does not work as
+        expected when symbolic expressions are given as
+        arguments. This function delays evaluation until all symbolic
+        arguments are substituted with values.
 
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: max_symbolic(3, x)
             max(3, x)
             sage: max_symbolic(3, x).subs(x=5)
@@ -179,11 +177,11 @@ def __init__(self):
 
         TESTS::
 
-            sage: loads(dumps(max_symbolic(x, 5)))                                      # needs sage.symbolic
+            sage: loads(dumps(max_symbolic(x, 5)))
             max(x, 5)
-            sage: latex(max_symbolic(x, 5))                                             # needs sage.symbolic
+            sage: latex(max_symbolic(x, 5))
             \max\left(x, 5\right)
-            sage: max_symbolic(x, 5)._sympy_()                                          # needs sympy sage.symbolic
+            sage: max_symbolic(x, 5)._sympy_()  # needs sympy
             Max(5, x)
         """
         BuiltinFunction.__init__(self, 'max', nargs=0, latex_name=r"\max",
@@ -193,7 +191,6 @@ def _eval_(self, *args):
         """
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: t = max_symbolic(x, 5); t
             max(x, 5)
             sage: t.subs(x=3)  # indirect doctest
@@ -222,7 +219,6 @@ def _evalf_(self, *args, **kwds):
         """
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: t = max_symbolic(sin(x), cos(x))
             sage: t.subs(x=1).n(200)
             0.84147098480789650665250232163029899962256306079837106567275
@@ -239,7 +235,7 @@ def _evalf_(self, *args, **kwds):
         We can usually integrate these expressions, but can't
         guarantee a symbolic answer in closed form::
 
-            sage: # long time, needs sage.symbolic
+            sage: # long time
             sage: f = max_symbolic(sin(x), cos(x))
             sage: r = integral(f, x, 0, 1)
             ...
@@ -263,7 +259,6 @@ def __init__(self):
 
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: min_symbolic(3, x)
             min(3, x)
             sage: min_symbolic(3, x).subs(x=5)
@@ -275,11 +270,11 @@ def __init__(self):
 
         TESTS::
 
-            sage: loads(dumps(min_symbolic(x, 5)))                                      # needs sage.symbolic
+            sage: loads(dumps(min_symbolic(x, 5)))
             min(x, 5)
-            sage: latex(min_symbolic(x, 5))                                             # needs sage.symbolic
+            sage: latex(min_symbolic(x, 5))
             \min\left(x, 5\right)
-            sage: min_symbolic(x, 5)._sympy_()                                          # needs sympy sage.symbolic
+            sage: min_symbolic(x, 5)._sympy_()  # needs sympy
             Min(5, x)
         """
         BuiltinFunction.__init__(self, 'min', nargs=0, latex_name=r"\min",
@@ -289,7 +284,6 @@ def _eval_(self, *args):
         """
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: t = min_symbolic(x, 5); t
             min(x, 5)
             sage: t.subs(x=3)  # indirect doctest
@@ -318,7 +312,6 @@ def _evalf_(self, *args, **kwds):
         """
         EXAMPLES::
 
-            sage: # needs sage.symbolic
             sage: t = min_symbolic(sin(x), cos(x))
             sage: t.subs(x=1).n(200)
             0.54030230586813971740093660744297660373231042061792222767010