making PPL default solver + doctest added

sagemath · Aug 20, 2017 · 66322e3 · 66322e3
1 parent effcedb
commit 66322e3
Showing 1 changed file with 11 additions and 4 deletions.
diff --git a/src/sage/graphs/graph.py b/src/sage/graphs/graph.py
@@ -4679,7 +4679,7 @@ def has_homomorphism_to(self, H, core = False, solver = None, verbose = 0):
             return False
 
     @doc_index("Leftovers")
-    def fractional_chromatic_index(self, solver = None, verbose_constraints = 0, verbose = 0):
+    def fractional_chromatic_index(self, solver = "PPL", verbose_constraints = 0, verbose = 0):
         r"""
         Computes the fractional chromatic index of ``self``
 
@@ -4744,12 +4744,19 @@ def fractional_chromatic_index(self, solver = None, verbose_constraints = 0, ver
 
             sage: g = graphs.CycleGraph(5)
             sage: g.fractional_chromatic_index()
+            5/2
+
+        With GLPK::
+
+            sage: g.fractional_chromatic_index(solver="GLPK")
             2.5
 
-        With PPL::
+        Check that :trac:`23658` is fixed::
+
+            sage: g=graphs.PetersenGraph()
+            sage: g.fractional_chromatic_index()
+            3
 
-            sage: g.fractional_chromatic_index(solver="PPL")
-            5/2
         """
         self._scream_if_not_simple()
         from sage.numerical.mip import MixedIntegerLinearProgram