Add a PoorScalingException for the "math domain errors" that haunt me.

[dunshire.git] / dunshire / games.py

diff --git a/dunshire/games.py b/dunshire/games.py
index 80f5f8ae2a46d09f15e34546c511edeca286f4fa..9610802e4ffd4108d2c244b2c36a9e44084427cd 100644 (file)
--- a/dunshire/games.py
+++ b/dunshire/games.py
@@ -7,7 +7,7 @@ knows how to solve a linear game.
 
 from cvxopt import matrix, printing, solvers
 from .cones import CartesianProduct
 
 from cvxopt import matrix, printing, solvers
 from .cones import CartesianProduct

-from .errors import GameUnsolvableException
+from .errors import GameUnsolvableException, PoorScalingException

 from .matrices import append_col, append_row, identity
 from . import options
 
 from .matrices import append_col, append_row, identity
 from . import options
 


@@ -351,6 +351,10 @@ class SymmetricLinearGame:
             If the game could not be solved (if an optimal solution to its
             associated cone program was not found).
 
             If the game could not be solved (if an optimal solution to its
             associated cone program was not found).
 

+        PoorScalingException
+            If the game could not be solved because CVXOPT crashed while
+            trying to take the square root of a negative number.
+

         Examples
         --------
 
         Examples
         --------
 


@@ -425,7 +429,16 @@ class SymmetricLinearGame:
 
         # Actually solve the thing and obtain a dictionary describing
         # what happened.
 
         # Actually solve the thing and obtain a dictionary describing
         # what happened.

-        soln_dict = solvers.conelp(c, G, h, C.cvxopt_dims(), A, b)
+        try:
+            soln_dict = solvers.conelp(c, G, h, C.cvxopt_dims(), A, b)
+        except ValueError as e:
+            if str(e) == 'math domain error':
+                # Oops, CVXOPT tried to take the square root of a
+                # negative number. Report some details about the game
+                # rather than just the underlying CVXOPT crash.
+                raise PoorScalingException(self)
+            else:
+                raise e

 
         # The optimal strategies are named ``p`` and ``q`` in the
         # background documentation, and we need to extract them from
 
         # The optimal strategies are named ``p`` and ``q`` in the
         # background documentation, and we need to extract them from