fix #1441

gpkit/nomials/math.py

@@ -394,14 +394,18 @@ def __init__(self, left, oper, right):
     def relaxed(self, relaxvar):
         "Returns the relaxation of the constraint in a list."
         if self.oper == ">=":
-            return [relaxvar*self.left >= self.right]
+            relaxed = [relaxvar*self.left >= self.right]
         elif self.oper == "<=":
-            return [self.left <= relaxvar*self.right]
+            relaxed = [self.left <= relaxvar*self.right]
         elif self.oper == "=":
-            return [self.left <= relaxvar*self.right,
-                    relaxvar*self.left >= self.right]
-        raise ValueError(
-            "Constraint %s had unknown operator %s." % self.oper, self)
+            relaxed = [self.left <= relaxvar*self.right,
+                       relaxvar*self.left >= self.right]
+        else:
+            raise ValueError(
+                "Constraint %s had unknown operator %s." % self.oper, self)
+        for constr in relaxed:
+            constr.sgp_parent = self
+        return relaxed
 
 
 # pylint: disable=too-many-instance-attributes, invalid-unary-operand-type
@@ -519,6 +523,8 @@ def sens_from_dual(self, la, nu, result):  # pylint: disable=unused-argument
         self.relax_sensitivity = la
         if self.sgp_parent:
             self.sgp_parent.relax_sensitivity = la
+            if getattr(self.sgp_parent, "sgp_parent", None):
+                self.sgp_parent.sgp_parent.relax_sensitivity = la
         nu, = nu
         presub, = self.unsubbed
         if hasattr(self, "pmap"):
@@ -600,6 +606,8 @@ def sens_from_dual(self, la, nu, result):
         self.relax_sensitivity = la[0] - la[1]
         if self.sgp_parent:
             self.sgp_parent.relax_sensitivity = self.relax_sensitivity
+            if getattr(self.sgp_parent, "sgp_parent", None):
+                self.sgp_parent.sgp_parent.relax_sensitivity = self.relax_sensitivity
         var_senss = {}
         for var in self.varkeys:
             for i, m in enumerate(self.unsubbed):

gpkit/solution_array.py

@@ -70,9 +70,14 @@ def tight_table(self, _, ntightconstrs=5, tight_senss=1e-2, **kwargs):
     if not self.model:
         return []
     title = "Tightest Constraints"
-    data = [((-float("%+6.2g" % c.relax_sensitivity), str(c)),
-             "%+6.2g" % c.relax_sensitivity, id(c), c)
-            for c in self.model.flat() if c.relax_sensitivity >= tight_senss]
+    try:
+        data = [((-float("%+6.2g" % c.relax_sensitivity), str(c)),
+                 "%+6.2g" % c.relax_sensitivity, id(c), c)
+                for c in self.model.flat()
+                if c.relax_sensitivity >= tight_senss]
+    except AttributeError:
+        print("Constraint %s had no `relax_sensitivity` attribute." % c)
+        return []
     if not data:
         lines = ["No constraints had a sensitivity above %+5.1g."
                  % tight_senss]