diff --git a/exp/geometry.py b/exp/geometry.py
--- a/exp/geometry.py
+++ b/exp/geometry.py
@@ -41,8 +41,24 @@ class Line:
 		(a,b,c)=self.toNormal()
 		return abs(a*point.x+b*point.y+c) # a**2 + b**2 == 1 for Hesse normal form
 
-	def __str__(self): return "({0},{1})".format(self._alpha,self._d)
-	def __repr__(self): return "Line({0},{1})".format(repr(self._alpha),repr(self._d))
+	def shiftBasis(self,newBasis):
+		(a,b,c)=self.toNormal()
+		if a!=0:
+			point=EPoint(-c/a,0)
+		else:
+			point=EPoint(0,-c/b)
+		(x_,y_)=point-newBasis
+		c_=-a*x_-b*y_
+		return Line.fromNormal(a,b,c_)
+
+	@property
+	def alpha(self): return self._alpha
+
+	@property
+	def d(self): return self._d
+
+	def __str__(self): return "Line({0},{1})".format(round(self._alpha,3),round(self._d))
+	def __repr__(self): return "Line({0},{1})".format(self._alpha,self._d)
 
 
 def angleDiff(alpha,beta):