problems with quotations in python code

doc/src/week46/week46.do.txt

@@ -1158,15 +1158,15 @@ The following code solves the equations for us
 import numpy
 from cvxopt import matrix
 from cvxopt import solvers
-P = matrix(numpy.diag([1,0]), tc=’d’)
-q = matrix(numpy.array([3,4]), tc=’d’)
-G = matrix(numpy.array([[-1,0],[0,-1],[-1,-3],[2,5],[3,4]]), tc=’d’)
-h = matrix(numpy.array([0,0,-15,100,80]), tc=’d’)
+P = matrix(numpy.diag([1,0]), tc='d')
+q = matrix(numpy.array([3,4]), tc='d')
+G = matrix(numpy.array([[-1,0],[0,-1],[-1,-3],[2,5],[3,4]]), tc='d')
+h = matrix(numpy.array([0,0,-15,100,80]), tc='d')
 # Construct the QP, invoke solver
 sol = solvers.qp(P,q,G,h)
 # Extract optimal value and solution
-sol[’x’] 
-sol[’primal objective’]
+sol['x'] 
+sol['primal objective']
 !ec
 
 !split
@@ -1187,7 +1187,6 @@ subject to $\bm{y}^T\bm{\lambda}=0$. Here we defined the vectors $\bm{\lambda} =
 $\bm{y}=[y_1,y_2,\dots,y_n]$. 
 With  the slack constants this leads to the additional constraint $0\leq \lambda_i \leq C$.
 
-_code will be added_