Remove warnings supression as noted by Issue #229 (#231)

* Remove warnings supression as noted by Issue #229

* remove the import of warnings module as not needed now

Author: mmcky

quantecon/arma.py

@@ -4,17 +4,14 @@
 
 Provides functions for working with and visualizing scalar ARMA processes.
 
+TODO: 1. Fix warnings concerning casting complex variables back to floats
+
 """
 import numpy as np
 from numpy import conj, pi
 import matplotlib.pyplot as plt
 from scipy.signal import dimpulse, freqz, dlsim
 
-# == Ignore unnecessary warnings concerning casting complex variables back to
-# floats == #
-import warnings
-warnings.filterwarnings('ignore')
-
 
 class ARMA(object):
     r"""

quantecon/matrix_eqn.py

@@ -7,20 +7,16 @@
 * Lyapunov Equations
 * Ricatti Equations
 
-TODO: See issue 47 on github repository, should add support for
+TODO: 1. See issue 47 on github repository, should add support for
       Sylvester equations
-
+      2. Fix warnings from checking conditioning of matrices
 """
 from __future__ import division
 import numpy as np
-import warnings
 from numpy import dot
 from numpy.linalg import solve
 from scipy.linalg import solve_discrete_lyapunov as sp_solve_discrete_lyapunov
 
-# == Suppress warnings from checking conditioning of matrices == #
-warnings.simplefilter("ignore", RuntimeWarning)
-
 
 def solve_discrete_lyapunov(A, B, max_it=50, method="doubling"):
     r"""