old_contents: """
  Copyright 2017 Robin Verschueren
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  """
  
  import numpy as np
  
  from cvxpy.atoms.quad_form import SymbolicQuadForm
  from cvxpy.expressions.constants import Constant
  from cvxpy.expressions.variable import Variable
  
  
  def power_canon(expr, args):
      affine_expr = args[0]
      p = float(expr.p.value)
      if expr.is_constant():
          return Constant(expr.value), []
      elif p == 0:
          return np.ones(affine_expr.shape), []
      elif p == 1:
          return affine_expr, []
      elif p == 2:
          if isinstance(affine_expr, Variable):
              return SymbolicQuadForm(affine_expr, np.eye(affine_expr.size), expr), []
          else:
              t = Variable(affine_expr.shape)
              return SymbolicQuadForm(t, np.eye(t.size), expr), [affine_expr == t]
      raise ValueError("non-constant quadratic forms can't be raised to a power "
                       "greater than 2.")
  
new_contents: """
  Copyright 2017 Robin Verschueren
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  """
  
  import numpy as np
  import scipy.sparse as sp
  
  from cvxpy.atoms.quad_form import SymbolicQuadForm
  from cvxpy.expressions.constants import Constant
  from cvxpy.expressions.variable import Variable
  
  
  def power_canon(expr, args):
      affine_expr = args[0]
      p = float(expr.p.value)
      if expr.is_constant():
          return Constant(expr.value), []
      elif p == 0:
          return np.ones(affine_expr.shape), []
      elif p == 1:
          return affine_expr, []
      elif p == 2:
          if isinstance(affine_expr, Variable):
              return SymbolicQuadForm(affine_expr, sp.eye(affine_expr.size), expr), []
          else:
              t = Variable(affine_expr.shape)
              return SymbolicQuadForm(t, sp.eye(t.size), expr), [affine_expr == t]
      raise ValueError("non-constant quadratic forms can't be raised to a power "
                       "greater than 2.")
  
subject: replace np.eye with sp.eye (#1143)