text: """
  Unit test for Linear Programming
  """
  import sys
  
  import numpy as np
  from numpy.testing import (assert_, assert_allclose, assert_equal,
                             assert_array_less, assert_warns, suppress_warnings)
  from pytest import raises as assert_raises
  from scipy.optimize import linprog, OptimizeWarning
  from scipy.optimize._numdiff import approx_derivative
  from scipy.sparse.linalg import MatrixRankWarning
  from scipy.linalg import LinAlgWarning
  import scipy.sparse
  import pytest
  
  has_umfpack = True
  try:
      from scikits.umfpack import UmfpackWarning
  except ImportError:
      has_umfpack = False
  
  has_cholmod = True
  try:
      import sksparse
      from sksparse.cholmod import cholesky as cholmod
  except ImportError:
      has_cholmod = False
  
  
  def _assert_iteration_limit_reached(res, maxiter):
      assert_(not res.success, "Incorrectly reported success")
      assert_(res.success < maxiter, "Incorrectly reported number of iterations")
      assert_equal(res.status, 1, "Failed to report iteration limit reached")
  
  
  def _assert_infeasible(res):
      # res: linprog result object
      assert_(not res.success, "incorrectly reported success")
      assert_equal(res.status, 2, "failed to report infeasible status")
  
  
  def _assert_unbounded(res):
      # res: linprog result object
      assert_(not res.success, "incorrectly reported success")
      assert_equal(res.status, 3, "failed to report unbounded status")
  
  
  def _assert_unable_to_find_basic_feasible_sol(res):
      # res: linprog result object
  
      # The status may be either 2 or 4 depending on why the feasible solution
      # could not be found. If the undelying problem is expected to not have a
      # feasible solution, _assert_infeasible should be used.
      assert_(not res.success, "incorrectly reported success")
      assert_(res.status in (2, 4), "failed to report optimization failure")
  
  
  def _assert_success(res, desired_fun=None, desired_x=None,
                      rtol=1e-8, atol=1e-8):
      # res: linprog result object
      # desired_fun: desired objective function value or None
      # desired_x: desired solution or None
      if not res.success:
          msg = "linprog status {0}, message: {1}".format(res.status,
                                                          res.message)
          raise AssertionError(msg)
  
      assert_equal(res.status, 0)
      if desired_fun is not None:
          assert_allclose(res.fun, desired_fun,
                          err_msg="converged to an unexpected objective value",
                          rtol=rtol, atol=atol)
      if desired_x is not None:
          assert_allclose(res.x, desired_x,
                          err_msg="converged to an unexpected solution",
                          rtol=rtol, atol=atol)
  
  
  def magic_square(n):
      """
      Generates a linear program for which integer solutions represent an
      n x n magic square; binary decision variables represent the presence
      (or absence) of an integer 1 to n^2 in each position of the square.
      """
  
      np.random.seed(0)
      M = n * (n**2 + 1) / 2
  
      numbers = np.arange(n**4) // n**2 + 1
  
      numbers = numbers.reshape(n**2, n, n)
  
      zeros = np.zeros((n**2, n, n))
  
      A_list = []
      b_list = []
  
      # Rule 1: use every number exactly once
      for i in range(n**2):
          A_row = zeros.copy()
          A_row[i, :, :] = 1
          A_list.append(A_row.flatten())
          b_list.append(1)
  
      # Rule 2: Only one number per square
      for i in range(n):
          for j in range(n):
              A_row = zeros.copy()
              A_row[:, i, j] = 1
              A_list.append(A_row.flatten())
              b_list.append(1)
  
      # Rule 3: sum of rows is M
      for i in range(n):
          A_row = zeros.copy()
          A_row[:, i, :] = numbers[:, i, :]
          A_list.append(A_row.flatten())
          b_list.append(M)
  
      # Rule 4: sum of columns is M
      for i in range(n):
          A_row = zeros.copy()
          A_row[:, :, i] = numbers[:, :, i]
          A_list.append(A_row.flatten())
          b_list.append(M)
  
      # Rule 5: sum of diagonals is M
      A_row = zeros.copy()
      A_row[:, range(n), range(n)] = numbers[:, range(n), range(n)]
      A_list.append(A_row.flatten())
      b_list.append(M)
      A_row = zeros.copy()
      A_row[:, range(n), range(-1, -n - 1, -1)] = \
          numbers[:, range(n), range(-1, -n - 1, -1)]
      A_list.append(A_row.flatten())
      b_list.append(M)
  
      A = np.array(np.vstack(A_list), dtype=float)
      b = np.array(b_list, dtype=float)
      c = np.random.rand(A.shape[1])
  
      return A, b, c, numbers
  
  
  def lpgen_2d(m, n):
      """ -> A b c LP test: m*n vars, m+n constraints
          row sums == n/m, col sums == 1
          https://gist.github.com/denis-bz/8647461
      """
      np.random.seed(0)
      c = - np.random.exponential(size=(m, n))
      Arow = np.zeros((m, m * n))
      brow = np.zeros(m)
      for j in range(m):
          j1 = j + 1
          Arow[j, j * n:j1 * n] = 1
          brow[j] = n / m
  
      Acol = np.zeros((n, m * n))
      bcol = np.zeros(n)
      for j in range(n):
          j1 = j + 1
          Acol[j, j::n] = 1
          bcol[j] = 1
  
      A = np.vstack((Arow, Acol))
      b = np.hstack((brow, bcol))
  
      return A, b, c.ravel()
  
  
  def very_random_gen(seed=0):
      np.random.seed(seed)
      m_eq, m_ub, n = 10, 20, 50
      c = np.random.rand(n)-0.5
      A_ub = np.random.rand(m_ub, n)-0.5
      b_ub = np.random.rand(m_ub)-0.5
      A_eq = np.random.rand(m_eq, n)-0.5
      b_eq = np.random.rand(m_eq)-0.5
      lb = -np.random.rand(n)
      ub = np.random.rand(n)
      lb[lb < -np.random.rand()] = -np.inf
      ub[ub > np.random.rand()] = np.inf
      bounds = np.vstack((lb, ub)).T
      return c, A_ub, b_ub, A_eq, b_eq, bounds
  
  
  def nontrivial_problem():
      c = [-1, 8, 4, -6]
      A_ub = [[-7, -7, 6, 9],
              [1, -1, -3, 0],
              [10, -10, -7, 7],
              [6, -1, 3, 4]]
      b_ub = [-3, 6, -6, 6]
      A_eq = [[-10, 1, 1, -8]]
      b_eq = [-4]
      x_star = [101 / 1391, 1462 / 1391, 0, 752 / 1391]
      f_star = 7083 / 1391
      return c, A_ub, b_ub, A_eq, b_eq, x_star, f_star
  
  
  def l1_regression_prob(seed=0, m=8, d=9, n=100):
      '''
      Training data is {(x0, y0), (x1, y2), ..., (xn-1, yn-1)}
          x in R^d
          y in R
      n: number of training samples
      d: dimension of x, i.e. x in R^d
      phi: feature map R^d -> R^m
      m: dimension of feature space
      '''
      np.random.seed(seed)
      phi = np.random.normal(0, 1, size=(m, d))  # random feature mapping
      w_true = np.random.randn(m)
      x = np.random.normal(0, 1, size=(d, n))  # features
      y = w_true @ (phi @ x) + np.random.normal(0, 1e-5, size=n)  # measurements
  
      # construct the problem
      c = np.ones(m+n)
      c[:m] = 0
      A_ub = scipy.sparse.lil_matrix((2*n, n+m))
      idx = 0
      for ii in range(n):
          A_ub[idx, :m] = phi @ x[:, ii]
          A_ub[idx, m+ii] = -1
          A_ub[idx+1, :m] = -1*phi @ x[:, ii]
          A_ub[idx+1, m+ii] = -1
          idx += 2
      A_ub = A_ub.tocsc()
      b_ub = np.zeros(2*n)
      b_ub[0::2] = y
      b_ub[1::2] = -y
      bnds = [(None, None)]*m + [(0, None)]*n
      return c, A_ub, b_ub, bnds
  
  
  def generic_callback_test(self):
      # Check that callback is as advertised
      last_cb = {}
  
      def cb(res):
          message = res.pop('message')
          complete = res.pop('complete')
  
          assert_(res.pop('phase') in (1, 2))
          assert_(res.pop('status') in range(4))
          assert_(isinstance(res.pop('nit'), int))
          assert_(isinstance(complete, bool))
          assert_(isinstance(message, str))
  
          last_cb['x'] = res['x']
          last_cb['fun'] = res['fun']
          last_cb['slack'] = res['slack']
          last_cb['con'] = res['con']
  
      c = np.array([-3, -2])
      A_ub = [[2, 1], [1, 1], [1, 0]]
      b_ub = [10, 8, 4]
      res = linprog(c, A_ub=A_ub, b_ub=b_ub, callback=cb, method=self.method)
  
      _assert_success(res, desired_fun=-18.0, desired_x=[2, 6])
      assert_allclose(last_cb['fun'], res['fun'])
      assert_allclose(last_cb['x'], res['x'])
      assert_allclose(last_cb['con'], res['con'])
      assert_allclose(last_cb['slack'], res['slack'])
  
  
  def test_unknown_solvers_and_options():
      c = np.array([-3, -2])
      A_ub = [[2, 1], [1, 1], [1, 0]]
      b_ub = [10, 8, 4]
  
      assert_raises(ValueError, linprog,
                    c, A_ub=A_ub, b_ub=b_ub, method='ekki-ekki-ekki')
      assert_raises(ValueError, linprog,
                    c, A_ub=A_ub, b_ub=b_ub, method='highs-ekki')
      assert_raises(ValueError, linprog, c, A_ub=A_ub, b_ub=b_ub,
                    options={"rr_method": 'ekki-ekki-ekki'})
  
  
  def test_choose_solver():
      # 'highs' chooses 'dual'
      c = np.array([-3, -2])
      A_ub = [[2, 1], [1, 1], [1, 0]]
      b_ub = [10, 8, 4]
  
      res = linprog(c, A_ub, b_ub, method='highs')
      _assert_success(res, desired_fun=-18.0, desired_x=[2, 6])
  
  
  A_ub = None
  b_ub = None
  A_eq = None
  b_eq = None
  bounds = None
  
  ################
  # Common Tests #
  ################
  
  
  class LinprogCommonTests:
      """
      Base class for `linprog` tests. Generally, each test will be performed
      once for every derived class of LinprogCommonTests, each of which will
      typically change self.options and/or self.method. Effectively, these tests
      are run for many combination of method (simplex, revised simplex, and
      interior point) and options (such as pivoting rule or sparse treatment).
      """
  
      ##################
      # Targeted Tests #
      ##################
  
      def test_callback(self):
          generic_callback_test(self)
  
      def test_disp(self):
          # test that display option does not break anything.
          A, b, c = lpgen_2d(20, 20)
          res = linprog(c, A_ub=A, b_ub=b, method=self.method,
                        options={"disp": True})
          _assert_success(res, desired_fun=-64.049494229)
  
      def test_docstring_example(self):
          # Example from linprog docstring.
          c = [-1, 4]
          A = [[-3, 1], [1, 2]]
          b = [6, 4]
          x0_bounds = (None, None)
          x1_bounds = (-3, None)
          res = linprog(c, A_ub=A, b_ub=b, bounds=(x0_bounds, x1_bounds),
                        options=self.options, method=self.method)
          _assert_success(res, desired_fun=-22)
  
      def test_type_error(self):
          # (presumably) checks that linprog recognizes type errors
          # This is tested more carefully in test__linprog_clean_inputs.py
          c = [1]
          A_eq = [[1]]
          b_eq = "hello"
          assert_raises(TypeError, linprog,
                        c, A_eq=A_eq, b_eq=b_eq,
                        method=self.method, options=self.options)
  
      def test_aliasing_b_ub(self):
          # (presumably) checks that linprog does not modify b_ub
          # This is tested more carefully in test__linprog_clean_inputs.py
          c = np.array([1.0])
          A_ub = np.array([[1.0]])
          b_ub_orig = np.array([3.0])
          b_ub = b_ub_orig.copy()
          bounds = (-4.0, np.inf)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=-4, desired_x=[-4])
          assert_allclose(b_ub_orig, b_ub)
  
      def test_aliasing_b_eq(self):
          # (presumably) checks that linprog does not modify b_eq
          # This is tested more carefully in test__linprog_clean_inputs.py
          c = np.array([1.0])
          A_eq = np.array([[1.0]])
          b_eq_orig = np.array([3.0])
          b_eq = b_eq_orig.copy()
          bounds = (-4.0, np.inf)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=3, desired_x=[3])
          assert_allclose(b_eq_orig, b_eq)
  
      def test_non_ndarray_args(self):
          # (presumably) checks that linprog accepts list in place of arrays
          # This is tested more carefully in test__linprog_clean_inputs.py
          c = [1.0]
          A_ub = [[1.0]]
          b_ub = [3.0]
          A_eq = [[1.0]]
          b_eq = [2.0]
          bounds = (-1.0, 10.0)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=2, desired_x=[2])
  
      def test_unknown_options(self):
          c = np.array([-3, -2])
          A_ub = [[2, 1], [1, 1], [1, 0]]
          b_ub = [10, 8, 4]
  
          def f(c, A_ub=None, b_ub=None, A_eq=None,
                b_eq=None, bounds=None, options={}):
              linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                      method=self.method, options=options)
  
          o = {key: self.options[key] for key in self.options}
          o['spam'] = 42
  
          assert_warns(OptimizeWarning, f,
                       c, A_ub=A_ub, b_ub=b_ub, options=o)
  
      def test_invalid_inputs(self):
  
          def f(c, A_ub=None, b_ub=None, A_eq=None, b_eq=None, bounds=None):
              linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                      method=self.method, options=self.options)
  
          # Test ill-formatted bounds
          assert_raises(ValueError, f, [1, 2, 3], bounds=[(1, 2), (3, 4)])
          assert_raises(ValueError, f, [1, 2, 3], bounds=[(1, 2), (3, 4), (3, 4, 5)])
          assert_raises(ValueError, f, [1, 2, 3], bounds=[(1, -2), (1, 2)])
  
          # Test other invalid inputs
          assert_raises(ValueError, f, [1, 2], A_ub=[[1, 2]], b_ub=[1, 2])
          assert_raises(ValueError, f, [1, 2], A_ub=[[1]], b_ub=[1])
          assert_raises(ValueError, f, [1, 2], A_eq=[[1, 2]], b_eq=[1, 2])
          assert_raises(ValueError, f, [1, 2], A_eq=[[1]], b_eq=[1])
          assert_raises(ValueError, f, [1, 2], A_eq=[1], b_eq=1)
  
          # this last check doesn't make sense for sparse presolve
          if ("_sparse_presolve" in self.options and
                  self.options["_sparse_presolve"]):
              return
              # there aren't 3-D sparse matrices
  
          assert_raises(ValueError, f, [1, 2], A_ub=np.zeros((1, 1, 3)), b_eq=1)
  
      def test_sparse_constraints(self):
          # gh-13559: improve error message for sparse inputs when unsupported
          def f(c, A_ub=None, b_ub=None, A_eq=None, b_eq=None, bounds=None):
              linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                      method=self.method, options=self.options)
  
          np.random.seed(0)
          m = 100
          n = 150
          A_eq = scipy.sparse.rand(m, n, 0.5)
          x_valid = np.random.randn((n))
          c = np.random.randn((n))
          ub = x_valid + np.random.rand((n))
          lb = x_valid - np.random.rand((n))
          bounds = np.column_stack((lb, ub))
          b_eq = A_eq * x_valid
  
          if self.method in {'simplex', 'revised simplex'}:
              # simplex and revised simplex should raise error
              with assert_raises(ValueError, match=f"Method '{self.method}' "
                                 "does not support sparse constraint matrices."):
                  linprog(c=c, A_eq=A_eq, b_eq=b_eq, bounds=bounds,
                          method=self.method, options=self.options)
          else:
              # other methods should succeed
              options = {**self.options}
              if self.method in {'interior-point'}:
                  options['sparse'] = True
  
              res = linprog(c=c, A_eq=A_eq, b_eq=b_eq, bounds=bounds,
                            method=self.method, options=options)
              assert res.success
  
      def test_maxiter(self):
          # test iteration limit w/ Enzo example
          c = [4, 8, 3, 0, 0, 0]
          A = [
              [2, 5, 3, -1, 0, 0],
              [3, 2.5, 8, 0, -1, 0],
              [8, 10, 4, 0, 0, -1]]
          b = [185, 155, 600]
          np.random.seed(0)
          maxiter = 3
          res = linprog(c, A_eq=A, b_eq=b, method=self.method,
                        options={"maxiter": maxiter})
          _assert_iteration_limit_reached(res, maxiter)
          assert_equal(res.nit, maxiter)
  
      def test_bounds_fixed(self):
  
          # Test fixed bounds (upper equal to lower)
          # If presolve option True, test if solution found in presolve (i.e.
          # number of iterations is 0).
          do_presolve = self.options.get('presolve', True)
  
          res = linprog([1], bounds=(1, 1),
                        method=self.method, options=self.options)
          _assert_success(res, 1, 1)
          if do_presolve:
              assert_equal(res.nit, 0)
  
          res = linprog([1, 2, 3], bounds=[(5, 5), (-1, -1), (3, 3)],
                        method=self.method, options=self.options)
          _assert_success(res, 12, [5, -1, 3])
          if do_presolve:
              assert_equal(res.nit, 0)
  
          res = linprog([1, 1], bounds=[(1, 1), (1, 3)],
                        method=self.method, options=self.options)
          _assert_success(res, 2, [1, 1])
          if do_presolve:
              assert_equal(res.nit, 0)
  
          res = linprog([1, 1, 2], A_eq=[[1, 0, 0], [0, 1, 0]], b_eq=[1, 7],
                        bounds=[(-5, 5), (0, 10), (3.5, 3.5)],
                        method=self.method, options=self.options)
          _assert_success(res, 15, [1, 7, 3.5])
          if do_presolve:
              assert_equal(res.nit, 0)
  
      def test_bounds_infeasible(self):
  
          # Test ill-valued bounds (upper less than lower)
          # If presolve option True, test if solution found in presolve (i.e.
          # number of iterations is 0).
          do_presolve = self.options.get('presolve', True)
  
          res = linprog([1], bounds=(1, -2), method=self.method, options=self.options)
          _assert_infeasible(res)
          if do_presolve:
              assert_equal(res.nit, 0)
  
          res = linprog([1], bounds=[(1, -2)], method=self.method, options=self.options)
          _assert_infeasible(res)
          if do_presolve:
              assert_equal(res.nit, 0)
  
          res = linprog([1, 2, 3], bounds=[(5, 0), (1, 2), (3, 4)], method=self.method, options=self.options)
          _assert_infeasible(res)
          if do_presolve:
              assert_equal(res.nit, 0)
  
      def test_bounds_infeasible_2(self):
  
          # Test ill-valued bounds (lower inf, upper -inf)
          # If presolve option True, test if solution found in presolve (i.e.
          # number of iterations is 0).
          # For the simplex method, the cases do not result in an
          # infeasible status, but in a RuntimeWarning. This is a
          # consequence of having _presolve() take care of feasibility
          # checks. See issue gh-11618.
          do_presolve = self.options.get('presolve', True)
          simplex_without_presolve = not do_presolve and self.method == 'simplex'
  
          c = [1, 2, 3]
          bounds_1 = [(1, 2), (np.inf, np.inf), (3, 4)]
          bounds_2 = [(1, 2), (-np.inf, -np.inf), (3, 4)]
  
          if simplex_without_presolve:
              def g(c, bounds):
                  res = linprog(c, bounds=bounds, method=self.method, options=self.options)
                  return res
  
              with pytest.warns(RuntimeWarning):
                  with pytest.raises(IndexError):
                      g(c, bounds=bounds_1)
  
              with pytest.warns(RuntimeWarning):
                  with pytest.raises(IndexError):
                      g(c, bounds=bounds_2)
          else:
              res = linprog(c=c, bounds=bounds_1, method=self.method, options=self.options)
              _assert_infeasible(res)
              if do_presolve:
                  assert_equal(res.nit, 0)
              res = linprog(c=c, bounds=bounds_2, method=self.method, options=self.options)
              _assert_infeasible(res)
              if do_presolve:
                  assert_equal(res.nit, 0)
  
      def test_empty_constraint_1(self):
          c = [-1, -2]
          res = linprog(c, method=self.method, options=self.options)
          _assert_unbounded(res)
  
      def test_empty_constraint_2(self):
          c = [-1, 1, -1, 1]
          bounds = [(0, np.inf), (-np.inf, 0), (-1, 1), (-1, 1)]
          res = linprog(c, bounds=bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
          # Unboundedness detected in presolve requires no iterations
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_empty_constraint_3(self):
          c = [1, -1, 1, -1]
          bounds = [(0, np.inf), (-np.inf, 0), (-1, 1), (-1, 1)]
          res = linprog(c, bounds=bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[0, 0, -1, 1], desired_fun=-2)
  
      def test_inequality_constraints(self):
          # Minimize linear function subject to linear inequality constraints.
          #  http://www.dam.brown.edu/people/huiwang/classes/am121/Archive/simplex_121_c.pdf
          c = np.array([3, 2]) * -1  # maximize
          A_ub = [[2, 1],
                  [1, 1],
                  [1, 0]]
          b_ub = [10, 8, 4]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=-18, desired_x=[2, 6])
  
      def test_inequality_constraints2(self):
          # Minimize linear function subject to linear inequality constraints.
          # http://www.statslab.cam.ac.uk/~ff271/teaching/opt/notes/notes8.pdf
          # (dead link)
          c = [6, 3]
          A_ub = [[0, 3],
                  [-1, -1],
                  [-2, 1]]
          b_ub = [2, -1, -1]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=5, desired_x=[2 / 3, 1 / 3])
  
      def test_bounds_simple(self):
          c = [1, 2]
          bounds = (1, 2)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[1, 1])
  
          bounds = [(1, 2), (1, 2)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[1, 1])
  
      def test_bounded_below_only_1(self):
          c = np.array([1.0])
          A_eq = np.array([[1.0]])
          b_eq = np.array([3.0])
          bounds = (1.0, None)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=3, desired_x=[3])
  
      def test_bounded_below_only_2(self):
          c = np.ones(3)
          A_eq = np.eye(3)
          b_eq = np.array([1, 2, 3])
          bounds = (0.5, np.inf)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=b_eq, desired_fun=np.sum(b_eq))
  
      def test_bounded_above_only_1(self):
          c = np.array([1.0])
          A_eq = np.array([[1.0]])
          b_eq = np.array([3.0])
          bounds = (None, 10.0)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=3, desired_x=[3])
  
      def test_bounded_above_only_2(self):
          c = np.ones(3)
          A_eq = np.eye(3)
          b_eq = np.array([1, 2, 3])
          bounds = (-np.inf, 4)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=b_eq, desired_fun=np.sum(b_eq))
  
      def test_bounds_infinity(self):
          c = np.ones(3)
          A_eq = np.eye(3)
          b_eq = np.array([1, 2, 3])
          bounds = (-np.inf, np.inf)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=b_eq, desired_fun=np.sum(b_eq))
  
      def test_bounds_mixed(self):
          # Problem has one unbounded variable and
          # another with a negative lower bound.
          c = np.array([-1, 4]) * -1  # maximize
          A_ub = np.array([[-3, 1],
                           [1, 2]], dtype=np.float64)
          b_ub = [6, 4]
          x0_bounds = (-np.inf, np.inf)
          x1_bounds = (-3, np.inf)
          bounds = (x0_bounds, x1_bounds)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=-80 / 7, desired_x=[-8 / 7, 18 / 7])
  
      def test_bounds_equal_but_infeasible(self):
          c = [-4, 1]
          A_ub = [[7, -2], [0, 1], [2, -2]]
          b_ub = [14, 0, 3]
          bounds = [(2, 2), (0, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
      def test_bounds_equal_but_infeasible2(self):
          c = [-4, 1]
          A_eq = [[7, -2], [0, 1], [2, -2]]
          b_eq = [14, 0, 3]
          bounds = [(2, 2), (0, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
      def test_bounds_equal_no_presolve(self):
          # There was a bug when a lower and upper bound were equal but
          # presolve was not on to eliminate the variable. The bound
          # was being converted to an equality constraint, but the bound
          # was not eliminated, leading to issues in postprocessing.
          c = [1, 2]
          A_ub = [[1, 2], [1.1, 2.2]]
          b_ub = [4, 8]
          bounds = [(1, 2), (2, 2)]
  
          o = {key: self.options[key] for key in self.options}
          o["presolve"] = False
  
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=o)
          _assert_infeasible(res)
  
      def test_zero_column_1(self):
          m, n = 3, 4
          np.random.seed(0)
          c = np.random.rand(n)
          c[1] = 1
          A_eq = np.random.rand(m, n)
          A_eq[:, 1] = 0
          b_eq = np.random.rand(m)
          A_ub = [[1, 0, 1, 1]]
          b_ub = 3
          bounds = [(-10, 10), (-10, 10), (-10, None), (None, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=-9.7087836730413404)
  
      def test_zero_column_2(self):
          np.random.seed(0)
          m, n = 2, 4
          c = np.random.rand(n)
          c[1] = -1
          A_eq = np.random.rand(m, n)
          A_eq[:, 1] = 0
          b_eq = np.random.rand(m)
  
          A_ub = np.random.rand(m, n)
          A_ub[:, 1] = 0
          b_ub = np.random.rand(m)
          bounds = (None, None)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
          # Unboundedness detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_zero_row_1(self):
          c = [1, 2, 3]
          A_eq = [[0, 0, 0], [1, 1, 1], [0, 0, 0]]
          b_eq = [0, 3, 0]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=3)
  
      def test_zero_row_2(self):
          A_ub = [[0, 0, 0], [1, 1, 1], [0, 0, 0]]
          b_ub = [0, 3, 0]
          c = [1, 2, 3]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=0)
  
      def test_zero_row_3(self):
          m, n = 2, 4
          c = np.random.rand(n)
          A_eq = np.random.rand(m, n)
          A_eq[0, :] = 0
          b_eq = np.random.rand(m)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
          # Infeasibility detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_zero_row_4(self):
          m, n = 2, 4
          c = np.random.rand(n)
          A_ub = np.random.rand(m, n)
          A_ub[0, :] = 0
          b_ub = -np.random.rand(m)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
          # Infeasibility detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_singleton_row_eq_1(self):
          c = [1, 1, 1, 2]
          A_eq = [[1, 0, 0, 0], [0, 2, 0, 0], [1, 0, 0, 0], [1, 1, 1, 1]]
          b_eq = [1, 2, 2, 4]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
          # Infeasibility detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_singleton_row_eq_2(self):
          c = [1, 1, 1, 2]
          A_eq = [[1, 0, 0, 0], [0, 2, 0, 0], [1, 0, 0, 0], [1, 1, 1, 1]]
          b_eq = [1, 2, 1, 4]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=4)
  
      def test_singleton_row_ub_1(self):
          c = [1, 1, 1, 2]
          A_ub = [[1, 0, 0, 0], [0, 2, 0, 0], [-1, 0, 0, 0], [1, 1, 1, 1]]
          b_ub = [1, 2, -2, 4]
          bounds = [(None, None), (0, None), (0, None), (0, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
          # Infeasibility detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_singleton_row_ub_2(self):
          c = [1, 1, 1, 2]
          A_ub = [[1, 0, 0, 0], [0, 2, 0, 0], [-1, 0, 0, 0], [1, 1, 1, 1]]
          b_ub = [1, 2, -0.5, 4]
          bounds = [(None, None), (0, None), (0, None), (0, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=0.5)
  
      def test_infeasible(self):
          # Test linprog response to an infeasible problem
          c = [-1, -1]
          A_ub = [[1, 0],
                  [0, 1],
                  [-1, -1]]
          b_ub = [2, 2, -5]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
      def test_infeasible_inequality_bounds(self):
          c = [1]
          A_ub = [[2]]
          b_ub = 4
          bounds = (5, 6)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_infeasible(res)
  
          # Infeasibility detected in presolve
          if self.options.get('presolve', True):
              assert_equal(res.nit, 0)
  
      def test_unbounded(self):
          # Test linprog response to an unbounded problem
          c = np.array([1, 1]) * -1  # maximize
          A_ub = [[-1, 1],
                  [-1, -1]]
          b_ub = [-1, -2]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
  
      def test_unbounded_below_no_presolve_corrected(self):
          c = [1]
          bounds = [(None, 1)]
  
          o = {key: self.options[key] for key in self.options}
          o["presolve"] = False
  
          res = linprog(c=c, bounds=bounds,
                        method=self.method,
                        options=o)
          if self.method == "revised simplex":
              # Revised simplex has a special pathway for no constraints.
              assert_equal(res.status, 5)
          else:
              _assert_unbounded(res)
  
      def test_unbounded_no_nontrivial_constraints_1(self):
          """
          Test whether presolve pathway for detecting unboundedness after
          constraint elimination is working.
          """
          c = np.array([0, 0, 0, 1, -1, -1])
          A_ub = np.array([[1, 0, 0, 0, 0, 0],
                           [0, 1, 0, 0, 0, 0],
                           [0, 0, 0, 0, 0, -1]])
          b_ub = np.array([2, -2, 0])
          bounds = [(None, None), (None, None), (None, None),
                    (-1, 1), (-1, 1), (0, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
          if not self.method.lower().startswith("highs"):
              assert_equal(res.x[-1], np.inf)
              assert_equal(res.message[:36],
                           "The problem is (trivially) unbounded")
  
      def test_unbounded_no_nontrivial_constraints_2(self):
          """
          Test whether presolve pathway for detecting unboundedness after
          constraint elimination is working.
          """
          c = np.array([0, 0, 0, 1, -1, 1])
          A_ub = np.array([[1, 0, 0, 0, 0, 0],
                           [0, 1, 0, 0, 0, 0],
                           [0, 0, 0, 0, 0, 1]])
          b_ub = np.array([2, -2, 0])
          bounds = [(None, None), (None, None), (None, None),
                    (-1, 1), (-1, 1), (None, 0)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
          if not self.method.lower().startswith("highs"):
              assert_equal(res.x[-1], -np.inf)
              assert_equal(res.message[:36],
                           "The problem is (trivially) unbounded")
  
      def test_cyclic_recovery(self):
          # Test linprogs recovery from cycling using the Klee-Minty problem
          # Klee-Minty  https://www.math.ubc.ca/~israel/m340/kleemin3.pdf
          c = np.array([100, 10, 1]) * -1  # maximize
          A_ub = [[1, 0, 0],
                  [20, 1, 0],
                  [200, 20, 1]]
          b_ub = [1, 100, 10000]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[0, 0, 10000], atol=5e-6, rtol=1e-7)
  
      def test_cyclic_bland(self):
          # Test the effect of Bland's rule on a cycling problem
          c = np.array([-10, 57, 9, 24.])
          A_ub = np.array([[0.5, -5.5, -2.5, 9],
                           [0.5, -1.5, -0.5, 1],
                           [1, 0, 0, 0]])
          b_ub = [0, 0, 1]
  
          # copy the existing options dictionary but change maxiter
          maxiter = 100
          o = {key: val for key, val in self.options.items()}
          o['maxiter'] = maxiter
  
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=o)
  
          if self.method == 'simplex' and not self.options.get('bland'):
              # simplex cycles without Bland's rule
              _assert_iteration_limit_reached(res, o['maxiter'])
          else:
              # other methods, including simplex with Bland's rule, succeed
              _assert_success(res, desired_x=[1, 0, 1, 0])
          # note that revised simplex skips this test because it may or may not
          # cycle depending on the initial basis
  
      def test_remove_redundancy_infeasibility(self):
          # mostly a test of redundancy removal, which is carefully tested in
          # test__remove_redundancy.py
          m, n = 10, 10
          c = np.random.rand(n)
          A_eq = np.random.rand(m, n)
          b_eq = np.random.rand(m)
          A_eq[-1, :] = 2 * A_eq[-2, :]
          b_eq[-1] *= -1
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_infeasible(res)
  
      #################
      # General Tests #
      #################
  
      def test_nontrivial_problem(self):
          # Problem involves all constraint types,
          # negative resource limits, and rounding issues.
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
  
      def test_lpgen_problem(self):
          # Test linprog  with a rather large problem (400 variables,
          # 40 constraints) generated by https://gist.github.com/denis-bz/8647461
          A_ub, b_ub, c = lpgen_2d(20, 20)
  
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "Solving system with option 'sym_pos'")
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=-64.049494229)
  
      def test_network_flow(self):
          # A network flow problem with supply and demand at nodes
          # and with costs along directed edges.
          # https://www.princeton.edu/~rvdb/542/lectures/lec10.pdf
          c = [2, 4, 9, 11, 4, 3, 8, 7, 0, 15, 16, 18]
          n, p = -1, 1
          A_eq = [
              [n, n, p, 0, p, 0, 0, 0, 0, p, 0, 0],
              [p, 0, 0, p, 0, p, 0, 0, 0, 0, 0, 0],
              [0, 0, n, n, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, p, p, 0, 0, p, 0],
              [0, 0, 0, 0, n, n, n, 0, p, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, n, n, 0, 0, p],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, n, n, n]]
          b_eq = [0, 19, -16, 33, 0, 0, -36]
          with suppress_warnings() as sup:
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=755, atol=1e-6, rtol=1e-7)
  
      def test_network_flow_limited_capacity(self):
          # A network flow problem with supply and demand at nodes
          # and with costs and capacities along directed edges.
          # http://blog.sommer-forst.de/2013/04/10/
          c = [2, 2, 1, 3, 1]
          bounds = [
              [0, 4],
              [0, 2],
              [0, 2],
              [0, 3],
              [0, 5]]
          n, p = -1, 1
          A_eq = [
              [n, n, 0, 0, 0],
              [p, 0, n, n, 0],
              [0, p, p, 0, n],
              [0, 0, 0, p, p]]
          b_eq = [-4, 0, 0, 4]
  
          with suppress_warnings() as sup:
              # this is an UmfpackWarning but I had trouble importing it
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(RuntimeWarning, "scipy.linalg.solve\nIll...")
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              sup.filter(OptimizeWarning, "Solving system with option...")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=14)
  
      def test_simplex_algorithm_wikipedia_example(self):
          # https://en.wikipedia.org/wiki/Simplex_algorithm#Example
          c = [-2, -3, -4]
          A_ub = [
              [3, 2, 1],
              [2, 5, 3]]
          b_ub = [10, 15]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=-20)
  
      def test_enzo_example(self):
          # https://github.com/scipy/scipy/issues/1779 lp2.py
          #
          # Translated from Octave code at:
          # http://www.ecs.shimane-u.ac.jp/~kyoshida/lpeng.htm
          # and placed under MIT licence by Enzo Michelangeli
          # with permission explicitly granted by the original author,
          # Prof. Kazunobu Yoshida
          c = [4, 8, 3, 0, 0, 0]
          A_eq = [
              [2, 5, 3, -1, 0, 0],
              [3, 2.5, 8, 0, -1, 0],
              [8, 10, 4, 0, 0, -1]]
          b_eq = [185, 155, 600]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=317.5,
                          desired_x=[66.25, 0, 17.5, 0, 183.75, 0],
                          atol=6e-6, rtol=1e-7)
  
      def test_enzo_example_b(self):
          # rescued from https://github.com/scipy/scipy/pull/218
          c = [2.8, 6.3, 10.8, -2.8, -6.3, -10.8]
          A_eq = [[-1, -1, -1, 0, 0, 0],
                  [0, 0, 0, 1, 1, 1],
                  [1, 0, 0, 1, 0, 0],
                  [0, 1, 0, 0, 1, 0],
                  [0, 0, 1, 0, 0, 1]]
          b_eq = [-0.5, 0.4, 0.3, 0.3, 0.3]
  
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=-1.77,
                          desired_x=[0.3, 0.2, 0.0, 0.0, 0.1, 0.3])
  
      def test_enzo_example_c_with_degeneracy(self):
          # rescued from https://github.com/scipy/scipy/pull/218
          m = 20
          c = -np.ones(m)
          tmp = 2 * np.pi * np.arange(1, m + 1) / (m + 1)
          A_eq = np.vstack((np.cos(tmp) - 1, np.sin(tmp)))
          b_eq = [0, 0]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=0, desired_x=np.zeros(m))
  
      def test_enzo_example_c_with_unboundedness(self):
          # rescued from https://github.com/scipy/scipy/pull/218
          m = 50
          c = -np.ones(m)
          tmp = 2 * np.pi * np.arange(m) / (m + 1)
          A_eq = np.vstack((np.cos(tmp) - 1, np.sin(tmp)))
          b_eq = [0, 0]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_unbounded(res)
  
      def test_enzo_example_c_with_infeasibility(self):
          # rescued from https://github.com/scipy/scipy/pull/218
          m = 50
          c = -np.ones(m)
          tmp = 2 * np.pi * np.arange(m) / (m + 1)
          A_eq = np.vstack((np.cos(tmp) - 1, np.sin(tmp)))
          b_eq = [1, 1]
  
          o = {key: self.options[key] for key in self.options}
          o["presolve"] = False
  
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=o)
          _assert_infeasible(res)
  
      def test_basic_artificial_vars(self):
          # Problem is chosen to test two phase simplex methods when at the end
          # of phase 1 some artificial variables remain in the basis.
          # Also, for `method='simplex'`, the row in the tableau corresponding
          # with the artificial variables is not all zero.
          c = np.array([-0.1, -0.07, 0.004, 0.004, 0.004, 0.004])
          A_ub = np.array([[1.0, 0, 0, 0, 0, 0], [-1.0, 0, 0, 0, 0, 0],
                           [0, -1.0, 0, 0, 0, 0], [0, 1.0, 0, 0, 0, 0],
                           [1.0, 1.0, 0, 0, 0, 0]])
          b_ub = np.array([3.0, 3.0, 3.0, 3.0, 20.0])
          A_eq = np.array([[1.0, 0, -1, 1, -1, 1], [0, -1.0, -1, 1, -1, 1]])
          b_eq = np.array([0, 0])
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=0, desired_x=np.zeros_like(c),
                          atol=2e-6)
  
      def test_optimize_result(self):
          # check all fields in OptimizeResult
          c, A_ub, b_ub, A_eq, b_eq, bounds = very_random_gen(0)
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq=b_eq,
                        bounds=bounds, method=self.method, options=self.options)
          assert_(res.success)
          assert_(res.nit)
          assert_(not res.status)
          assert_(res.message == "Optimization terminated successfully.")
          assert_allclose(c @ res.x, res.fun)
          assert_allclose(b_eq - A_eq @ res.x, res.con, atol=1e-11)
          assert_allclose(b_ub - A_ub @ res.x, res.slack, atol=1e-11)
  
      #################
      # Bug Fix Tests #
      #################
  
      def test_bug_5400(self):
          # https://github.com/scipy/scipy/issues/5400
          bounds = [
              (0, None),
              (0, 100), (0, 100), (0, 100), (0, 100), (0, 100), (0, 100),
              (0, 900), (0, 900), (0, 900), (0, 900), (0, 900), (0, 900),
              (0, None), (0, None), (0, None), (0, None), (0, None), (0, None)]
  
          f = 1 / 9
          g = -1e4
          h = -3.1
          A_ub = np.array([
              [1, -2.99, 0, 0, -3, 0, 0, 0, -1, -1, 0, -1, -1, 1, 1, 0, 0, 0, 0],
              [1, 0, -2.9, h, 0, -3, 0, -1, 0, 0, -1, 0, -1, 0, 0, 1, 1, 0, 0],
              [1, 0, 0, h, 0, 0, -3, -1, -1, 0, -1, -1, 0, 0, 0, 0, 0, 1, 1],
              [0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, 0],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1],
              [0, 1.99, -1, -1, 0, 0, 0, -1, f, f, 0, 0, 0, g, 0, 0, 0, 0, 0],
              [0, 0, 0, 0, 2, -1, -1, 0, 0, 0, -1, f, f, 0, g, 0, 0, 0, 0],
              [0, -1, 1.9, 2.1, 0, 0, 0, f, -1, -1, 0, 0, 0, 0, 0, g, 0, 0, 0],
              [0, 0, 0, 0, -1, 2, -1, 0, 0, 0, f, -1, f, 0, 0, 0, g, 0, 0],
              [0, -1, -1, 2.1, 0, 0, 0, f, f, -1, 0, 0, 0, 0, 0, 0, 0, g, 0],
              [0, 0, 0, 0, -1, -1, 2, 0, 0, 0, f, f, -1, 0, 0, 0, 0, 0, g]])
  
          b_ub = np.array([
              0.0, 0, 0, 100, 100, 100, 100, 100, 100, 900, 900, 900, 900, 900,
              900, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0])
  
          c = np.array([-1.0, 1, 1, 1, 1, 1, 1, 1, 1,
                        1, 1, 1, 1, 0, 0, 0, 0, 0, 0])
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning,
                         "Solving system with option 'sym_pos'")
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=-106.63507541835018)
  
      def test_bug_6139(self):
          # linprog(method='simplex') fails to find a basic feasible solution
          # if phase 1 pseudo-objective function is outside the provided tol.
          # https://github.com/scipy/scipy/issues/6139
  
          # Note: This is not strictly a bug as the default tolerance determines
          # if a result is "close enough" to zero and should not be expected
          # to work for all cases.
  
          c = np.array([1, 1, 1])
          A_eq = np.array([[1., 0., 0.], [-1000., 0., - 1000.]])
          b_eq = np.array([5.00000000e+00, -1.00000000e+04])
          A_ub = -np.array([[0., 1000000., 1010000.]])
          b_ub = -np.array([10000000.])
          bounds = (None, None)
  
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
  
          _assert_success(res, desired_fun=14.95,
                          desired_x=np.array([5, 4.95, 5]))
  
      def test_bug_6690(self):
          # linprog simplex used to violate bound constraint despite reporting
          # success.
          # https://github.com/scipy/scipy/issues/6690
  
          A_eq = np.array([[0, 0, 0, 0.93, 0, 0.65, 0, 0, 0.83, 0]])
          b_eq = np.array([0.9626])
          A_ub = np.array([
              [0, 0, 0, 1.18, 0, 0, 0, -0.2, 0, -0.22],
              [0, 0, 0, 0, 0, 0, 0, 0, 0, 0],
              [0, 0, 0, 0.43, 0, 0, 0, 0, 0, 0],
              [0, -1.22, -0.25, 0, 0, 0, -2.06, 0, 0, 1.37],
              [0, 0, 0, 0, 0, 0, 0, -0.25, 0, 0]
          ])
          b_ub = np.array([0.615, 0, 0.172, -0.869, -0.022])
          bounds = np.array([
              [-0.84, -0.97, 0.34, 0.4, -0.33, -0.74, 0.47, 0.09, -1.45, -0.73],
              [0.37, 0.02, 2.86, 0.86, 1.18, 0.5, 1.76, 0.17, 0.32, -0.15]
          ]).T
          c = np.array([
              -1.64, 0.7, 1.8, -1.06, -1.16, 0.26, 2.13, 1.53, 0.66, 0.28
              ])
  
          with suppress_warnings() as sup:
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(OptimizeWarning,
                         "Solving system with option 'cholesky'")
              sup.filter(OptimizeWarning, "Solving system with option 'sym_pos'")
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
  
          desired_fun = -1.19099999999
          desired_x = np.array([0.3700, -0.9700, 0.3400, 0.4000, 1.1800,
                                0.5000, 0.4700, 0.0900, 0.3200, -0.7300])
          _assert_success(res, desired_fun=desired_fun, desired_x=desired_x)
  
          # Add small tol value to ensure arrays are less than or equal.
          atol = 1e-6
          assert_array_less(bounds[:, 0] - atol, res.x)
          assert_array_less(res.x, bounds[:, 1] + atol)
  
      def test_bug_7044(self):
          # linprog simplex failed to "identify correct constraints" (?)
          # leading to a non-optimal solution if A is rank-deficient.
          # https://github.com/scipy/scipy/issues/7044
  
          A_eq, b_eq, c, N = magic_square(3)
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
  
          desired_fun = 1.730550597
          _assert_success(res, desired_fun=desired_fun)
          assert_allclose(A_eq.dot(res.x), b_eq)
          assert_array_less(np.zeros(res.x.size) - 1e-5, res.x)
  
      def test_bug_7237(self):
          # https://github.com/scipy/scipy/issues/7237
          # linprog simplex "explodes" when the pivot value is very
          # close to zero.
  
          c = np.array([-1, 0, 0, 0, 0, 0, 0, 0, 0])
          A_ub = np.array([
              [1., -724., 911., -551., -555., -896., 478., -80., -293.],
              [1., 566., 42., 937., 233., 883., 392., -909., 57.],
              [1., -208., -894., 539., 321., 532., -924., 942., 55.],
              [1., 857., -859., 83., 462., -265., -971., 826., 482.],
              [1., 314., -424., 245., -424., 194., -443., -104., -429.],
              [1., 540., 679., 361., 149., -827., 876., 633., 302.],
              [0., -1., -0., -0., -0., -0., -0., -0., -0.],
              [0., -0., -1., -0., -0., -0., -0., -0., -0.],
              [0., -0., -0., -1., -0., -0., -0., -0., -0.],
              [0., -0., -0., -0., -1., -0., -0., -0., -0.],
              [0., -0., -0., -0., -0., -1., -0., -0., -0.],
              [0., -0., -0., -0., -0., -0., -1., -0., -0.],
              [0., -0., -0., -0., -0., -0., -0., -1., -0.],
              [0., -0., -0., -0., -0., -0., -0., -0., -1.],
              [0., 1., 0., 0., 0., 0., 0., 0., 0.],
              [0., 0., 1., 0., 0., 0., 0., 0., 0.],
              [0., 0., 0., 1., 0., 0., 0., 0., 0.],
              [0., 0., 0., 0., 1., 0., 0., 0., 0.],
              [0., 0., 0., 0., 0., 1., 0., 0., 0.],
              [0., 0., 0., 0., 0., 0., 1., 0., 0.],
              [0., 0., 0., 0., 0., 0., 0., 1., 0.],
              [0., 0., 0., 0., 0., 0., 0., 0., 1.]
              ])
          b_ub = np.array([
              0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.,
              0., 0., 0., 1., 1., 1., 1., 1., 1., 1., 1.])
          A_eq = np.array([[0., 1., 1., 1., 1., 1., 1., 1., 1.]])
          b_eq = np.array([[1.]])
          bounds = [(None, None)] * 9
  
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_fun=108.568535, atol=1e-6)
  
      def test_bug_8174(self):
          # https://github.com/scipy/scipy/issues/8174
          # The simplex method sometimes "explodes" if the pivot value is very
          # close to zero.
          A_ub = np.array([
              [22714, 1008, 13380, -2713.5, -1116],
              [-4986, -1092, -31220, 17386.5, 684],
              [-4986, 0, 0, -2713.5, 0],
              [22714, 0, 0, 17386.5, 0]])
          b_ub = np.zeros(A_ub.shape[0])
          c = -np.ones(A_ub.shape[1])
          bounds = [(0, 1)] * A_ub.shape[1]
          with suppress_warnings() as sup:
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
  
          if self.options.get('tol', 1e-9) < 1e-10 and self.method == 'simplex':
              _assert_unable_to_find_basic_feasible_sol(res)
          else:
              _assert_success(res, desired_fun=-2.0080717488789235, atol=1e-6)
  
      def test_bug_8174_2(self):
          # Test supplementary example from issue 8174.
          # https://github.com/scipy/scipy/issues/8174
          # https://stackoverflow.com/questions/47717012/linprog-in-scipy-optimize-checking-solution
          c = np.array([1, 0, 0, 0, 0, 0, 0])
          A_ub = -np.identity(7)
          b_ub = np.array([[-2], [-2], [-2], [-2], [-2], [-2], [-2]])
          A_eq = np.array([
              [1, 1, 1, 1, 1, 1, 0],
              [0.3, 1.3, 0.9, 0, 0, 0, -1],
              [0.3, 0, 0, 0, 0, 0, -2/3],
              [0, 0.65, 0, 0, 0, 0, -1/15],
              [0, 0, 0.3, 0, 0, 0, -1/15]
          ])
          b_eq = np.array([[100], [0], [0], [0], [0]])
  
          with suppress_warnings() as sup:
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_fun=43.3333333331385)
  
      def test_bug_8561(self):
          # Test that pivot row is chosen correctly when using Bland's rule
          # This was originally written for the simplex method with
          # Bland's rule only, but it doesn't hurt to test all methods/options
          # https://github.com/scipy/scipy/issues/8561
          c = np.array([7, 0, -4, 1.5, 1.5])
          A_ub = np.array([
              [4, 5.5, 1.5, 1.0, -3.5],
              [1, -2.5, -2, 2.5, 0.5],
              [3, -0.5, 4, -12.5, -7],
              [-1, 4.5, 2, -3.5, -2],
              [5.5, 2, -4.5, -1, 9.5]])
          b_ub = np.array([0, 0, 0, 0, 1])
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, options=self.options,
                        method=self.method)
          _assert_success(res, desired_x=[0, 0, 19, 16/3, 29/3])
  
      def test_bug_8662(self):
          # linprog simplex used to report incorrect optimal results
          # https://github.com/scipy/scipy/issues/8662
          c = [-10, 10, 6, 3]
          A_ub = [[8, -8, -4, 6],
                  [-8, 8, 4, -6],
                  [-4, 4, 8, -4],
                  [3, -3, -3, -10]]
          b_ub = [9, -9, -9, -4]
          bounds = [(0, None), (0, None), (0, None), (0, None)]
          desired_fun = 36.0000000000
  
          with suppress_warnings() as sup:
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res1 = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                             method=self.method, options=self.options)
  
          # Set boundary condition as a constraint
          A_ub.append([0, 0, -1, 0])
          b_ub.append(0)
          bounds[2] = (None, None)
  
          with suppress_warnings() as sup:
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res2 = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                             method=self.method, options=self.options)
          rtol = 1e-5
          _assert_success(res1, desired_fun=desired_fun, rtol=rtol)
          _assert_success(res2, desired_fun=desired_fun, rtol=rtol)
  
      def test_bug_8663(self):
          # exposed a bug in presolve
          # https://github.com/scipy/scipy/issues/8663
          c = [1, 5]
          A_eq = [[0, -7]]
          b_eq = [-6]
          bounds = [(0, None), (None, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[0, 6./7], desired_fun=5*6./7)
  
      def test_bug_8664(self):
          # interior-point has trouble with this when presolve is off
          # tested for interior-point with presolve off in TestLinprogIPSpecific
          # https://github.com/scipy/scipy/issues/8664
          c = [4]
          A_ub = [[2], [5]]
          b_ub = [4, 4]
          A_eq = [[0], [-8], [9]]
          b_eq = [3, 2, 10]
          with suppress_warnings() as sup:
              sup.filter(RuntimeWarning)
              sup.filter(OptimizeWarning, "Solving system with option...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_infeasible(res)
  
      def test_bug_8973(self):
          """
          Test whether bug described at:
          https://github.com/scipy/scipy/issues/8973
          was fixed.
          """
          c = np.array([0, 0, 0, 1, -1])
          A_ub = np.array([[1, 0, 0, 0, 0], [0, 1, 0, 0, 0]])
          b_ub = np.array([2, -2])
          bounds = [(None, None), (None, None), (None, None), (-1, 1), (-1, 1)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          # solution vector x is not unique
          _assert_success(res, desired_fun=-2)
          # HiGHS IPM had an issue where the following wasn't true!
          assert_equal(c @ res.x, res.fun)
  
      def test_bug_8973_2(self):
          """
          Additional test for:
          https://github.com/scipy/scipy/issues/8973
          suggested in
          https://github.com/scipy/scipy/pull/8985
          review by @antonior92
          """
          c = np.zeros(1)
          A_ub = np.array([[1]])
          b_ub = np.array([-2])
          bounds = (None, None)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options)
          _assert_success(res, desired_x=[-2], desired_fun=0)
  
      def test_bug_10124(self):
          """
          Test for linprog docstring problem
          'disp'=True caused revised simplex failure
          """
          c = np.zeros(1)
          A_ub = np.array([[1]])
          b_ub = np.array([-2])
          bounds = (None, None)
          c = [-1, 4]
          A_ub = [[-3, 1], [1, 2]]
          b_ub = [6, 4]
          bounds = [(None, None), (-3, None)]
          o = {"disp": True}
          o.update(self.options)
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=o)
          _assert_success(res, desired_x=[10, -3], desired_fun=-22)
  
      def test_bug_10349(self):
          """
          Test for redundancy removal tolerance issue
          https://github.com/scipy/scipy/issues/10349
          """
          A_eq = np.array([[1, 1, 0, 0, 0, 0],
                           [0, 0, 1, 1, 0, 0],
                           [0, 0, 0, 0, 1, 1],
                           [1, 0, 1, 0, 0, 0],
                           [0, 0, 0, 1, 1, 0],
                           [0, 1, 0, 0, 0, 1]])
          b_eq = np.array([221, 210, 10, 141, 198, 102])
          c = np.concatenate((0, 1, np.zeros(4)), axis=None)
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=self.options)
          _assert_success(res, desired_x=[129, 92, 12, 198, 0, 10], desired_fun=92)
  
      @pytest.mark.skipif(sys.platform == 'darwin',
                          reason=("Failing on some local macOS builds, "
                                  "see gh-13846"))
      def test_bug_10466(self):
          """
          Test that autoscale fixes poorly-scaled problem
          """
          c = [-8., -0., -8., -0., -8., -0., -0., -0., -0., -0., -0., -0., -0.]
          A_eq = [[1., 1., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
                  [0., 0., 1., 1., 0., 0., 0., 0., 0., 0., 0., 0., 0.],
                  [0., 0., 0., 0., 1., 1., 0., 0., 0., 0., 0., 0., 0.],
                  [1., 0., 1., 0., 1., 0., -1., 0., 0., 0., 0., 0., 0.],
                  [1., 0., 1., 0., 1., 0., 0., 1., 0., 0., 0., 0., 0.],
                  [1., 0., 0., 0., 0., 0., 0., 0., 1., 0., 0., 0., 0.],
                  [1., 0., 0., 0., 0., 0., 0., 0., 0., 1., 0., 0., 0.],
                  [1., 0., 1., 0., 1., 0., 0., 0., 0., 0., 1., 0., 0.],
                  [0., 0., 1., 0., 1., 0., 0., 0., 0., 0., 0., 1., 0.],
                  [0., 0., 1., 0., 1., 0., 0., 0., 0., 0., 0., 0., 1.]]
  
          b_eq = [3.14572800e+08, 4.19430400e+08, 5.24288000e+08,
                  1.00663296e+09, 1.07374182e+09, 1.07374182e+09,
                  1.07374182e+09, 1.07374182e+09, 1.07374182e+09,
                  1.07374182e+09]
  
          o = {}
          # HiGHS methods don't use autoscale option
          if not self.method.startswith("highs"):
              o = {"autoscale": True}
          o.update(self.options)
  
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "Solving system with option...")
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(RuntimeWarning, "scipy.linalg.solve\nIll...")
              sup.filter(RuntimeWarning, "divide by zero encountered...")
              sup.filter(RuntimeWarning, "overflow encountered...")
              sup.filter(RuntimeWarning, "invalid value encountered...")
              sup.filter(LinAlgWarning, "Ill-conditioned matrix...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=o)
          assert_allclose(res.fun, -8589934560)
  
  #########################
  # Method-specific Tests #
  #########################
  
  
  class LinprogSimplexTests(LinprogCommonTests):
      method = "simplex"
  
  
  class LinprogIPTests(LinprogCommonTests):
      method = "interior-point"
  
  
  class LinprogRSTests(LinprogCommonTests):
      method = "revised simplex"
  
      # Revised simplex does not reliably solve these problems.
      # Failure is intermittent due to the random choice of elements to complete
      # the basis after phase 1 terminates. In any case, linprog exists
      # gracefully, reporting numerical difficulties. I do not think this should
      # prevent revised simplex from being merged, as it solves the problems
      # most of the time and solves a broader range of problems than the existing
      # simplex implementation.
      # I believe that the root cause is the same for all three and that this
      # same issue prevents revised simplex from solving many other problems
      # reliably. Somehow the pivoting rule allows the algorithm to pivot into
      # a singular basis. I haven't been able to find a reference that
      # acknowledges this possibility, suggesting that there is a bug. On the
      # other hand, the pivoting rule is quite simple, and I can't find a
      # mistake, which suggests that this is a possibility with the pivoting
      # rule. Hopefully, a better pivoting rule will fix the issue.
  
      def test_bug_5400(self):
          pytest.skip("Intermittent failure acceptable.")
  
      def test_bug_8662(self):
          pytest.skip("Intermittent failure acceptable.")
  
      def test_network_flow(self):
          pytest.skip("Intermittent failure acceptable.")
  
  
  class LinprogHiGHSTests(LinprogCommonTests):
      def test_callback(self):
          # this is the problem from test_callback
          cb = lambda res: None
          c = np.array([-3, -2])
          A_ub = [[2, 1], [1, 1], [1, 0]]
          b_ub = [10, 8, 4]
          assert_raises(NotImplementedError, linprog, c, A_ub=A_ub, b_ub=b_ub,
                        callback=cb, method=self.method)
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, method=self.method)
          _assert_success(res, desired_fun=-18.0, desired_x=[2, 6])
  
      @pytest.mark.parametrize("options",
                               [{"maxiter": -1},
                                {"disp": -1},
                                {"presolve": -1},
                                {"time_limit": -1},
                                {"dual_feasibility_tolerance": -1},
                                {"primal_feasibility_tolerance": -1},
                                {"ipm_optimality_tolerance": -1},
                                {"simplex_dual_edge_weight_strategy": "ekki"},
                                ])
      def test_invalid_option_values(self, options):
          def f(options):
              linprog(1, method=self.method, options=options)
          options.update(self.options)
          assert_warns(OptimizeWarning, f, options=options)
  
      def test_crossover(self):
          c = np.array([1, 1]) * -1  # maximize
          A_ub = np.array([[1, 1]])
          b_ub = [1]
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq=b_eq,
                        bounds=bounds, method=self.method, options=self.options)
          # there should be nonzero crossover iterations for IPM (only)
          assert_equal(res.crossover_nit == 0, self.method != "highs-ipm")
  
      def test_marginals(self):
          # Ensure lagrange multipliers are correct by comparing the derivative
          # w.r.t. b_ub/b_eq/ub/lb to the reported duals.
          c, A_ub, b_ub, A_eq, b_eq, bounds = very_random_gen(seed=0)
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq=b_eq,
                        bounds=bounds, method=self.method, options=self.options)
          lb, ub = bounds.T
  
          # sensitivity w.r.t. b_ub
          def f_bub(x):
              return linprog(c, A_ub, x, A_eq, b_eq, bounds,
                             method=self.method).fun
  
          dfdbub = approx_derivative(f_bub, b_ub, method='3-point', f0=res.fun)
          assert_allclose(res.ineqlin.marginals, dfdbub)
  
          # sensitivity w.r.t. b_eq
          def f_beq(x):
              return linprog(c, A_ub, b_ub, A_eq, x, bounds,
                             method=self.method).fun
  
          dfdbeq = approx_derivative(f_beq, b_eq, method='3-point', f0=res.fun)
          assert_allclose(res.eqlin.marginals, dfdbeq)
  
          # sensitivity w.r.t. lb
          def f_lb(x):
              bounds = np.array([x, ub]).T
              return linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                             method=self.method).fun
  
          with np.errstate(invalid='ignore'):
              # approx_derivative has trouble where lb is infinite
              dfdlb = approx_derivative(f_lb, lb, method='3-point', f0=res.fun)
              dfdlb[~np.isfinite(lb)] = 0
  
          assert_allclose(res.lower.marginals, dfdlb)
  
          # sensitivity w.r.t. ub
          def f_ub(x):
              bounds = np.array([lb, x]).T
              return linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                             method=self.method).fun
  
          with np.errstate(invalid='ignore'):
              dfdub = approx_derivative(f_ub, ub, method='3-point', f0=res.fun)
              dfdub[~np.isfinite(ub)] = 0
  
          assert_allclose(res.upper.marginals, dfdub)
  
      def test_dual_feasibility(self):
          # Ensure solution is dual feasible using marginals
          c, A_ub, b_ub, A_eq, b_eq, bounds = very_random_gen(seed=42)
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq=b_eq,
                        bounds=bounds, method=self.method, options=self.options)
  
          # KKT dual feasibility equation from Theorem 1 from
          # http://www.personal.psu.edu/cxg286/LPKKT.pdf
          resid = (-c + A_ub.T @ res.ineqlin.marginals +
                   A_eq.T @ res.eqlin.marginals +
                   res.upper.marginals +
                   res.lower.marginals)
          assert_allclose(resid, 0, atol=1e-12)
  
      def test_complementary_slackness(self):
          # Ensure that the complementary slackness condition is satisfied.
          c, A_ub, b_ub, A_eq, b_eq, bounds = very_random_gen(seed=42)
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, A_eq=A_eq, b_eq=b_eq,
                        bounds=bounds, method=self.method, options=self.options)
  
          # KKT complementary slackness equation from Theorem 1 from
          # http://www.personal.psu.edu/cxg286/LPKKT.pdf modified for
          # non-zero RHS
          assert np.allclose(res.ineqlin.marginals @ (b_ub - A_ub @ res.x), 0)
  
  
  ################################
  # Simplex Option-Specific Tests#
  ################################
  
  
  class TestLinprogSimplexDefault(LinprogSimplexTests):
  
      def setup_method(self):
          self.options = {}
  
      def test_bug_5400(self):
          pytest.skip("Simplex fails on this problem.")
  
      def test_bug_7237_low_tol(self):
          # Fails if the tolerance is too strict. Here, we test that
          # even if the solution is wrong, the appropriate error is raised.
          pytest.skip("Simplex fails on this problem.")
  
      def test_bug_8174_low_tol(self):
          # Fails if the tolerance is too strict. Here, we test that
          # even if the solution is wrong, the appropriate warning is issued.
          self.options.update({'tol': 1e-12})
          with pytest.warns(OptimizeWarning):
              super().test_bug_8174()
  
  
  class TestLinprogSimplexBland(LinprogSimplexTests):
  
      def setup_method(self):
          self.options = {'bland': True}
  
      def test_bug_5400(self):
          pytest.skip("Simplex fails on this problem.")
  
      def test_bug_8174_low_tol(self):
          # Fails if the tolerance is too strict. Here, we test that
          # even if the solution is wrong, the appropriate error is raised.
          self.options.update({'tol': 1e-12})
          with pytest.raises(AssertionError):
              with pytest.warns(OptimizeWarning):
                  super().test_bug_8174()
  
  
  class TestLinprogSimplexNoPresolve(LinprogSimplexTests):
  
      def setup_method(self):
          self.options = {'presolve': False}
  
      is_32_bit = np.intp(0).itemsize < 8
      is_linux = sys.platform.startswith('linux')
  
      @pytest.mark.xfail(
          condition=is_32_bit and is_linux,
          reason='Fails with warning on 32-bit linux')
      def test_bug_5400(self):
          super().test_bug_5400()
  
      def test_bug_6139_low_tol(self):
          # Linprog(method='simplex') fails to find a basic feasible solution
          # if phase 1 pseudo-objective function is outside the provided tol.
          # https://github.com/scipy/scipy/issues/6139
          # Without ``presolve`` eliminating such rows the result is incorrect.
          self.options.update({'tol': 1e-12})
          with pytest.raises(AssertionError, match='linprog status 4'):
              return super().test_bug_6139()
  
      def test_bug_7237_low_tol(self):
          pytest.skip("Simplex fails on this problem.")
  
      def test_bug_8174_low_tol(self):
          # Fails if the tolerance is too strict. Here, we test that
          # even if the solution is wrong, the appropriate warning is issued.
          self.options.update({'tol': 1e-12})
          with pytest.warns(OptimizeWarning):
              super().test_bug_8174()
  
      def test_unbounded_no_nontrivial_constraints_1(self):
          pytest.skip("Tests behavior specific to presolve")
  
      def test_unbounded_no_nontrivial_constraints_2(self):
          pytest.skip("Tests behavior specific to presolve")
  
  
  #######################################
  # Interior-Point Option-Specific Tests#
  #######################################
  
  
  class TestLinprogIPDense(LinprogIPTests):
      options = {"sparse": False}
  
  
  if has_cholmod:
      class TestLinprogIPSparseCholmod(LinprogIPTests):
          options = {"sparse": True, "cholesky": True}
  
  
  if has_umfpack:
      class TestLinprogIPSparseUmfpack(LinprogIPTests):
          options = {"sparse": True, "cholesky": False}
  
          def test_bug_10466(self):
              pytest.skip("Autoscale doesn't fix everything, and that's OK.")
  
          def test_network_flow_limited_capacity(self):
              pytest.skip("Failing due to numerical issues on some platforms.")
  
  
  class TestLinprogIPSparse(LinprogIPTests):
      options = {"sparse": True, "cholesky": False, "sym_pos": False}
  
      @pytest.mark.xfail_on_32bit("This test is sensitive to machine epsilon level "
                                  "perturbations in linear system solution in "
                                  "_linprog_ip._sym_solve.")
      def test_bug_6139(self):
          super().test_bug_6139()
  
      @pytest.mark.xfail(reason='Fails with ATLAS, see gh-7877')
      def test_bug_6690(self):
          # Test defined in base class, but can't mark as xfail there
          super().test_bug_6690()
  
      def test_magic_square_sparse_no_presolve(self):
          # test linprog with a problem with a rank-deficient A_eq matrix
          A_eq, b_eq, c, N = magic_square(3)
          bounds = (0, 1)
  
          with suppress_warnings() as sup:
              if has_umfpack:
                  sup.filter(UmfpackWarning)
              sup.filter(MatrixRankWarning, "Matrix is exactly singular")
              sup.filter(OptimizeWarning, "Solving system with option...")
  
              o = {key: self.options[key] for key in self.options}
              o["presolve"] = False
  
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options=o)
          _assert_success(res, desired_fun=1.730550597)
  
      def test_sparse_solve_options(self):
          # checking that problem is solved with all column permutation options
          A_eq, b_eq, c, N = magic_square(3)
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              sup.filter(OptimizeWarning, "Invalid permc_spec option")
              o = {key: self.options[key] for key in self.options}
              permc_specs = ('NATURAL', 'MMD_ATA', 'MMD_AT_PLUS_A',
                             'COLAMD', 'ekki-ekki-ekki')
              # 'ekki-ekki-ekki' raises warning about invalid permc_spec option
              # and uses default
              for permc_spec in permc_specs:
                  o["permc_spec"] = permc_spec
                  res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                                method=self.method, options=o)
                  _assert_success(res, desired_fun=1.730550597)
  
  
  class TestLinprogIPSparsePresolve(LinprogIPTests):
      options = {"sparse": True, "_sparse_presolve": True}
  
      @pytest.mark.xfail_on_32bit("This test is sensitive to machine epsilon level "
                                  "perturbations in linear system solution in "
                                  "_linprog_ip._sym_solve.")
      def test_bug_6139(self):
          super().test_bug_6139()
  
      def test_enzo_example_c_with_infeasibility(self):
          pytest.skip('_sparse_presolve=True incompatible with presolve=False')
  
      @pytest.mark.xfail(reason='Fails with ATLAS, see gh-7877')
      def test_bug_6690(self):
          # Test defined in base class, but can't mark as xfail there
          super().test_bug_6690()
  
  
  class TestLinprogIPSpecific:
      method = "interior-point"
      # the following tests don't need to be performed separately for
      # sparse presolve, sparse after presolve, and dense
  
      def test_solver_select(self):
          # check that default solver is selected as expected
          if has_cholmod:
              options = {'sparse': True, 'cholesky': True}
          elif has_umfpack:
              options = {'sparse': True, 'cholesky': False}
          else:
              options = {'sparse': True, 'cholesky': False, 'sym_pos': False}
          A, b, c = lpgen_2d(20, 20)
          res1 = linprog(c, A_ub=A, b_ub=b, method=self.method, options=options)
          res2 = linprog(c, A_ub=A, b_ub=b, method=self.method)  # default solver
          assert_allclose(res1.fun, res2.fun,
                          err_msg="linprog default solver unexpected result",
                          rtol=1e-15, atol=1e-15)
  
      def test_unbounded_below_no_presolve_original(self):
          # formerly caused segfault in TravisCI w/ "cholesky":True
          c = [-1]
          bounds = [(None, 1)]
          res = linprog(c=c, bounds=bounds,
                        method=self.method,
                        options={"presolve": False, "cholesky": True})
          _assert_success(res, desired_fun=-1)
  
      def test_cholesky(self):
          # use cholesky factorization and triangular solves
          A, b, c = lpgen_2d(20, 20)
          res = linprog(c, A_ub=A, b_ub=b, method=self.method,
                        options={"cholesky": True})  # only for dense
          _assert_success(res, desired_fun=-64.049494229)
  
      def test_alternate_initial_point(self):
          # use "improved" initial point
          A, b, c = lpgen_2d(20, 20)
          with suppress_warnings() as sup:
              sup.filter(RuntimeWarning, "scipy.linalg.solve\nIll...")
              sup.filter(OptimizeWarning, "Solving system with option...")
              sup.filter(LinAlgWarning, "Ill-conditioned matrix...")
              res = linprog(c, A_ub=A, b_ub=b, method=self.method,
                            options={"ip": True, "disp": True})
              # ip code is independent of sparse/dense
          _assert_success(res, desired_fun=-64.049494229)
  
      def test_bug_8664(self):
          # interior-point has trouble with this when presolve is off
          c = [4]
          A_ub = [[2], [5]]
          b_ub = [4, 4]
          A_eq = [[0], [-8], [9]]
          b_eq = [3, 2, 10]
          with suppress_warnings() as sup:
              sup.filter(RuntimeWarning)
              sup.filter(OptimizeWarning, "Solving system with option...")
              res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                            method=self.method, options={"presolve": False})
          assert_(not res.success, "Incorrectly reported success")
  
  
  ########################################
  # Revised Simplex Option-Specific Tests#
  ########################################
  
  
  class TestLinprogRSCommon(LinprogRSTests):
      options = {}
  
      def test_cyclic_bland(self):
          pytest.skip("Intermittent failure acceptable.")
  
      def test_nontrivial_problem_with_guess(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=x_star)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
          assert_equal(res.nit, 0)
  
      def test_nontrivial_problem_with_unbounded_variables(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          bounds = [(None, None), (None, None), (0, None), (None, None)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=x_star)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
          assert_equal(res.nit, 0)
  
      def test_nontrivial_problem_with_bounded_variables(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          bounds = [(None, 1), (1, None), (0, None), (.4, .6)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=x_star)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
          assert_equal(res.nit, 0)
  
      def test_nontrivial_problem_with_negative_unbounded_variable(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          b_eq = [4]
          x_star = np.array([-219/385, 582/385, 0, 4/10])
          f_star = 3951/385
          bounds = [(None, None), (1, None), (0, None), (.4, .6)]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=x_star)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
          assert_equal(res.nit, 0)
  
      def test_nontrivial_problem_with_bad_guess(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          bad_guess = [1, 2, 3, .5]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=bad_guess)
          assert_equal(res.status, 6)
  
      def test_redundant_constraints_with_guess(self):
          A, b, c, N = magic_square(3)
          p = np.random.rand(*c.shape)
          with suppress_warnings() as sup:
              sup.filter(OptimizeWarning, "A_eq does not appear...")
              sup.filter(RuntimeWarning, "invalid value encountered")
              sup.filter(LinAlgWarning)
              res = linprog(c, A_eq=A, b_eq=b, method=self.method)
              res2 = linprog(c, A_eq=A, b_eq=b, method=self.method, x0=res.x)
              res3 = linprog(c + p, A_eq=A, b_eq=b, method=self.method, x0=res.x)
          _assert_success(res2, desired_fun=1.730550597)
          assert_equal(res2.nit, 0)
          _assert_success(res3)
          assert_(res3.nit < res.nit)  # hot start reduces iterations
  
  
  class TestLinprogRSBland(LinprogRSTests):
      options = {"pivot": "bland"}
  
  
  ############################################
  # HiGHS-Simplex-Dual Option-Specific Tests #
  ############################################
  
  
  class TestLinprogHiGHSSimplexDual(LinprogHiGHSTests):
      method = "highs-ds"
      options = {}
  
      def test_lad_regression(self):
          '''The scaled model should be optimal but unscaled model infeasible.'''
          c, A_ub, b_ub, bnds = l1_regression_prob()
          res = linprog(c, A_ub=A_ub, b_ub=b_ub, bounds=bnds,
                        method=self.method, options=self.options)
          assert_equal(res.status, 4)
          assert_('An optimal solution to the scaled '
                  'model was found but' in res.message)
          assert_(res.x is not None)
          assert_(np.all(res.slack > -1e-6))
          assert_(np.all(res.x <= [np.inf if u is None else u for l, u in bnds]))
          assert_(np.all(res.x >= [-np.inf if l is None else l for l, u in bnds]))
  
  
  ###################################
  # HiGHS-IPM Option-Specific Tests #
  ###################################
  
  
  class TestLinprogHiGHSIPM(LinprogHiGHSTests):
      method = "highs-ipm"
      options = {}
  
  
  ###########################
  # Autoscale-Specific Tests#
  ###########################
  
  
  class AutoscaleTests:
      options = {"autoscale": True}
  
      test_bug_6139 = LinprogCommonTests.test_bug_6139
      test_bug_6690 = LinprogCommonTests.test_bug_6690
      test_bug_7237 = LinprogCommonTests.test_bug_7237
  
  
  class TestAutoscaleIP(AutoscaleTests):
      method = "interior-point"
  
      def test_bug_6139(self):
          self.options['tol'] = 1e-10
          return AutoscaleTests.test_bug_6139(self)
  
  
  class TestAutoscaleSimplex(AutoscaleTests):
      method = "simplex"
  
  
  class TestAutoscaleRS(AutoscaleTests):
      method = "revised simplex"
  
      def test_nontrivial_problem_with_guess(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=x_star)
          _assert_success(res, desired_fun=f_star, desired_x=x_star)
          assert_equal(res.nit, 0)
  
      def test_nontrivial_problem_with_bad_guess(self):
          c, A_ub, b_ub, A_eq, b_eq, x_star, f_star = nontrivial_problem()
          bad_guess = [1, 2, 3, .5]
          res = linprog(c, A_ub, b_ub, A_eq, b_eq, bounds,
                        method=self.method, options=self.options, x0=bad_guess)
          assert_equal(res.status, 6)
  
  
  ###########################
  # Redundancy Removal Tests#
  ###########################
  
  
  class RRTests:
      method = "interior-point"
      LCT = LinprogCommonTests
      # these are a few of the existing tests that have redundancy
      test_RR_infeasibility = LCT.test_remove_redundancy_infeasibility
      test_bug_10349 = LCT.test_bug_10349
      test_bug_7044 = LCT.test_bug_7044
      test_NFLC = LCT.test_network_flow_limited_capacity
      test_enzo_example_b = LCT.test_enzo_example_b
  
  
  class TestRRSVD(RRTests):
      options = {"rr_method": "SVD"}
  
  
  class TestRRPivot(RRTests):
      options = {"rr_method": "pivot"}
  
  
  class TestRRID(RRTests):
      options = {"rr_method": "ID"}
  