class_docstr: Check the Broyden methods for a few test problems.
  
  broyden1, broyden2, and newton_krylov must succeed for
  all functions. Some of the others don't -- tests in KNOWN_BAD are skipped.
class_docstr_tok: ["Check","the","Broyden","methods","for","a","few","test","problems",".","broyden1",",","broyden2",",","and","newton_krylov","must","succeed","for","all","functions",".","Some","of","the","others","do","n't","--","tests","in","KNOWN_BAD","are","skipped","."]
code: def test_problem_nonlin(self):
      for f in [F, F2, F2_lucky, F3, F4_powell, F5, F6]:
          for func in SOLVERS.values():
              if func in f.KNOWN_BAD.values():
                  if func in MUST_WORK.values():
                      self._check_func_fail(f, func)
                  continue
              self._check_nonlin_func(f, func)
  
imports: from __future__ import division, print_function, absolute_import
  from numpy.testing import assert_
  import pytest
  from scipy._lib.six import xrange
  from scipy.optimize import nonlin, root
  from numpy import diag, dot
  from numpy.linalg import inv
  import numpy
  from .test_minpack import pressure_network
label_desc: Use image node_id 4 for calling the TestNonlin obj's underlying member method code with example usage: obj.test_problem_nonlin() without return types