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 _check_root(self, f, method, f_tol=1e-2):
      res = root(
          f,
          f.xin,
          method=method,
          options={"ftol": f_tol, "maxiter": 200, "disp": 0},
      )
      assert_(np.absolute(res.fun).max() < f_tol)
  
imports: from numpy.testing import assert_
  import pytest
  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 2 for calling the TestNonlin obj's underlying member method code with example usage: obj._check_root(f, method, f_tol) without return types