code: def test_explicit(self):
      explicit_mod = Model(
          self.explicit_fcn,
          fjacb=self.explicit_fjb,
          fjacd=self.explicit_fjd,
          meta=dict(
              name="Sample Explicit Model", ref="ODRPACK UG, pg. 39"
          ),
      )
      explicit_dat = Data(
          [
              0.0,
              0.0,
              5.0,
              7.0,
              7.5,
              10.0,
              16.0,
              26.0,
              30.0,
              34.0,
              34.5,
              100.0,
          ],
          [
              1265.0,
              1263.6,
              1258.0,
              1254.0,
              1253.0,
              1249.8,
              1237.0,
              1218.0,
              1220.6,
              1213.8,
              1215.5,
              1212.0,
          ],
      )
      explicit_odr = ODR(
          explicit_dat,
          explicit_mod,
          beta0=[1500.0, -50.0, -0.1],
          ifixx=[0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0],
      )
      explicit_odr.set_job(deriv=2)
      explicit_odr.set_iprint(init=0, iter=0, final=0)
  
      out = explicit_odr.run()
      assert_array_almost_equal(
          out.beta,
          np.array(
              [
                  1.2646548050648876e03,
                  -5.4018409956678255e01,
                  -8.7849712165253724e-02,
              ]
          ),
      )
      assert_array_almost_equal(
          out.sd_beta,
          np.array(
              [
                  1.0349270280543437,
                  1.583997785262061,
                  0.0063321988657267,
              ]
          ),
      )
      assert_array_almost_equal(
          out.cov_beta,
          np.array(
              [
                  [
                      4.4949592379003039e-01,
                      -3.7421976890364739e-01,
                      -8.0978217468468912e-04,
                  ],
                  [
                      -3.7421976890364739e-01,
                      1.0529686462751804e00,
                      -1.9453521827942002e-03,
                  ],
                  [
                      -8.0978217468468912e-04,
                      -1.9453521827942002e-03,
                      1.6827336938454476e-05,
                  ],
              ]
          ),
      )
  
imports: import tempfile
  import shutil
  import os
  import numpy
  from numpy import pi
  from numpy.testing import assert_array_almost_equal, assert_equal, assert_warns
  import pytest
  from pytest import raises
  from scipy.odr import Data, Model, ODR, RealData, OdrStop, OdrWarning, multilinear, exponential, unilinear, quadratic, polynomial
label_desc: Use image node_id 7 for calling the TestODR obj's underlying member method code with example usage: obj.test_explicit() without return types