OpenMDAO 单数入口答案

【问题标题】：OpenMDAO Singular EntryOpenMDAO 单数入口
【发布时间】：2018-04-11 22:24:56
【问题描述】：

我正在尝试了解 OpenMDAO 错误消息

RuntimeError: Singular entry found in '' for column associated with state/residual 'x'.

和

RuntimeError: Singular entry found in '' for row associated with state/residual 'y'.

有人能解释一下吗？例如。运行代码时

from openmdao.api import Problem, Group, IndepVarComp, ImplicitComponent, ScipyOptimizeDriver, NewtonSolver, DirectSolver, view_model, view_connections


class Test1Comp(ImplicitComponent):

    def setup(self):
        self.add_input('x', 0.5)
        self.add_input('design_x', 1.0)
        self.add_output('z', val=0.0)
        self.add_output('obj')

        self.declare_partials(of='*', wrt='*', method='fd', form='central', step=1.0e-4)

    def apply_nonlinear(self, inputs, outputs, resids):
        x = inputs['x']
        design_x = inputs['design_x']
        z = outputs['z']

        resids['z'] = x*z + z - 4
        resids['obj'] = (z/5.833333 - design_x)**2


if __name__ == "__main__":

    prob = Problem()
    model = prob.model = Group()

    model.add_subsystem('p1', IndepVarComp('x', 0.5))
    model.add_subsystem('d1', IndepVarComp('design_x', 1.0))
    model.add_subsystem('comp', Test1Comp())

    model.connect('p1.x', 'comp.x')
    model.connect('d1.design_x', 'comp.design_x')

    prob.driver = ScipyOptimizeDriver()
    prob.driver.options["optimizer"] = 'SLSQP'
    model.add_design_var("d1.design_x", lower=0.5, upper=1.5)
    model.add_objective('comp.obj')

    model.nonlinear_solver = NewtonSolver()
    model.nonlinear_solver.options['iprint'] = 2
    model.nonlinear_solver.options['maxiter'] = 20
    model.linear_solver = DirectSolver()

    prob.setup()
    prob.run_model()
    print(prob['comp.z'])

我收到错误消息：

  File "C:\Scripts/mockup_component3.py", line 46, in <module>
    prob.run_model()
  File "C:\Python_32\lib\site-packages\openmdao\core\problem.py", line 315, in run_model
    return self.model.run_solve_nonlinear()
  File "C:\Python_32\lib\site-packages\openmdao\core\system.py", line 2960, in run_solve_nonlinear
    result = self._solve_nonlinear()
  File "C:\Python_32\lib\site-packages\openmdao\core\group.py", line 1420, in _solve_nonlinear
    result = self._nonlinear_solver.solve()
  File "C:\Python_32\lib\site-packages\openmdao\solvers\solver.py", line 602, in solve
    fail, abs_err, rel_err = self._run_iterator()
  File "C:\Python_32\lib\site-packages\openmdao\solvers\solver.py", line 349, in _run_iterator
    self._iter_execute()
  File "C:\Python_32\lib\site-packages\openmdao\solvers\nonlinear\newton.py", line 234, in _iter_execute
    system._linearize()
  File "C:\Python_32\lib\site-packages\openmdao\core\group.py", line 1562, in _linearize
    self._linear_solver._linearize()
  File "C:\Python_32\lib\site-packages\openmdao\solvers\linear\direct.py", line 199, in _linearize
    raise RuntimeError(format_singluar_error(err, system, mtx))
RuntimeError: Singular entry found in '' for column associated with state/residual 'comp.obj'.

通过在resids['obj'] 的等式中添加- outputs['obj']，我能够解决这个错误。但是我对这两个错误消息的含义仍然知之甚少。什么矩阵是奇异的？拥有是什么意思

1) 列的单数条目？

2) 一行的单数条目？

【问题讨论】：

标签： openmdao

【解决方案1】：

我意识到单数 row 的原因是我没有定义组件的偏导数。我通过将命令declare_partials 添加到顶级系统来解决此问题。回溯给了我矩阵与线性化有关的线索。

单数列的情况似乎与我在apply_nonlinear中有两个方程，但只有一个未知（z）有关。

【讨论】：