""" Base class for linear and nonlinear solvers."""
from __future__ import print_function
from openmdao.recorders.recording_manager import RecordingManager
from openmdao.util.options import OptionsDictionary
[docs]class SolverBase(object):
""" Common base class for Linear and Nonlinear solver. Should not be used
by users. Always inherit from `LinearSolver` or `NonlinearSolver`."""
def __init__(self):
self.iter_count = 0
self.options = OptionsDictionary()
desc = 'Set to 0 to disable printing, set to 1 to print the ' \
'residual to stdout each iteration, set to 2 to print ' \
'subiteration residuals as well.'
self.options.add_option('iprint', 0, values=[0, 1, 2], desc=desc)
self.recorders = RecordingManager()
self.local_meta = None
[docs] def setup(self, sub):
""" Solvers override to define post-setup initiailzation.
Args
----
sub: `System`
System that owns this solver.
"""
pass
[docs] def cleanup(self):
""" Clean up resources prior to exit. """
self.recorders.close()
[docs] def print_norm(self, solver_string, pathname, iteration, res, res0,
msg=None, indent=0, solver='NL'):
""" Prints out the norm of the residual in a neat readable format.
Args
----
solver_string: string
Unique string to identify your solver type (e.g., 'LN_GS' or
'NEWTON').
pathname: dict
Parent system pathname.
iteration: int
Current iteration number
res: float
Absolute residual value.
res0: float
Baseline initial residual for relative comparison.
msg: string, optional
Message that indicates convergence.
ident: int, optional
Additional indentation levels for subiterations.
solver: string, optional
Solver type if not LN or NL (mostly for line search operations.)
"""
if pathname=='':
name = 'root'
else:
name = 'root.' + pathname
# Find indentation level
level = pathname.count('.')
# No indentation for driver; top solver is no indentation.
level = level + indent
indent = ' ' * level
if msg is not None:
form = indent + '[%s] %s: %s %d | %s'
print(form % (name, solver, solver_string, iteration, msg))
return
form = indent + '[%s] %s: %s %d | %.9g %.9g'
print(form % (name, solver, solver_string, iteration, res, res/res0))
[docs] def print_all_convergence(self):
""" Turns on iprint for this solver and all subsolvers. Override if
your solver has subsolvers."""
self.options['iprint'] = 1
[docs] def generate_docstring(self):
"""
Generates a numpy-style docstring for a user-created System class.
Returns
-------
docstring : str
string that contains a basic numpy docstring.
"""
#start the docstring off
docstring = ' \"\"\"\n'
#Put options into docstring
firstTime = 1
for key, value in sorted(vars(self).items()):
if type(value)==OptionsDictionary:
if firstTime: #start of Options docstring
docstring += '\n Options\n -------\n'
firstTime = 0
docstring += value._generate_docstring(key)
#finish up docstring
docstring += '\n \"\"\"\n'
return docstring
[docs]class LinearSolver(SolverBase):
""" Base class for all linear solvers. Inherit from this class to create a
new custom linear solver.
Options
-------
options['iprint'] : int(0)
Set to 0 to disable printing, set to 1 to print the residual to stdout
each iteration, set to 2 to print subiteration residuals as well.
"""
[docs] def add_recorder(self, recorder):
"""Appends the given recorder to this solver's list of recorders.
Args
----
recorder: `BaseRecorder`
A recorder object.
"""
self.recorders.append(recorder)
[docs] def solve(self, rhs, system, mode):
""" Solves the linear system for the problem in self.system. The
full solution vector is returned. This function must be defined
when inheriting.
Args
----
rhs : ndarray
Array containing the right-hand side for the linear solve. Also
possibly a 2D array with multiple right-hand sides.
system : `System`
Parent `System` object.
mode : string
Derivative mode, can be 'fwd' or 'rev'.
Returns
-------
ndarray : Solution vector
"""
pass
[docs]class NonLinearSolver(SolverBase):
""" Base class for all nonlinear solvers. Inherit from this class to create a
new custom nonlinear solver.
Options
-------
options['iprint'] : int(0)
Set to 0 to disable printing, set to 1 to print the residual to stdout
each iteration, set to 2 to print subiteration residuals as well.
"""
[docs] def add_recorder(self, recorder):
"""Appends the given recorder to this solver's list of recorders.
Args
----
recorder: `BaseRecorder`
A recorder object.
"""
self.recorders.append(recorder)
[docs] def solve(self, params, unknowns, resids, system, metadata=None):
""" Drive all residuals in self.system and all subsystems to zero.
This includes all implicit components. This function must be defined
when inheriting.
Args
----
params : `VecWrapper`
`VecWrapper` containing parameters. (p)
unknowns : `VecWrapper`
`VecWrapper` containing outputs and states. (u)
resids : `VecWrapper`
`VecWrapper` containing residuals. (r)
system : `System`
Parent `System` object.
metadata : dict, optional
Dictionary containing execution metadata (e.g. iteration coordinate).
"""
pass
[docs]class LineSearch(SolverBase):
""" Base class for all linesearch subsolvers. Line search is used by
other solvers such as the Newton solver. Inherit from this class to
create a new custom line search.
Options
-------
options['iprint'] : int(0)
Set to 0 to disable printing, set to 1 to print the residual to stdout
each iteration, set to 2 to print subiteration residuals as well.
"""
[docs] def solve(self, params, unknowns, resids, system, solver, alpha, fnorm,
fnorm0, metadata=None):
""" Take the gradient calculated by the parent solver and figure out
how far to go.
Args
----
params : `VecWrapper`
`VecWrapper` containing parameters. (p)
unknowns : `VecWrapper`
`VecWrapper` containing outputs and states. (u)
resids : `VecWrapper`
`VecWrapper` containing residuals. (r)
system : `System`
Parent `System` object.
metadata : dict, optional
Dictionary containing execution metadata (e.g. iteration coordinate).
solver : `Solver`
Parent solver instance.
alpha : float
Initial over-relaxation factor as used in parent solver.
fnorm : float
Initial norm of the residual for absolute tolerance check.
fnorm0 : float
Initial norm of the residual for relative tolerance check.
"""
pass
