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rational_interpolant_pole_matching.py
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Tue, Apr 30, 23:44

rational_interpolant_pole_matching.py
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# Copyright (C) 2018 by the RROMPy authors
#
# This file is part of RROMPy.
#
# RROMPy is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# RROMPy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with RROMPy. If not, see <http://www.gnu.org/licenses/>.
#
from copy import deepcopy as copy
import numpy as np
from rrompy.reduction_methods.pivoting.rational_interpolant_pivoted import \
RationalInterpolantPivoted
from .generic_pole_matching_approximant import GenericPoleMatchingApproximant
from rrompy.utilities.poly_fitting.polynomial import (
PolynomialInterpolator as PI)
from rrompy.reduction_methods.trained_model import (TrainedModelPivotedData,
TrainedModelPoleMatchingRational as tModel)
from rrompy.utilities.base import verbosityManager as vbMng
from rrompy.utilities.exception_manager import RROMPyAssert
__all__ = ['RationalInterpolantPoleMatching']
class RationalInterpolantPoleMatching(GenericPoleMatchingApproximant,
RationalInterpolantPivoted):
"""
ROM pivoted rational interpolant computation for parametric problems with
pole matching.
Args:
HFEngine: HF problem solver.
mu0(optional): Default parameter. Defaults to 0.
directionPivot(optional): Pivot components. Defaults to [0].
approxParameters(optional): Dictionary containing values for main
parameters of approximant. Recognized keys are:
- 'POD': whether to compute POD of snapshots; defaults to True;
- 'matchingWeight': weight for pole matching optimization; defaults
to 1;
- 'cutOffTolerance': tolerance for ignoring parasitic poles;
defaults to np.inf;
- 'cutOffType': rule for tolerance computation for parasitic poles;
defaults to 'MAGNITUDE';
- 'S': total number of pivot samples current approximant relies
upon;
- 'samplerPivot': pivot sample point generator;
- 'SMarginal': total number of marginal samples current approximant
relies upon;
- 'samplerMarginal': marginal sample point generator;
- 'polybasisPivot': type of polynomial basis for pivot
interpolation; allowed values include 'MONOMIAL', 'CHEBYSHEV'
and 'LEGENDRE'; defaults to 'MONOMIAL';
- 'polybasisMarginal': type of polynomial basis for marginal
interpolation; allowed values include 'MONOMIAL', 'CHEBYSHEV'
and 'LEGENDRE'; defaults to 'MONOMIAL';
- 'E': number of derivatives used to compute interpolant; defaults
to 0;
- 'M': degree of rational interpolant numerator; defaults to 0;
- 'N': degree of rational interpolant denominator; defaults to 0;
- 'MMarginal': degree of marginal interpolant; defaults to 0;
- 'radialBasisPivot': radial basis family for pivot numerator;
defaults to 0, i.e. no radial basis;
- 'radialBasisMarginal': radial basis family for marginal
interpolant; defaults to 0, i.e. no radial basis;
- 'radialBasisWeightsPivot': radial basis weights for pivot
numerator; defaults to 0, i.e. identity;
- 'radialBasisWeightsMarginal': radial basis weights for marginal
interpolant; defaults to 0, i.e. identity;
- 'interpRcondPivot': tolerance for pivot interpolation; defaults
to None;
- 'interpRcondMarginal': tolerance for marginal interpolation;
defaults to None;
- 'robustTol': tolerance for robust rational denominator
management; defaults to 0.
Defaults to empty dict.
homogeneized(optional): Whether to homogeneize Dirichlet BCs. Defaults
to False.
verbosity(optional): Verbosity level. Defaults to 10.
Attributes:
HFEngine: HF problem solver.
mu0: Default parameter.
directionPivot: Pivot components.
mus: Array of snapshot parameters.
musPivot: Array of pivot snapshot parameters.
musMarginal: Array of marginal snapshot parameters.
homogeneized: Whether to homogeneize Dirichlet BCs.
approxParameters: Dictionary containing values for main parameters of
approximant. Recognized keys are in parameterList.
parameterListSoft: Recognized keys of soft approximant parameters:
- 'POD': whether to compute POD of snapshots;
- 'matchingWeight': weight for pole matching optimization;
- 'cutOffTolerance': tolerance for ignoring parasitic poles;
- 'cutOffType': rule for tolerance computation for parasitic poles;
- 'polybasisPivot': type of polynomial basis for pivot
interpolation;
- 'polybasisMarginal': type of polynomial basis for marginal
interpolation;
- 'E': number of derivatives used to compute interpolant;
- 'M': degree of rational interpolant numerator;
- 'N': degree of rational interpolant denominator;
- 'MMarginal': degree of marginal interpolant;
- 'radialBasisPivot': radial basis family for pivot numerator;
- 'radialBasisMarginal': radial basis family for marginal
interpolant;
- 'radialBasisWeightsPivot': radial basis weights for pivot
numerator;
- 'radialBasisWeightsMarginal': radial basis weights for marginal
interpolant;
- 'interpRcondPivot': tolerance for pivot interpolation;
- 'interpRcondMarginal': tolerance for marginal interpolation;
- 'robustTol': tolerance for robust rational denominator
management.
parameterListCritical: Recognized keys of critical approximant
parameters:
- 'S': total number of pivot samples current approximant relies
upon;
- 'samplerPivot': pivot sample point generator;
- 'SMarginal': total number of marginal samples current approximant
relies upon;
- 'samplerMarginal': marginal sample point generator.
POD: Whether to compute POD of snapshots.
matchingWeight: Weight for pole matching optimization.
cutOffTolerance: Tolerance for ignoring parasitic poles.
cutOffType: Rule for tolerance computation for parasitic poles.
S: Total number of pivot samples current approximant relies upon.
sampler: Pivot sample point generator.
polybasisPivot: Type of polynomial basis for pivot interpolation.
polybasisMarginal: Type of polynomial basis for marginal interpolation.
M: Numerator degree of approximant.
N: Denominator degree of approximant.
MMarginal: Degree of marginal interpolant.
radialBasisPivot: Radial basis family for pivot numerator.
radialBasisMarginal: Radial basis family for marginal interpolant.
radialBasisWeightsPivot: Radial basis weights for pivot numerator.
radialBasisWeightsMarginal: Radial basis weights for marginal
interpolant.
interpRcondPivot: Tolerance for pivot interpolation.
interpRcondMarginal: Tolerance for marginal interpolation.
robustTol: Tolerance for robust rational denominator management.
E: Complete derivative depth level of S.
muBoundsPivot: list of bounds for pivot parameter values.
muBoundsMarginal: list of bounds for marginal parameter values.
samplingEngine: Sampling engine.
uHF: High fidelity solution(s) with parameter(s) lastSolvedHF as
sampleList.
lastSolvedHF: Parameter(s) corresponding to last computed high fidelity
solution(s) as parameterList.
uApproxReduced: Reduced approximate solution(s) with parameter(s)
lastSolvedApprox as sampleList.
lastSolvedApproxReduced: Parameter(s) corresponding to last computed
reduced approximate solution(s) as parameterList.
uApprox: Approximate solution(s) with parameter(s) lastSolvedApprox as
sampleList.
lastSolvedApprox: Parameter(s) corresponding to last computed
approximate solution(s) as parameterList.
Q: Numpy 1D vector containing complex coefficients of approximant
denominator.
P: Numpy 2D vector whose columns are FE dofs of coefficients of
approximant numerator.
"""
def setupApprox(self):
"""
Compute rational interpolant.
SVD-based robust eigenvalue management.
"""
if self.checkComputedApprox():
return
RROMPyAssert(self._mode, message = "Cannot setup approximant.")
vbMng(self, "INIT", "Setting up {}.". format(self.name()), 5)
self.computeScaleFactor()
self.computeSnapshots()
if self.trainedModel is None:
self.trainedModel = tModel()
self.trainedModel.verbosity = self.verbosity
self.trainedModel.timestamp = self.timestamp
data = TrainedModelPivotedData(self.trainedModel.name(), self.mu0,
self.samplingEngine.samplesCoalesced,
self.scaleFactor,
self.HFEngine.rescalingExp,
self.directionPivot)
data.musPivot = copy(self.musPivot)
data.musMarginal = copy(self.musMarginal)
self.trainedModel.data = data
else:
self.trainedModel = self.trainedModel
self.trainedModel.data.projMat = copy(
self.samplingEngine.samplesCoalesced)
self.trainedModel.data.marginalInterp = self._setupMarginalInterp()
if self.N > 0:
Qs = self._setupDenominator()
else:
Q = PI()
Q.npar = self.musPivot.shape[1]
Q.coeffs = np.ones(tuple([1] * Q.npar), dtype = np.complex)
Q.polybasis = self.polybasisPivot
Qs = [Q for _ in range(len(self.musMarginal))]
self.trainedModel.data._temporary = True
self.trainedModel.data.Qs = Qs
self.trainedModel.data.Ps = self._setupNumerator()
vbMng(self, "INIT", "Matching poles.", 10)
self.trainedModel.initializeFromRational(self.HFEngine,
self.matchingWeight, self.POD)
vbMng(self, "DEL", "Done matching poles.", 10)
if not np.isinf(self.cutOffTolerance):
vbMng(self, "INIT", "Recompressing by cut-off.", 10)
msg = self.trainedModel.recompressByCutOff([-1., 1.],
self.cutOffTolerance,
self.cutOffType)
vbMng(self, "DEL", "Done recompressing." + msg, 10)
self.trainedModel.data.approxParameters = copy(self.approxParameters)
vbMng(self, "DEL", "Done setting up approximant.", 5)

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