Page MenuHomec4science
Files F60192563

rational_pade.py
No OneTemporary
Actions

File Metadata

Created
Sun, Apr 28, 04:52

rational_pade.py
View Options

# 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.base import checkRobustTolerance
from .rational_interpolant import RationalInterpolant
from rrompy.utilities.poly_fitting.polynomial import (
polybases as ppb, polyfitname,
polyvander as pvP, polyvanderTotal as pvTP,
polyTimesTable, vanderInvTable,
PolynomialInterpolator as PI)
from rrompy.utilities.poly_fitting.radial_basis import (polybases as rbpb,
RadialBasisInterpolator as RBI)
from rrompy.utilities.poly_fitting.moving_least_squares import (
MovingLeastSquaresInterpolator as MLSI)
from rrompy.utilities.base.types import Np2D, Tuple, List
from rrompy.utilities.base import verbosityManager as vbMng
from rrompy.utilities.numerical import customPInv, dot
from rrompy.utilities.numerical.degree import (fullDegreeN, totalDegreeN,
reduceDegreeN, degreeTotalToFull,
fullDegreeMaxMask, totalDegreeMaxMask)
from rrompy.utilities.exception_manager import (RROMPyException, RROMPyAssert,
RROMPyWarning)
__all__ = ['RationalPade']
class RationalPade(RationalInterpolant):
"""
ROM rational Pade' computation for parametric problems.
Args:
HFEngine: HF problem solver.
mu0(optional): Default parameter. 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;
- 'scaleFactorDer': scaling factors for derivative computation;
defaults to 'AUTO';
- 'S': total number of samples current approximant relies upon;
- 'sampler': sample point generator;
- 'polybasis': type of polynomial basis for interpolation; defaults
to 'MONOMIAL';
- 'M': degree of rational interpolant numerator; defaults to
'AUTO', i.e. maximum allowed;
- 'N': degree of rational interpolant denominator; defaults to
'AUTO', i.e. maximum allowed;
- 'polydegreetype': type of polynomial degree; defaults to 'TOTAL';
- 'radialDirectionalWeights': radial basis weights for interpolant
numerator; defaults to 1;
- 'nNearestNeighbor': mumber of nearest neighbors considered in
numerator if polybasis allows; defaults to -1;
- 'interpRcond': tolerance for interpolation; defaults to None;
- 'robustTol': tolerance for robust rational denominator
management; defaults to 0;
- 'correctorForce': whether corrector should forcefully delete bad
poles; defaults to False;
- 'correctorTol': tolerance for corrector step; defaults to 0.,
i.e. no bad poles;
- 'correctorMaxIter': maximum number of corrector iterations;
defaults to 1.
Defaults to empty dict.
approx_state(optional): Whether to approximate state. Defaults to
False.
verbosity(optional): Verbosity level. Defaults to 10.
Attributes:
HFEngine: HF problem solver.
mu0: Default parameter.
mus: Array of snapshot parameters.
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;
- 'scaleFactorDer': scaling factors for derivative computation;
- 'polybasis': type of polynomial basis for interpolation;
- 'M': degree of rational interpolant numerator;
- 'N': degree of rational interpolant denominator;
- 'polydegreetype': type of polynomial degree;
- 'radialDirectionalWeights': radial basis weights for interpolant
numerator;
- 'nNearestNeighbor': mumber of nearest neighbors considered in
numerator if polybasis allows;
- 'interpRcond': tolerance for interpolation via numpy.polyfit;
- 'robustTol': tolerance for robust rational denominator
management;
- 'correctorForce': whether corrector should forcefully delete bad
poles;
- 'correctorTol': tolerance for corrector step;
- 'correctorMaxIter': maximum number of corrector iterations.
parameterListCritical: Recognized keys of critical approximant
parameters:
- 'S': total number of samples current approximant relies upon;
- 'sampler': sample point generator.
approx_state: Whether to approximate state.
verbosity: Verbosity level.
POD: Whether to compute POD of snapshots.
scaleFactorDer: Scaling factors for derivative computation.
S: Number of solution snapshots over which current approximant is
based upon.
sampler: Sample point generator.
polybasis: type of polynomial basis for interpolation.
M: Numerator degree of approximant.
N: Denominator degree of approximant.
polydegreetype: Type of polynomial degree.
radialDirectionalWeights: Radial basis weights for interpolant
numerator.
nNearestNeighbor: Number of nearest neighbors considered in numerator
if polybasis allows.
interpRcond: Tolerance for interpolation via numpy.polyfit.
robustTol: Tolerance for robust rational denominator management.
correctorForce: Whether corrector should forcefully delete bad poles.
correctorTol: Tolerance for corrector step.
correctorMaxIter: Maximum number of corrector iterations.
muBounds: list of bounds for 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 _setupInterpolationIndices(self):
"""Setup parameters for polyvander."""
super()._setupInterpolationIndices()
if len(self._musUniqueCN) > 1:
raise RROMPyException(("Cannot apply centered-like method with "
"more than one distinct sample point."))
def _setupDenominator(self):
"""Compute rational denominator."""
RROMPyAssert(self._mode, message = "Cannot setup denominator.")
vbMng(self, "INIT", "Starting computation of denominator.", 7)
cfun = totalDegreeN if self.polydegreetype == "TOTAL" else fullDegreeN
if hasattr(self, "_N_isauto"):
self._setNAuto()
else:
N = reduceDegreeN(self.N, self.S, self.npar, self.polydegreetype)
if N < self.N:
RROMPyWarning(("N too large compared to S. Reducing N by "
"{}").format(self.N - N))
self.N = N
while self.N > 0:
invD, fitinv = self._computeInterpolantInverseBlocks()
Seff = cfun(self.N, self.npar)
idxSamplesEff = list(range(self.S - Seff, self.S))
if self.POD:
ev, eV = self.findeveVGQR(
self.samplingEngine.RPOD[:, idxSamplesEff], invD)
else:
ev, eV = self.findeveVGExplicit(
self.samplingEngine.samples(idxSamplesEff), invD)
nevBad = checkRobustTolerance(ev, self.robustTol)
if nevBad <= 1: break
if self.catchInstability > 0:
raise RROMPyException(("Instability in denominator "
"computation: eigenproblem is poorly "
"conditioned."),
self.catchInstability == 1)
RROMPyWarning(("Smallest {} eigenvalues below tolerance. Reducing "
"N by 1.").format(nevBad))
self.N = self.N - 1
if self.N <= 0:
self.N = 0
eV = np.ones((1, 1))
q = PI()
q.npar = self.npar
q.polybasis = self.polybasis0
if self.polydegreetype == "TOTAL":
q.coeffs = degreeTotalToFull(tuple([self.N + 1] * self.npar),
self.npar, eV[:, 0])
else:
q.coeffs = eV[:, 0].reshape([self.N + 1] * self.npar)
vbMng(self, "DEL", "Done computing denominator.", 7)
return q, fitinv
def _setupNumerator(self):
"""Compute rational numerator."""
RROMPyAssert(self._mode, message = "Cannot setup numerator.")
vbMng(self, "INIT", "Starting computation of numerator.", 7)
self._setupInterpolationIndices()
Qevaldiag = polyTimesTable(self.trainedModel.data.Q, self._musUniqueCN,
self._reorder, self._derIdxs,
self.scaleFactorRel)
if self.POD:
Qevaldiag = Qevaldiag.dot(self.samplingEngine.RPOD.T)
if hasattr(self, "radialDirectionalWeights"):
rDW = copy(self.radialDirectionalWeights)
cfun = totalDegreeN if self.polydegreetype == "TOTAL" else fullDegreeN
if hasattr(self, "_M_isauto"):
self._setMAuto()
M = self.M
else:
M = reduceDegreeN(self.M, self.S, self.npar, self.polydegreetype)
if M < self.M:
RROMPyWarning(("M too large compared to S. Reducing M by "
"{}").format(self.M - M))
self.M = M
while (self.M >= 0 and (not hasattr(self, "radialDirectionalWeights")
or self.radialDirectionalWeights[0] <= rDW[0] * 2 ** 6)):
Seff = cfun(self.M, self.npar)
pParRest = [self.verbosity >= 5, self.polydegreetype == "TOTAL",
{"derIdxs": [self._derIdxs[0][: Seff]],
"reorder": self._reorder[: Seff],
"scl": self.scaleFactorRel}]
if self.polybasis in ppb:
p = PI()
else:
pParRest = [self.radialDirectionalWeights] + pParRest
pParRest[-1]["nNearestNeighbor"] = self.nNearestNeighbor
p = RBI() if self.polybasis in rbpb else MLSI()
if self.polybasis in ppb + rbpb:
pParRest += [{"rcond": self.interpRcond}]
wellCond, msg = p.setupByInterpolation(self._musUniqueCN,
Qevaldiag[: Seff, : Seff],
self.M, self.polybasis,
*pParRest)
vbMng(self, "MAIN", msg, 5)
if wellCond: break
if self.catchInstability > 0:
raise RROMPyException(("Instability in numerator computation: "
"polyfit is poorly conditioned."),
self.catchInstability == 1)
if self.polybasis in ppb:
vbMng(self, "MAIN", ("Polyfit is poorly conditioned. Reducing "
"M by 1."), 10)
self.M = self.M - 1
else:
vbMng(self, "MAIN", ("Polyfit is poorly conditioned. "
"Multiplying radialDirectionalWeights "
"by 2."), 10)
for j in range(self.npar):
self._radialDirectionalWeights[j] *= 2.
if self.M < 0 or (hasattr(self, "radialDirectionalWeights")
and self.radialDirectionalWeights[0] > rDW[0] * 2 ** 6):
raise RROMPyException(("Instability in computation of numerator. "
"Aborting."))
if self.polybasis in ppb:
self.M = M
else:
self.radialDirectionalWeights = rDW
vbMng(self, "DEL", "Done computing numerator.", 7)
return p
def _computeInterpolantInverseBlocks(self) -> Tuple[List[Np2D], Np2D]:
"""
Compute inverse factors for minimal interpolant target functional.
"""
RROMPyAssert(self._mode, message = "Cannot solve eigenvalue problem.")
self._setupInterpolationIndices()
if self.polydegreetype == "TOTAL":
cfun, TEGen = totalDegreeN, pvTP
else:
cfun, TEGen = fullDegreeN, pvP
E = max(self.M, self.N)
while E >= 0:
Seff = cfun(E, self.npar)
TEGenPar = [self.polybasis0, [self._derIdxs[0][: Seff]],
self._reorder[: Seff], self.scaleFactorRel]
if self.polydegreetype == "TOTAL":
Eeff = E
idxsB = totalDegreeMaxMask(E, self.npar)
else: #if self.polydegreetype == "FULL":
Eeff = [E] * self.npar
idxsB = fullDegreeMaxMask(E, self.npar)
TE = TEGen(self._musUniqueCN, Eeff, *TEGenPar)
fitOut = customPInv(TE, rcond = self.interpRcond, full = True)
vbMng(self, "MAIN",
("Fitting {} samples with degree {} through {}... "
"Conditioning of pseudoinverse system: {:.4e}.").format(
TE.shape[0], E,
polyfitname(self.polybasis0),
fitOut[1][1][0] / fitOut[1][1][-1]),
5)
if fitOut[1][0] == TE.shape[1]:
fitinv = fitOut[0][idxsB, :]
break
if self.catchInstability > 0:
raise RROMPyException(("Instability in denominator "
"computation: polyfit is poorly "
"conditioned."),
self.catchInstability == 1)
EeqN = E == self.N
vbMng(self, "MAIN", ("Polyfit is poorly conditioned. Reducing E {}"
"by 1.").format("and N " * EeqN), 10)
if EeqN: self.N = self.N - 1
E -= 1
if self.N < 0:
raise RROMPyException(("Instability in computation of "
"denominator. Aborting."))
invD = vanderInvTable(fitinv, idxsB, self._reorder[: Seff],
[self._derIdxs[0][: Seff]])
if self.N == E:
TN = TE
else:
if self.polydegreetype == "TOTAL":
Neff = self.N
idxsB = totalDegreeMaxMask(self.N, self.npar)
else: #if self.polydegreetype == "FULL":
Neff = [self.N] * self.npar
idxsB = fullDegreeMaxMask(self.N, self.npar)
TN = TEGen(self._musUniqueCN, Neff, *TEGenPar)
for k in range(len(invD)): invD[k] = dot(invD[k], TN)
return invD, fitinv

Event Timeline

c4science · Help