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rb_distributed.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 .generic_distributed_approximant import GenericDistributedApproximant
from rrompy.reduction_methods.trained_model import TrainedModelRB as tModel
from rrompy.reduction_methods.trained_model import TrainedModelData
from rrompy.reduction_methods.base.rb_utils import projectAffineDecomposition
from rrompy.utilities.base.types import (Np1D, Np2D, List, Tuple, DictAny,
HFEng, paramVal)
from rrompy.utilities.base import purgeDict, verbosityDepth
from rrompy.utilities.exception_manager import RROMPyWarning, RROMPyException
__all__ = ['RBDistributed']
class RBDistributed(GenericDistributedApproximant):
"""
ROM RB approximant 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:
- 'muBounds': list of bounds for parameter values; defaults to
[0, 1];
- 'S': total number of samples current approximant relies upon;
defaults to 2;
- 'sampler': sample point generator; defaults to uniform sampler on
muBounds;
- 'R': rank for Galerkin projection; defaults to S.
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.
mus: Array of snapshot parameters.
ws: Array of snapshot weigths (unused).
homogeneized: Whether to homogeneize Dirichlet BCs.
approxRadius: Dummy radius of approximant (i.e. distance from mu0 to
farthest sample point).
approxParameters: Dictionary containing values for main parameters of
approximant. Recognized keys are in parameterList.
parameterList: Recognized keys of approximant parameters:
- 'POD': whether to compute POD of snapshots;
- 'muBounds': list of bounds for parameter values;
- 'S': total number of samples current approximant relies upon;
- 'sampler': sample point generator;
- 'R': rank for Galerkin projection.
extraApproxParameters: List of approxParameters keys in addition to
mother class's.
POD: Whether to compute POD of snapshots.
muBounds: list of bounds for parameter values.
S: Number of solution snapshots over which current approximant is
based upon.
sampler: Sample point generator.
R: Rank for Galerkin projection.
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.
uAppReduced: Reduced approximate solution(s) with parameter(s)
lastSolvedApp as sampleList.
lastSolvedAppReduced: Parameter(s) corresponding to last computed
reduced approximate solution(s) as parameterList.
uApp: Approximate solution(s) with parameter(s) lastSolvedApp as
sampleList.
lastSolvedApp: Parameter(s) corresponding to last computed approximate
solution(s) as parameterList.
As: List of sparse matrices (in CSC format) representing coefficients
of linear system matrix wrt theta(mu).
bs: List of numpy vectors representing coefficients of linear system
RHS wrt theta(mu).
thetaAs: List of callables representing coefficients of linear system
matrix wrt mu.
thetabs: List of callables representing coefficients of linear system
RHS wrt mu.
ARBs: List of sparse matrices (in CSC format) representing coefficients
of compressed linear system matrix wrt theta(mu).
bRBs: List of numpy vectors representing coefficients of compressed
linear system RHS wrt theta(mu).
"""
def __init__(self, HFEngine:HFEng, mu0 : paramVal = None,
approxParameters : DictAny = {}, homogeneized : bool = False,
verbosity : int = 10, timestamp : bool = True):
self._preInit()
self._addParametersToList(["R"])
super().__init__(HFEngine = HFEngine, mu0 = mu0,
approxParameters = approxParameters,
homogeneized = homogeneized,
verbosity = verbosity, timestamp = timestamp)
if self.verbosity >= 10:
verbosityDepth("INIT", "Computing affine blocks of system.",
timestamp = self.timestamp)
self.As = self.HFEngine.affineLinearSystemA(self.mu0)
self.bs = self.HFEngine.affineLinearSystemb(self.mu0,
self.homogeneized)
if self.verbosity >= 10:
verbosityDepth("DEL", "Done computing affine blocks.",
timestamp = self.timestamp)
self._postInit()
@property
def approxParameters(self):
"""
Value of approximant parameters. Its assignment may change M, N and S.
"""
return self._approxParameters
@approxParameters.setter
def approxParameters(self, approxParams):
approxParameters = purgeDict(approxParams, self.parameterList,
dictname = self.name() + ".approxParameters",
baselevel = 1)
approxParametersCopy = purgeDict(approxParameters, ["R"], True, True,
baselevel = 1)
GenericDistributedApproximant.approxParameters.fset(self,
approxParametersCopy)
keyList = list(approxParameters.keys())
if "R" in keyList:
self.R = approxParameters["R"]
elif hasattr(self, "_R") and self._R is not None:
self.R = self.R
else:
self.R = self.S
@property
def R(self):
"""Value of R. Its assignment may change S."""
return self._R
@R.setter
def R(self, R):
if R < 0: raise RROMPyException("R must be non-negative.")
self._R = R
self._approxParameters["R"] = self.R
if hasattr(self, "_S") and self.S < self.R:
RROMPyWarning("Prescribed S is too small. Updating S to R.")
self.S = self.R
def setupApprox(self):
"""Compute RB projection matrix."""
if self.checkComputedApprox():
return
if self.verbosity >= 5:
verbosityDepth("INIT", "Setting up {}.". format(self.name()),
timestamp = self.timestamp)
self.computeSnapshots()
if self.verbosity >= 7:
verbosityDepth("INIT", "Computing projection matrix.",
timestamp = self.timestamp)
if self.POD:
U, _, _ = np.linalg.svd(self.samplingEngine.RPOD,
full_matrices = False)
pMat = self.samplingEngine.samples.dot(U[:, : self.R])
else:
pMat = self.samplingEngine.samples[: self.R]
if self.trainedModel is None:
self.trainedModel = tModel()
self.trainedModel.verbosity = self.verbosity
self.trainedModel.timestamp = self.timestamp
data = TrainedModelData(self.trainedModel.name(), self.mu0,
pMat, self.HFEngine.rescalingExp)
data.thetaAs = self.HFEngine.affineWeightsA(self.mu0)
data.thetabs = self.HFEngine.affineWeightsb(self.mu0,
self.homogeneized)
data.ARBs, data.bRBs = self.assembleReducedSystem(pMat)
data.mus = copy(self.mus)
self.trainedModel.data = data
else:
self.trainedModel = self.trainedModel
pMatOld = self.trainedModel.data.projMat
Sold = pMatOld.shape[1]
ARBs, bRBs = self.assembleReducedSystem(pMat[:, Sold :], pMatOld)
self.trainedModel.data.ARBs = ARBs
self.trainedModel.data.bRBs = bRBs
self.trainedModel.data.projMat = copy(pMat)
if self.verbosity >= 7:
verbosityDepth("DEL", "Done computing projection matrix.",
timestamp = self.timestamp)
self.trainedModel.data.approxParameters = copy(self.approxParameters)
if self.verbosity >= 5:
verbosityDepth("DEL", "Done setting up approximant.",
timestamp = self.timestamp)
def assembleReducedSystem(self, pMat : Np2D = None, pMatOld : Np2D = None)\
-> Tuple[List[Np2D], List[Np1D]]:
"""Build affine blocks of RB linear system through projections."""
if pMat is None:
self.setupApprox()
ARBs = self.trainedModel.data.ARBs
bRBs = self.trainedModel.data.bRBs
else:
if self.verbosity >= 10:
verbosityDepth("INIT", "Projecting affine terms of HF model.",
timestamp = self.timestamp)
ARBsOld = None if pMatOld is None else self.trainedModel.data.ARBs
bRBsOld = None if pMatOld is None else self.trainedModel.data.bRBs
ARBs, bRBs = projectAffineDecomposition(self.As, self.bs, pMat,
ARBsOld, bRBsOld, pMatOld)
if self.verbosity >= 10:
verbosityDepth("DEL", "Done projecting affine terms.",
timestamp = self.timestamp)
return ARBs, bRBs

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