pymor.algorithms package¶
Submodules¶
adaptivegreedy module¶

class
pymor.algorithms.adaptivegreedy.
AdaptiveSampleSet
(parameter_space)[source]¶ Bases:
pymor.core.interfaces.BasicInterface
An adaptive parameter sample set.
Used by
adaptive_greedy
.Methods
AdaptiveSampleSet
map_vertex_to_mu
,refine
,visualize
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
AdaptiveSampleSet
Element
BasicInterface
logger
,logging_disabled
,name
,uid

pymor.algorithms.adaptivegreedy.
_estimate
(mu, rd=None, d=None, reductor=None, error_norm=None)[source]¶ Called by
adaptive_greedy
.

pymor.algorithms.adaptivegreedy.
adaptive_greedy
(d, reductor, parameter_space=None, use_estimator=True, error_norm=None, target_error=None, max_extensions=None, validation_mus=0, rho=1.1, gamma=0.2, theta=0.0, extension_params=None, visualize=False, visualize_vertex_size=80, pool=<pymor.parallel.dummy.DummyPool object>)[source]¶ Greedy basis generation algorithm with adaptively refined training set.
This method extends pyMOR’s default
greedy
greedy basis generation algorithm by adaptive refinement of the parameter training set according to [HDO11] to prevent overfitting of the reduced basis to the training set. This is achieved by estimating the reduction error on an additional validation set of parameters. If the ratio between the estimated errors on the validation set and the validation set is larger thanrho
, the training set is refined using standard grid refinement techniques.[HDO11] Haasdonk, B.; Dihlmann, M. & Ohlberger, M., A training set and multiple bases generation approach for parameterized model reduction based on adaptive grids in parameter space, Math. Comput. Model. Dyn. Syst., 2011, 17, 423442 Parameters
 d
 See
greedy
.  reductor
 See
greedy
.  parameter_space
 The
ParameterSpace
for which to compute the reduced model. IfNone
, the parameter space ofd
is used.  use_estimator
 See
greedy
.  error_norm
 See
greedy
.  target_error
 See
greedy
.  max_extensions
 See
greedy
.  validation_mus
 One of the following:
 a list of
Parameters
to use as validation set,  a positive number indicating the number of random parameters to use as validation set,
 a nonpositive number, indicating the negative number of random parameters to use as validation set in addition to the centers of the elements of the adaptive training set.
 a list of
 rho
 Maximum allowed ratio between maximum estimated error on validation set vs. maximum estimated error on training set. If the ratio is larger, the training set is refined.
 gamma
 Weight of the age penalty term in the training set refinement indicators.
 theta
 Ratio of training set elements to select for refinement. (One element is always refined.)
 extension_params
 See
greedy
.  visualize
 If
True
, visualize the refinement indicators. (Only available for 2 and 3 dimensional parameter spaces.)  visualize_vertex_size
 Size of the vertices in the visualization.
 pool
 See
greedy
.
Returns
Dict with the following fields
rd: The reduced Discretization
obtained for the computed basis.extensions: Number of greedy iterations. max_errs: Sequence of maximum errors during the greedy run. max_err_mus: The parameters corresponding to max_errs
.max_val_errs: Sequence of maximum errors on the validation set. max_val_err_mus: The parameters corresponding to max_val_errs
.refinements: Number of refinements made in each extension step. training_set_sizes: The final size of the training set in each extension step. time: Duration of the algorithm. reduction_data: Reduction data returned by the last reductor call.
basic module¶
Module containing some basic but generic linear algebra algorithms.

pymor.algorithms.basic.
almost_equal
(U, V, product=None, norm=None, rtol=1e14, atol=1e14)[source]¶ Compare U and V for almost equality.
The vectors of
U
andV
are compared in pairs for almost equality. Two vectorsu
andv
are considered almost equal iffu  v <= atol + v * rtol.The norm to be used can be specified via the
norm
orproduct
parameter.If the length of
U
resp.V
is 1, the single specified vector is compared to all vectors of the other array. Otherwise, the lengths of both indexed arrays have to agree.Parameters
 U, V
VectorArrays
to be compared. product
 If specified, use this inner product
Operator
to compute the norm.product
andnorm
are mutually exclusive.  norm
 If specified, must be a callable, which is used to compute the norm
or, alternatively, one of the string ‘l1’, ‘l2’, ‘sup’, in which case the
respective
VectorArray
norm methods are used.product
andnorm
are mutually exclusive. If neither is specified,norm='l2'
is assumed.  rtol
 The relative tolerance.
 atol
 The absolute tolerance.
Defaults
rtol, atol (see
pymor.core.defaults
)

pymor.algorithms.basic.
project_array
(U, basis, product=None, orthonormal=True)[source]¶ Orthogonal projection of
VectorArray
onto subspace.Parameters
 U
 The
VectorArray
to project.  basis
VectorArray
of basis vectors for the subspace onto which to project. product
 Inner product
Operator
w.r.t. which to project.  orthonormal
 If
True
, the vectors inbasis
are assumed to be orthonormal w.r.t.product
.
Returns
The projected
VectorArray
.
ei module¶
This module contains algorithms for the empirical interpolation of Operators
.
The main work for generating the necessary interpolation data is handled by
the ei_greedy
method. The objects returned by this method can be used
to instantiate an EmpiricalInterpolatedOperator
.
As a convenience, the interpolate_operators
method allows to perform
the empirical interpolation of the Operators
of a given discretization with
a single function call.

pymor.algorithms.ei.
deim
(U, modes=None, atol=None, rtol=None, product=None, pod_options={})[source]¶ Generate data for empirical interpolation using DEIM algorithm.
Given a
VectorArray
U
, this method generates a collateral basis and interpolation DOFs for empirical interpolation of the vectors contained inU
. The returned objects can be used to instantiate anEmpiricalInterpolatedOperator
(withtriangular=False
).The collateral basis is determined by the first
pod
modes ofU
.Parameters
 U
 A
VectorArray
of vectors to interpolate.  modes
 Dimension of the collateral basis i.e. number of POD modes of the vectors in
U
.  atol
 Absolute POD tolerance.
 rtol
 Relative POD tolerance.
 product
 Inner product
Operator
used for the POD.  pod_options
 Dictionary of additional options to pass to the
pod
algorithm.
Returns
 interpolation_dofs
NumPy array
of the DOFs at which the vectors are interpolated. collateral_basis
VectorArray
containing the generated collateral basis. data
Dict containing the following fields:
svals: POD singular values.

pymor.algorithms.ei.
ei_greedy
(U, error_norm=None, atol=None, rtol=None, max_interpolation_dofs=None, copy=True, pool=<pymor.parallel.dummy.DummyPool object>)[source]¶ Generate data for empirical interpolation using EIGreedy algorithm.
Given a
VectorArray
U
, this method generates a collateral basis and interpolation DOFs for empirical interpolation of the vectors contained inU
. The returned objects can be used to instantiate anEmpiricalInterpolatedOperator
(withtriangular=True
).The interpolation data is generated by a greedy search algorithm, where in each loop iteration the worst approximated vector in
U
is added to the collateral basis.Parameters
 U
 A
VectorArray
of vectors to interpolate.  error_norm
 Norm w.r.t. which to calculate the interpolation error. If
None
, the Euclidean norm is used.  atol
 Stop the greedy search if the largest approximation error is below this threshold.
 rtol
 Stop the greedy search if the largest relative approximation error is below this threshold.
 max_interpolation_dofs
 Stop the greedy search if the number of interpolation DOF (= dimension of the collateral basis) reaches this value.
 copy
 If
False
,U
will be modified during executing of the algorithm.  pool
 If not
None
, theWorkerPool
to use for parallelization.
Returns
 interpolation_dofs
NumPy array
of the DOFs at which the vectors are evaluated. collateral_basis
VectorArray
containing the generated collateral basis. data
Dict containing the following fields:
errors: Sequence of maximum approximation errors during greedy search. triangularity_errors: Sequence of maximum absolute values of interoplation matrix coefficients in the upper triangle (should be near zero).

pymor.algorithms.ei.
interpolate_operators
(d, operator_names, parameter_sample, error_norm=None, product=None, atol=None, rtol=None, max_interpolation_dofs=None, pod_options={}, alg='ei_greedy', pool=<pymor.parallel.dummy.DummyPool object>)[source]¶ Empirical operator interpolation using the EIGreedy/DEIM algorithm.
This is a convenience method to facilitate the use of
ei_greedy
ordeim
. Given aDiscretization
, names ofOperators
, and a sample ofParameters
, first the operators are evaluated on the solution snapshots of the discretization for the provided parameters. These evaluations are then used as input forei_greedy
/deim
. Finally the resulting interpolation data is used to createEmpiricalInterpolatedOperators
and a new discretization with the interpolated operators is returned.Note that this implementation creates one common collateral basis for all specified operators, which might not be what you want.
Parameters
 d
 The
Discretization
whoseOperators
will be interpolated.  operator_names
 List of keys in the
operators
dict of the discretization. The correspondingOperators
will be interpolated.  parameter_sample
 A list of
Parameters
for which solution snapshots are calculated.  error_norm
 See
ei_greedy
. Has no effect ifalg == 'deim'
.  product
 Inner product for POD computation in
deim
. Has no effect ifalg == 'ei_greedy'
.  atol
 See
ei_greedy
.  rtol
 See
ei_greedy
.  max_interpolation_dofs
 See
ei_greedy
.  pod_options
 Further options for
pod
algorithm. Has no effect ifalg == 'ei_greedy'
.  alg
 Either
ei_greedy
ordeim
.  pool
 If not
None
, theWorkerPool
to use for parallelization.
Returns
 ei_d
Discretization
withOperators
given byoperator_names
replaced byEmpiricalInterpolatedOperators
. data
Dict containing the following fields:
dofs: NumPy array
of the DOFs at which theOperators
have to be evaluated.basis: VectorArray
containing the generated collateral basis.errors: Sequence of maximum approximation errors during greedy search. triangularity_errors: Sequence of maximum absolute values of interoplation matrix coefficients in the upper triangle (should be near zero).
error module¶

pymor.algorithms.error.
reduction_error_analysis
(rd, d, reductor, test_mus=10, basis_sizes=0, random_seed=None, estimator=True, condition=False, error_norms=(), error_norm_names=None, estimator_norm_index=0, custom=(), plot=False, plot_custom_logarithmic=True, pool=<pymor.parallel.dummy.DummyPool object>)[source]¶ Analyze the model reduction error.
The maximum model reduction error is estimated by solving the reduced
Discretization
for given randomParameters
.Parameters
 rd
 The reduced
Discretization
.  d
 The highdimensional
Discretization
.  reductor
 The reductor which has created
rd
.  test_mus
 Either a list of
Parameters
to compute the errors for, or the number of parameters which are sampled randomly fromparameter_space
(if given) orrd.parameter_space
.  basis_sizes
 Either a list of reduced basis dimensions to consider, or
the number of dimensions (which are then selected equidistantly,
always including the maximum reduced space dimension).
The dimensions are input for the
dim
Parameter ofreductor.reduce()
.  random_seed
 If
test_mus
is a number, use this value as random seed for drawing theParameters
.  estimator
 If
True
evaluate the error estimator ofrd
on the testParameters
.  condition
 If
True
, compute the condition of the reduced system matrix for the given testParameters
(can only be specified ifrd
is an instance ofStationaryDiscretization
andrd.operator
is linear).  error_norms
 List of norms in which to compute the model reduction error.
 error_norm_names
 Names of the norms given by
error_norms
. IfNone
, thename
attributes of the given norms are used.  estimator_norm_index
 When
estimator
isTrue
anderror_norms
are specified, this is the index of the norm inerror_norms
w.r.t. which to compute the effectivity of the estimator.  custom
List of custom functions which are evaluated for each test
Parameter
and basis size. The functions must have the signaturedef custom_value(rd, d, reductor, mu, dim): pass
 plot
 If
True
, generate a plot of the computed quantities w.r.t. the basis size.  plot_custom_logarithmic
 If
True
, use a logarithmic yaxis to plot the computed custom values.  pool
 If not
None
, theWorkerPool
to use for parallelization.
Returns
Dict with the following fields
mus: The test Parameters
which have been considered.basis_sizes: The reduced basis dimensions which have been considered. norms: NumPy array
of the norms of the highdimensional solutions w.r.t. all given testParameters
, reduced basis dimensions and norms inerror_norms
. (Only present whenerror_norms
has been specified.)max_norms: Maxima of norms
over the given testParameters
.max_norm_mus: Parameters
corresponding tomax_norms
.errors: NumPy array
of the norms of the model reduction errors w.r.t. all given testParameters
, reduced basis dimensions and norms inerror_norms
. (Only present whenerror_norms
has been specified.)max_errors: Maxima of errors
over the given testParameters
.max_error_mus: Parameters
corresponding tomax_errors
.rel_errors: errors
divided bynorms
. (Only present whenerror_norms
has been specified.)max_rel_errors: Maxima of rel_errors
over the given testParameters
.max_rel_error_mus: Parameters
corresponding tomax_rel_errors
.error_norm_names: Names of the given error_norms
. (Only present whenerror_norms
has been specified.)estimates: NumPy array
of the model reduction error estimates w.r.t. all given testParameters
and reduced basis dimensions. (Only present whenestimator
isTrue
.)max_estimate: Maxima of estimates
over the given testParameters
.max_estimate_mus: Parameters
corresponding tomax_estimates
.effectivities: errors
divided byestimates
. (Only present whenestimator
isTrue
anderror_norms
has been specified.)min_effectivities: Minima of effectivities
over the given testParameters
.min_effectivity_mus: Parameters
corresponding tomin_effectivities
.max_effectivities: Maxima of effectivities
over the given testParameters
.max_effectivity_mus: Parameters
corresponding tomax_effectivities
.errors: NumPy array
of the reduced system matrix conditions w.r.t. all given testParameters
and reduced basis dimensions. (Only present whenconditions
isTrue
.)max_conditions: Maxima of conditions
over the given testParameters
.max_condition_mus: Parameters
corresponding tomax_conditions
.custom_values: NumPy array
of custom function evaluations w.r.t. all given testParameters
, reduced basis dimensions and functions incustom
. (Only present whencustom
has been specified.)max_custom_values: Maxima of custom_values
over the given testParameters
.max_custom_values_mus: Parameters
corresponding tomax_custom_values
.time: Time (in seconds) needed for the error analysis. summary: String containing a summary of all computed quantities for the largest (last) considered basis size. figure: The figure containing the generated plots. (Only present when plot
isTrue
.)
genericsolvers module¶
This module contains some iterative linear solvers which only use the Operator
interface

pymor.algorithms.genericsolvers.
apply_inverse
(op, rhs, options=None, least_squares=False, check_finite=True, default_solver='generic_lgmres', default_least_squares_solver='generic_least_squares_lsmr')[source]¶ Solve linear equation system.
Applies the inverse of
op
to the vectors inrhs
using a generic iterative solver.Parameters
 op
 The linear, nonparametric
Operator
to invert.  rhs
VectorArray
of righthand sides for the equation system. options
 The
solver_options
to use (seesolver_options
).  check_finite
 Test if solution only containes finite values.
 default_solver
 Default solver to use (generic_lgmres, generic_least_squares_lsmr, generic_least_squares_lsqr).
 default_least_squares_solver
 Default solver to use for least squares problems (generic_least_squares_lsmr, generic_least_squares_lsqr).
Returns
VectorArray
of the solution vectors.Defaults
check_finite, default_solver, default_least_squares_solver (see
pymor.core.defaults
)

pymor.algorithms.genericsolvers.
lgmres
(A, b, x0=None, tol=1e05, maxiter=1000, M=None, callback=None, inner_m=30, outer_k=3, outer_v=None, store_outer_Av=True)[source]¶

pymor.algorithms.genericsolvers.
lsmr
(A, b, damp=0.0, atol=1e06, btol=1e06, conlim=100000000.0, maxiter=None, show=False)[source]¶

pymor.algorithms.genericsolvers.
lsqr
(A, b, damp=0.0, atol=1e08, btol=1e08, conlim=100000000.0, iter_lim=None, show=False)[source]¶

pymor.algorithms.genericsolvers.
solver_options
(lgmres_tol=1e05, lgmres_maxiter=1000, lgmres_inner_m=39, lgmres_outer_k=3, least_squares_lsmr_damp=0.0, least_squares_lsmr_atol=1e06, least_squares_lsmr_btol=1e06, least_squares_lsmr_conlim=100000000.0, least_squares_lsmr_maxiter=None, least_squares_lsmr_show=False, least_squares_lsqr_damp=0.0, least_squares_lsqr_atol=1e06, least_squares_lsqr_btol=1e06, least_squares_lsqr_conlim=100000000.0, least_squares_lsqr_iter_lim=None, least_squares_lsqr_show=False)[source]¶ Returns available solvers with default
solver_options
.Parameters
 lgmres_tol
 See
scipy.sparse.linalg.lgmres
.  lgmres_maxiter
 See
scipy.sparse.linalg.lgmres
.  lgmres_inner_m
 See
scipy.sparse.linalg.lgmres
.  lgmres_outer_k
 See
scipy.sparse.linalg.lgmres
.  least_squares_lsmr_damp
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsmr_atol
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsmr_btol
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsmr_conlim
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsmr_maxiter
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsmr_show
 See
scipy.sparse.linalg.lsmr
.  least_squares_lsqr_damp
 See
scipy.sparse.linalg.lsqr
.  least_squares_lsqr_atol
 See
scipy.sparse.linalg.lsqr
.  least_squares_lsqr_btol
 See
scipy.sparse.linalg.lsqr
.  least_squares_lsqr_conlim
 See
scipy.sparse.linalg.lsqr
.  least_squares_lsqr_iter_lim
 See
scipy.sparse.linalg.lsqr
.  least_squares_lsqr_show
 See
scipy.sparse.linalg.lsqr
.
Returns
A dict of available solvers with default
solver_options
.Defaults
lgmres_tol, lgmres_maxiter, lgmres_inner_m, lgmres_outer_k, least_squares_lsmr_damp, least_squares_lsmr_atol, least_squares_lsmr_btol, least_squares_lsmr_conlim, least_squares_lsmr_maxiter, least_squares_lsmr_show, least_squares_lsqr_atol, least_squares_lsqr_btol, least_squares_lsqr_conlim, least_squares_lsqr_iter_lim, least_squares_lsqr_show (see
pymor.core.defaults
)
gram_schmidt module¶

pymor.algorithms.gram_schmidt.
gram_schmidt
(A, product=None, atol=1e13, rtol=1e13, offset=0, find_duplicates=True, reiterate=True, reiteration_threshold=0.1, check=True, check_tol=0.001, copy=True)[source]¶ Orthonormalize a
VectorArray
using the stabilized GramSchmidt algorithm.Parameters
 A
 The
VectorArray
which is to be orthonormalized.  product
 The inner product
Operator
w.r.t. which to orthonormalize. IfNone
, the Euclidean product is used.  atol
 Vectors of norm smaller than
atol
are removed from the array.  rtol
 Relative tolerance used to detect linear dependent vectors (which are then removed from the array).
 offset
 Assume that the first
offset
vectors are already orthonormal and start the algorithm at theoffset + 1
th vector.  reiterate
 If
True
, orthonormalize again if the norm of the orthogonalized vector is much smaller than the norm of the original vector.  reiteration_threshold
 If
reiterate
isTrue
, reorthonormalize if the ratio between the norms of the orthogonalized vector and the original vector is smaller than this value.  check
 If
True
, check if the resultingVectorArray
is really orthonormal.  check_tol
 Tolerance for the check.
 copy
 If
True
, create a copy ofA
instead of modifyingA
inplace.  find_duplicates
 unused
Returns
The orthonormalized
VectorArray
.Defaults
atol, rtol, reiterate, reiteration_threshold, check, check_tol (see
pymor.core.defaults
)

pymor.algorithms.gram_schmidt.
gram_schmidt_biorth
(V, W, product=None, reiterate=True, reiteration_threshold=0.1, check=True, check_tol=0.001, copy=True)[source]¶ Biorthonormalize a pair of
VectorArrays
using the biorthonormal GramSchmidt process.See Algorithm 1 in [BKS11].
[BKS11] P. Benner, M. Köhler, J. Saak, SparseDense Sylvester Equations in Model Order Reduction, Max Planck Institute Magdeburg Preprint, available from http://www.mpimagdeburg.mpg.de/preprints/, 2011. Parameters
 V, W
 The
VectorArrays
which are to be biorthonormalized.  product
 The inner product
Operator
w.r.t. which to biorthonormalize. IfNone
, the Euclidean product is used.  reiterate
 If
True
, orthonormalize again if the norm of the orthogonalized vector is much smaller than the norm of the original vector.  reiteration_threshold
 If
reiterate
isTrue
, reorthonormalize if the ratio between the norms of the orthogonalized vector and the original vector is smaller than this value.  check
 If
True
, check if the resultingVectorArray
is really orthonormal.  check_tol
 Tolerance for the check.
 copy
 If
True
, create a copy ofV
andW
instead of modifyingV
andW
inplace.
Returns
The biorthonormalized
VectorArrays
.
greedy module¶

pymor.algorithms.greedy.
greedy
(d, reductor, samples, use_estimator=True, error_norm=None, atol=None, rtol=None, max_extensions=None, extension_params=None, pool=None)[source]¶ Greedy basis generation algorithm.
This algorithm generates a reduced basis by iteratively adding the worst approximated solution snapshot for a given training set to the reduced basis. The approximation error is computed either by directly comparing the reduced solution to the detailed solution or by using an error estimator (
use_estimator == True
). The reduction and basis extension steps are performed by calling the methods provided by thereductor
andextension_algorithm
arguments.Parameters
 d
 The
Discretization
to reduce.  reductor
 Reductor for reducing the given
Discretization
. This has to be a an object with areduce
method, such thatreductor.reduce()
yields the reduced discretization, and anexted_basis
method, such thatreductor.extend_basis(U, copy_U=False, **extension_params)
extends the current reduced basis by the vectors contained inU
. For an example seeCoerciveRBReductor
.  samples
 The set of
Parameter
samples on which to perform the greedy search.  use_estimator
 If
True
, userd.estimate()
to estimate the errors on the sample set. Otherwised.solve()
is called to compute the exact model reduction error.  error_norm
 If
use_estimator == False
, use this function to calculate the norm of the error. IfNone
, the Euclidean norm is used.  atol
 If not
None
, stop the algorithm if the maximum (estimated) error on the sample set drops below this value.  rtol
 If not
None
, stop the algorithm if the maximum (estimated) relative error on the sample set drops below this value.  max_extensions
 If not
None
, stop the algorithm aftermax_extensions
extension steps.  extension_params
dict
of parameters passed to thereductor.extend_basis
method. pool
 If not
None
, theWorkerPool
to use for parallelization.
Returns
Dict with the following fields
rd: The reduced Discretization
obtained for the computed basis.max_errs: Sequence of maximum errors during the greedy run. max_err_mus: The parameters corresponding to max_errs
.extensions: Number of performed basis extensions. time: Total runtime of the algorithm. reduction_data: The reduction_data
returned by the lastreductor
call.
image module¶

class
pymor.algorithms.image.
CollectOperatorRangeRules
(source, image, extends)[source]¶ Bases:
pymor.algorithms.rules.RuleTable
RuleTable
for theestimate_image
algorithm.Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
CollectOperatorRangeRules
action_apply_operator
,action_Concatenation
,action_EmpiricalInterpolatedOperator
,action_recurse
,rules
BasicInterface
logger
,logging_disabled
,name
,uid

class
pymor.algorithms.image.
CollectVectorRangeRules
(image)[source]¶ Bases:
pymor.algorithms.rules.RuleTable
RuleTable
for theestimate_image
algorithm.Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
CollectVectorRangeRules
action_as_range_array
,action_Concatenation
,action_recurse
,action_VectorArray
,rules
BasicInterface
logger
,logging_disabled
,name
,uid

pymor.algorithms.image.
estimate_image
(operators=(), vectors=(), domain=None, extends=False, orthonormalize=True, product=None, riesz_representatives=False)[source]¶ Estimate the image of given
Operators
for all mu.Let
operators
be a list ofOperators
with common source and range, and letvectors
be a list ofVectorArrays
or vectorlikeOperators
in the range of these operators. Given aVectorArray
domain
of vectors in the source of the operators, this algorithms determines aVectorArray
image
of range vectors such that the linear span ofimage
contains:op.apply(U, mu=mu)
for all operatorsop
inoperators
, for all possibleParameters
mu
and for allVectorArrays
U
contained in the linear span ofdomain
,U
for allVectorArrays
invectors
,v.as_range_array(mu)
for allOperators
invectors
and all possibleParameters
mu
.
The algorithm will try to choose
image
as small as possible. However, no optimality is guaranteed. The image estimation algorithm is specified byCollectOperatorRangeRules
andCollectVectorRangeRules
.Parameters
 operators
 See above.
 vectors
 See above.
 domain
 See above. If
None
, an emptydomain
VectorArray
is assumed.  extends
 For some operators, e.g.
EmpiricalInterpolatedOperator
, as well as for all elements ofvectors
,image
is estimated independently from the choice ofdomain
. Ifextends
isTrue
, such operators are ignored. (This is useful in case these vectors have already been obtained by earlier calls to this function.)  orthonormalize
 Compute an orthonormal basis for the linear span of
image
using thegram_schmidt
algorithm.  product
 Inner product
Operator
w.r.t. which to orthonormalize.  riesz_representatives
 If
True
, compute Riesz representatives of the vectors inimage
before orthonormalizing (useful for dual norm computation when the range of theoperators
is a dual space).
Returns
The
VectorArray
image
.Raises
 ImageCollectionError
 Is raised when for a given
Operator
no image estimate is possible.

pymor.algorithms.image.
estimate_image_hierarchical
(operators=(), vectors=(), domain=None, extends=None, orthonormalize=True, product=None, riesz_representatives=False)[source]¶ Estimate the image of given
Operators
for all mu.This is an extended version of
estimate_image
, which callsestimate_image
individually for each vector ofdomain
.As a result, the vectors in the returned
image
VectorArray
will be ordered by thedomain
vector they correspond to (starting with vectors which correspond to the elements ofvectors
and toOperators
for which the image is estimated independently fromdomain
).This function also returns an
image_dims
list, such that the firstimage_dims[i+1]
vectors ofimage
correspond to the firsti
vectors ofdomain
(the firstimage_dims[0]
vectors correspond tovectors
and toOperators
with fixed image estimate).Parameters
 operators
 See
estimate_image
.  vectors
 See
estimate_image
.  domain
 See
estimate_image
.  extends
 When additional vectors have been appended to the
domain
VectorArray
afterestimate_image_hierarchical
has been called, andestimate_image_hierarchical
shall be called again for the extendeddomain
array,extends
can be set to(image, image_dims)
, whereimage
,image_dims
are the return values of the lastestimate_image_hierarchical
call. The olddomain
vectors will then be skipped during computation andimage
,image_dims
will be modified inplace.  orthonormalize
 See
estimate_image
.  product
 See
estimate_image
.  riesz_representatives
 See
estimate_image
.
Returns
 image
 See above.
 image_dims
 See above.
Raises
 ImageCollectionError
 Is raised when for a given
Operator
no image estimate is possible.
newton module¶

pymor.algorithms.newton.
newton
(operator, rhs, initial_guess=None, mu=None, error_norm=None, least_squares=False, miniter=0, maxiter=100, rtol=1.0, atol=1.0, stagnation_window=3, stagnation_threshold=0.9, return_stages=False, return_residuals=False)[source]¶ Basic Newton algorithm.
This method solves the nonlinear equation
A(U, mu) = V
for
U
using the Newton method.Parameters
 operator
 The
Operator
A
.A
must implement thejacobian
interface method.  rhs
VectorArray
of length 1 containing the vectorV
. initial_guess
 If not
None
, aVectorArray
of length 1 containing an initial guess for the solutionU
.  mu
 The
Parameter
for which to solve the equation.  error_norm
 The norm with which the norm of the residual is computed. If
None
, the Euclidean norm is used.  least_squares
 If
True
, use a least squares linear solver (e.g. for residual minimization).  miniter
 Minimum amount of iterations to perform.
 maxiter
 Fail if the iteration count reaches this value without converging.
 rtol
 Finish when the residual norm has been reduced by this factor relative to the norm of the initial residual.
 atol
 Finish when the residual norm is below this threshold.
 stagnation_window
 Finish when the residual norm has not been reduced by a factor of
stagnation_threshold
during the laststagnation_window
iterations.  stagnation_threshold
 See
stagnation_window
.  return_stages
 If
True
, return aVectorArray
of the intermediate approximations ofU
after each iteration.  return_residuals
 If
True
, return aVectorArray
of all residual vectors which have been computed during the Newton iterations.
Returns
 U
VectorArray
of length 1 containing the computed solution data
Dict containing the following fields:
error_sequence: NumPy array
containing the residual norms after each iteration.stages: See return_stages
.residuals: See return_residuals
.
Raises
 NewtonError
 Raised if the Netwon algorithm failed to converge.
Defaults
miniter, maxiter, rtol, atol, stagnation_window, stagnation_threshold (see
pymor.core.defaults
)
pod module¶

pymor.algorithms.pod.
pod
(A, modes=None, product=None, rtol=4e08, atol=0.0, l2_err=0.0, symmetrize=False, orthonormalize=True, check=True, check_tol=1e10)[source]¶ Proper orthogonal decomposition of
A
.Viewing the
VectorArray
A
as aA.dim
xlen(A)
matrix, the return value of this method is theVectorArray
of leftsingular vectors of the singular value decomposition ofA
, where the inner product on R^(dim(A)
) is given byproduct
and the inner product on R^(len(A)
) is the Euclidean inner product.Parameters
 A
 The
VectorArray
for which the POD is to be computed.  modes
 If not
None
, only the firstmodes
POD modes (singular vectors) are returned.  product
 Inner product
Operator
w.r.t. which the POD is computed.  rtol
 Singular values smaller than this value multiplied by the largest singular value are ignored.
 atol
 Singular values smaller than this value are ignored.
 l2_err
Do not return more modes than needed to bound the l2approximation error by this value. I.e. the number of returned modes is at most
argmin_N { sum_{n=N+1}^{infty} s_n^2 <= l2_err^2 }
where
s_n
denotes the nth singular value. symmetrize
 If
True
, symmetrize the Gramian again before proceeding.  orthonormalize
 If
True
, orthonormalize the computed POD modes again using thegram_schmidt
algorithm.  check
 If
True
, check the computed POD modes for orthonormality.  check_tol
 Tolerance for the orthonormality check.
Returns
 POD
VectorArray
of POD modes. SVALS
 Sequence of singular values.
Defaults
rtol, atol, l2_err, symmetrize, orthonormalize, check, check_tol (see
pymor.core.defaults
)
preassemble module¶

class
pymor.algorithms.preassemble.
PreAssembleRules
[source]¶ Bases:
pymor.algorithms.rules.RuleTable
Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
PreAssembleRules
action_AdjointOperator
,action_assemble
,action_identity
,action_recurse
,action_recurse_and_assemble
,rules
BasicInterface
logger
,logging_disabled
,name
,uid
projection module¶

class
pymor.algorithms.projection.
ProjectRules
(range_basis, source_basis, product)[source]¶ Bases:
pymor.algorithms.rules.RuleTable
RuleTable
for theproject
algorithm.Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ProjectRules
action_AdjointOperator
,action_AffineOperator
,action_apply_basis
,action_Concatenation
,action_ConstantOperator
,action_EmpiricalInterpolatedOperator
,action_generic_projection
,action_recurse
,action_ZeroOperator
,rules
BasicInterface
logger
,logging_disabled
,name
,uid

class
pymor.algorithms.projection.
ProjectToSubbasisRules
(dim_range, dim_source)[source]¶ Bases:
pymor.algorithms.rules.RuleTable
RuleTable
for theproject_to_subbasis
algorithm.Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ProjectToSubbasisRules
action_ConstantOperator
,action_NumpyMatrixOperator
,action_ProjectedEmpiciralInterpolatedOperator
,action_ProjectedOperator
,action_recurse
,rules
BasicInterface
logger
,logging_disabled
,name
,uid

pymor.algorithms.projection.
project
(op, range_basis, source_basis, product=None)[source]¶ PetrovGalerkin projection of a given
Operator
.Given an inner product
( ⋅, ⋅)
, source vectorsb_1, ..., b_N
and range vectorsc_1, ..., c_M
, the projectionop_proj
ofop
is defined by[ op_proj(e_j) ]_i = ( c_i, op(b_j) )
for all i,j, where
e_j
denotes the jth canonical basis vector of R^N.In particular, if the
c_i
are orthonormal w.r.t. the given product, thenop_proj
is the coordinate representation w.r.t. theb_i/c_i
bases of the restriction ofop
tospan(b_i)
concatenated with the orthogonal projection ontospan(c_i)
.From another point of view, if
op
is viewed as a bilinear form (seeapply2
) and( ⋅, ⋅ )
is the Euclidean inner product, thenop_proj
represents the matrix of the bilinear form restricted tospan(b_i) / span(c_i)
(w.r.t. theb_i/c_i
bases).How the projection is realized will depend on the given
Operator
. While a projectedNumpyMatrixOperator
will again be aNumpyMatrixOperator
, only a genericProjectedOperator
can be returned in general. The exact algorithm is specified inProjectRules
.Parameters
 range_basis
 The vectors
c_1, ..., c_M
as aVectorArray
. IfNone
, no projection in the range space is performed.  source_basis
 The vectors
b_1, ..., b_N
as aVectorArray
orNone
. IfNone
, no restriction of the source space is performed.  product
 An
Operator
representing the inner product. IfNone
, the Euclidean inner product is chosen.
Returns
The projected
Operator
op_proj
.

pymor.algorithms.projection.
project_to_subbasis
(op, dim_range=None, dim_source=None)[source]¶ Project given already projected
Operator
to a subbasis.The purpose of this method is to further project an operator that has been obtained through
project
to subbases of the original projection bases, i.e.project_to_subbasis(project(op, r_basis, s_basis, prod), dim_range, dim_source)
should be the same as
project(op, r_basis[:dim_range], s_basis[:dim_source], prod)
For a
NumpyMatrixOperator
this amounts to extracting the upperleft (dim_range, dim_source) corner of its matrix.The subbasis projection algorithm is specified in
ProjectToSubbasisRules
.Parameters
 dim_range
 Dimension of the range subbasis.
 dim_source
 Dimension of the source subbasis.
Returns
The projected
Operator
.
rules module¶

class
pymor.algorithms.rules.
RuleTable
(use_caching=False)[source]¶ Bases:
pymor.core.interfaces.BasicInterface
Define algorithm by a table of match conditions and corresponding actions.
RuleTable
manages a table ofrules
, stored in therules
attributes, which can beapplied
to given objects.A new table is created by subclassing
RuleTable
and defining new methods which are decorated withmatch_class
,match_generic
or anotherrule
subclass. The order of the method definitions determines the order in which the definedrules
are applied.Parameters
 use_caching
 If
True
, cache results ofapply
.
Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
RuleTable
rules
BasicInterface
logger
,logging_disabled
,name
,uid

apply
(obj)[source]¶ Sequentially apply rules to given object.
This method iterates over all rules of the given
RuleTable
. For eachrule
, it is checked if itmatches
the given object. IfFalse
, the nextrule
in the table is considered. IfTrue
the correspondingaction
is executed withobj
as parameter. If execution ofaction
raisesRuleNotMatchingError
, the rule is considered as not matching, and execution continues with evaluation of the next rule. Otherwise, execution is stopped and the return value ofrule.action
is returned to the caller.If no
rule
matches, aNoMatchingRuleError
is raised.Parameters
 obj
 The object to apply the
RuleTable
to.
Returns
Return value of the action of the first matching
rule
in the table.Raises
 NoMatchingRuleError
 No
rule
could be applied to the given object.

apply_children
(obj, children=None)[source]¶ Apply rules to all children of the given object.
This method calls
apply
to each child of the given object. The children of the object are either provided by thechildren
parameter or authomatically infered by theget_children
method.Parameters
 obj
 The object to apply the
RuleTable
to.  children
None
or a list of attribute names defining the children to consider.
Returns
Result of : meth:
apply
for all given children.

classmethod
get_children
(obj)[source]¶ Determine children of given object.
This method returns a list of the names of all attributes
a
, for which one of the folling is true:

replace_children
(obj, children=None)[source]¶ Replace children of object according to rule table.
Same as
apply_children
, but additionally callsobj.with_
to replace the children ofobj
with the result of the correspondingapply
call.

class
pymor.algorithms.rules.
RuleTableMeta
(name, bases, namespace)[source]¶ Bases:
pymor.core.interfaces.UberMeta
Meta class for
RuleTable
.Methods
ABCMeta
register
,__instancecheck__
,__subclasscheck__
type
mro
,__dir__
,__prepare__
,__sizeof__
,__subclasses__

static
__new__
(cls, name, parents, dct)[source]¶ I copy docstrings from base class methods to deriving classes.
Copying of docstrings is disabled when the
PYMOR_WITH_SPHINX
environment variable is set to1
.

__str__
()¶ Return repr(self).

static

class
pymor.algorithms.rules.
match_class
(*classes)[source]¶ Bases:
pymor.algorithms.rules.rule
rule
that matches when obj is instance of one of the given classes.Methods
match_class
matches
Attributes
match_class
condition_type
rule
action
,action_description
,condition_description
,source

class
pymor.algorithms.rules.
match_generic
(condition, condition_description=None)[source]¶ Bases:
pymor.algorithms.rules.rule
rule
with matching condition given by an arbitrary function.Parameters
 condition
 Function of one argument which checks if given object matches condition.
 condition_description
 Optional string describing the condition implemented by
condition
.
Methods
match_generic
matches
Attributes
match_generic
condition_type
rule
action
,action_description
,condition_description
,source

class
pymor.algorithms.rules.
rule
[source]¶ Bases:
object
Decorator to make a method a rule in a given
RuleTable
.The decorated function will become the
action
to perform in case the rulematches
. Matching conditions are specified by subclassing and overriding thematches
method.
action
¶ Method to call in case the rule matches.

timestepping module¶
This module provides generic timestepping algorithms for the solution of instationary problems.
The algorithms are generic in the sense that each algorithms operates exclusively
on Operators
and VectorArrays
. In particular, the algorithms
can also be used to turn an arbitrary stationary Discretization
provided
by an external library into an instationary Discretization
.
Currently, implementations of explicit_euler
and implicit_euler
timestepping are provided. The TimeStepperInterface
defines a
common interface that has to be fulfilled by the timesteppers used
by InstationaryDiscretization
. The classes ExplicitEulerTimeStepper
and ImplicitEulerTimeStepper
encapsulate explicit_euler
and
implicit_euler
to provide this interface.

class
pymor.algorithms.timestepping.
ExplicitEulerTimeStepper
(nt)[source]¶ Bases:
pymor.algorithms.timestepping.TimeStepperInterface
Explicit Euler timestepper.
Solves equations of the form
M * d_t u + A(u, mu, t) = F(mu, t).
Parameters
 nt
 The number of timesteps the timestepper will perform.
Methods
ExplicitEulerTimeStepper
solve
ImmutableInterface
generate_sid
,with_
,__setattr__
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ImmutableInterface
add_with_arguments
,sid
,sid_ignore
,with_arguments
BasicInterface
logger
,logging_disabled
,name
,uid

solve
(initial_time, end_time, initial_data, operator, rhs=None, mass=None, mu=None, num_values=None)[source]¶ Apply timestepper to the equation
M * d_t u + A(u, mu, t) = F(mu, t).
Parameters
 initial_time
 The time at which to begin timestepping.
 end_time
 The time until which to perform timestepping.
 initial_data
 The solution vector at
initial_time
.  operator
 The
Operator
A.  rhs
 The righthand side F (either
VectorArray
of length 1 orOperator
withsource.dim == 1
). IfNone
, zero righthand side is assumed.  mass
 The
Operator
M. IfNone
, the identity operator is assumed.  mu
Parameter
for whichoperator
andrhs
are evaluated. The current time is added tomu
with key_t
. num_values
 The number of returned vectors of the solution trajectory. If
None
, each intermediate vector that is calculated is returned.
Returns
VectorArray
containing the solution trajectory.

class
pymor.algorithms.timestepping.
ImplicitEulerTimeStepper
(nt, solver_options='operator')[source]¶ Bases:
pymor.algorithms.timestepping.TimeStepperInterface
Implict Euler timestepper.
Solves equations of the form
M * d_t u + A(u, mu, t) = F(mu, t).
Parameters
 nt
 The number of timesteps the timestepper will perform.
 solver_options
 The
solver_options
used to invertM + dt*A
. The special values'mass'
and'operator'
are recognized, in which case the solver_options of M (resp. A) are used.
Methods
ImplicitEulerTimeStepper
solve
ImmutableInterface
generate_sid
,with_
,__setattr__
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ImmutableInterface
add_with_arguments
,sid
,sid_ignore
,with_arguments
BasicInterface
logger
,logging_disabled
,name
,uid

solve
(initial_time, end_time, initial_data, operator, rhs=None, mass=None, mu=None, num_values=None)[source]¶ Apply timestepper to the equation
M * d_t u + A(u, mu, t) = F(mu, t).
Parameters
 initial_time
 The time at which to begin timestepping.
 end_time
 The time until which to perform timestepping.
 initial_data
 The solution vector at
initial_time
.  operator
 The
Operator
A.  rhs
 The righthand side F (either
VectorArray
of length 1 orOperator
withsource.dim == 1
). IfNone
, zero righthand side is assumed.  mass
 The
Operator
M. IfNone
, the identity operator is assumed.  mu
Parameter
for whichoperator
andrhs
are evaluated. The current time is added tomu
with key_t
. num_values
 The number of returned vectors of the solution trajectory. If
None
, each intermediate vector that is calculated is returned.
Returns
VectorArray
containing the solution trajectory.

class
pymor.algorithms.timestepping.
TimeStepperInterface
[source]¶ Bases:
pymor.core.interfaces.ImmutableInterface
Interface for timestepping algorithms.
Algorithms implementing this interface solve timedependent problems of the form
M * d_t u + A(u, mu, t) = F(mu, t).
Timesteppers used by
InstationaryDiscretization
have to fulfill this interface.Methods
TimeStepperInterface
solve
ImmutableInterface
generate_sid
,with_
,__setattr__
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ImmutableInterface
add_with_arguments
,sid
,sid_ignore
,with_arguments
BasicInterface
logger
,logging_disabled
,name
,uid

solve
(initial_time, end_time, initial_data, operator, rhs=None, mass=None, mu=None, num_values=None)[source]¶ Apply timestepper to the equation
M * d_t u + A(u, mu, t) = F(mu, t).
Parameters
 initial_time
 The time at which to begin timestepping.
 end_time
 The time until which to perform timestepping.
 initial_data
 The solution vector at
initial_time
.  operator
 The
Operator
A.  rhs
 The righthand side F (either
VectorArray
of length 1 orOperator
withsource.dim == 1
). IfNone
, zero righthand side is assumed.  mass
 The
Operator
M. IfNone
, the identity operator is assumed.  mu
Parameter
for whichoperator
andrhs
are evaluated. The current time is added tomu
with key_t
. num_values
 The number of returned vectors of the solution trajectory. If
None
, each intermediate vector that is calculated is returned.
Returns
VectorArray
containing the solution trajectory.


pymor.algorithms.timestepping.
explicit_euler
(A, F, U0, t0, t1, nt, mu=None, num_values=None)[source]¶
to_matrix module¶

class
pymor.algorithms.to_matrix.
ToMatrixRules
(format, mu)[source]¶ Bases:
pymor.algorithms.rules.RuleTable
Methods
RuleTable
append_rule
,apply
,apply_children
,get_children
,insert_rule
,replace_children
BasicInterface
disable_logging
,enable_logging
,has_interface_name
,implementor_names
,implementors
Attributes
ToMatrixRules
action_AdjointOperator
,action_BlockOperator
,action_ComponentProjection
,action_Concatenation
,action_IdentityOperator
,action_LincombOperator
,action_NumpyMatrixOperator
,action_VectorArrayOperator
,action_ZeroOperator
,rules
BasicInterface
logger
,logging_disabled
,name
,uid

pymor.algorithms.to_matrix.
to_matrix
(op, format=None, mu=None)[source]¶ Transform construction of Operators to matrix
Parameters
 op
 Operator.
 format
 Format of the resulting matrix:
NumPy array
if ‘dense’, otherwise the appropriateSciPy spmatrix
. IfNone
, a choice between dense and sparse format is automatically made.  mu
Parameter
.
Returns
 res
 Equivalent matrix.