Type: GenericState

Methods: update!, reinit!

A generic State to describe the state of a problem at a point x.

Tracked data include:

• x : current iterate
• d [opt] : search direction
• res [opt] : residual
• current_time : time
• current_score : score

Constructors: GenericState(:: T, :: S; d :: T = _init_field(T), res :: T = _init_field(T), current_time :: Float64 = NaN) where {S, T <:AbstractVector}

GenericState(:: T; d :: T = _init_field(T), res :: T = _init_field(T), current_time :: Float64 = NaN, current_score :: Union{T,eltype(T)} = _init_field(eltype(T))) where T <:AbstractVector

Note:

• By default, unknown entries are set using _init_field.
• By default the type of current_score is eltype(x) and cannot be changed once the State is created. To have a vectorized current_score of length n, try something like GenericState(x, Array{eltype(x),1}(undef, n)).

Examples: GenericState(x) GenericState(x, Array{eltype(x),1}(undef, length(x))) GenericState(x, current_time = 1.0) GenericState(x, current_score = 1.0)

See also: Stopping, NLPAtX

Type: list of States

Constructor:

ListofStates(:: AbstractState)

ListofStates(n :: Int, :: Val{AbstractState})

ListofStates(n :: Int, list :: Array{AbstractState,1})

ListofStates(state :: S; n :: Int = -1, kwargs...)

Note:

• If n != -1, then it stores at most n AbstractState.
• ListofStates recursively handles sub-list of states as the attribute list is

an array of pair whose first component is a, AbstractState and the second component is a ListofStates (or VoidListofStates).

Examples: ListofStates(state) ListofStates(state, n = 2) ListofStates(-1, Val{NLPAtX}()) ListofStates(-1, [(state1, VoidListofStates), (state2, VoidListofStates)], 2)

Type: NLPAtX

Methods: update!, reinit!

NLPAtX contains the information concerning a nonlinear optimization model at the iterate x.

min_{x ∈ ℜⁿ} f(x) subject to lcon <= c(x) <= ucon, lvar <= x <= uvar.

Tracked data include:

• x : the current iterate

• fx [opt] : function evaluation at x

• gx [opt] : gradient evaluation at x

• Hx [opt] : hessian evaluation at x

• mu [opt] : Lagrange multiplier of the bounds constraints

• cx [opt] : evaluation of the constraint function at x

• Jx [opt] : jacobian matrix of the constraint function at x

• lambda : Lagrange multiplier of the constraints

• d [opt] : search direction

• res [opt] : residual

• current_time : time

• current_score : score

• evals [opt] : number of evaluations of the function

(import the type NLPModels.Counters)

Constructors: NLPAtX(:: T, :: T, :: S; fx :: eltype(T) = _init_field(eltype(T)), gx :: T = _init_field(T), Hx :: Matrix{eltype(T)} = _init_field(Matrix{eltype(T)}), mu :: T = _init_field(T), cx :: T = _init_field(T), Jx :: Matrix{eltype(T)} = _init_field(Matrix{eltype(T)}), d :: T = _init_field(T), res :: T = _init_field(T), current_time :: Float64 = NaN, evals :: Counters = Counters()) where {S, T <: AbstractVector}

NLPAtX(:: T; fx :: eltype(T) = _init_field(eltype(T)), gx :: T = _init_field(T), Hx :: Matrix{eltype(T)} = _init_field(Matrix{eltype(T)}), mu :: T = _init_field(T), current_time :: Float64 = NaN, current_score :: Union{T,eltype(T)} = _init_field(eltype(T)), evals :: Counters = Counters()) where {T <: AbstractVector}

NLPAtX(:: T, :: T; fx :: eltype(T) = _init_field(eltype(T)), gx :: T = _init_field(T), Hx :: Matrix{eltype(T)} = _init_field(Matrix{eltype(T)}), mu :: T = _init_field(T), cx :: T = _init_field(T), Jx :: Matrix{eltype(T)} = _init_field(Matrix{eltype(T)}), d :: T = _init_field(T), res :: T = _init_field(T), current_time :: Float64 = NaN, current_score :: Union{T,eltype(T)} = _init_field(eltype(T)), evals :: Counters = Counters()) where T <: AbstractVector

Note:

• By default, unknown entries are set using _init_field (except evals).
• By default the type of current_score is eltype(x) and cannot be changed once the State is created. To have a vectorized current_score of length n, try something like GenericState(x, Array{eltype(x),1}(undef, n)).
• All these information (except for x and lambda) are optionnal and need to be update when required. The update is done through the update! function.
• x and lambda are mandatory entries. If no constraints lambda = [].
• The constructor check the size of the entries.

See also: GenericState, update!, update_and_start!, update_and_stop!, reinit!

Type: OneDAtX

Methods: update!, reinit!, copy

A structure designed to track line search information from one iteration to another. Given f : ℜⁿ → ℜ, define h(θ) = f(x + θ*d) where x and d are vectors of same dimension and θ is a scalar, more specifically the step size.

Tracked data can include:

• x : the current step size
• fx [opt] : h(θ) at the current iteration
• gx [opt] : h'(θ)
• f₀ [opt] : h(0)
• g₀ [opt] : h'(0)
• d [opt] : search direction
• res [opt] : residual
• current_time : the time at which the line search algorithm started.
• current_score : the score at which the line search algorithm started.

Constructors: OneDAtX(:: T, :: S; fx :: T = _init_field(T), gx :: T = _init_field(T), f₀ :: T = _init_field(T), g₀ :: T = _init_field(T), current_time :: Float64 = NaN) where {S, T <: Number}

OneDAtX(:: T; fx :: T = _init_field(T), gx :: T = _init_field(T), f₀ :: T = _init_field(T), g₀ :: T = _init_field(T), current_time :: Float64 = NaN, current_score :: T = _init_field(T)) where T <: Number

Note:

• By default, unknown entries are set using _init_field.
• By default the type of current_score is eltype(x) and cannot be changed once the State is created. To have a vectorized current_score of length n, use OneDAtX(x, Array{eltype(x),1}(undef, n)).

update!: generic update function for the State

update!(:: AbstractState; convert = false, kwargs...)

The function compares the kwargs and the entries of the State. If the type of the kwargs is the same as the entry, then it is updated.

Set kargs convert to true to update even incompatible types.

Examples: update!(state1) update!(state1, current_time = 2.0) update!(state1, convert = true, current_time = 2.0)

See also: GenericState, reinit!, update_and_start!, update_and_stop!

update!: generic update function for the Stopping

update!(:: AbstractStopping; kwargs...)

Shortcut for update!(stp.current_state; kwargs...)

reinit!: function that set all the entries at _init_field except the mandatory x.

reinit!(:: AbstractState, :: T; kwargs...)

Note: If x is given as a kargs it will be prioritized over the second argument.

Examples: reinit!(state2, zeros(2)) reinit!(state2, zeros(2), current_time = 1.0)

There is a shorter version of reinit! reusing the x in the state

reinit!(:: AbstractState; kwargs...)

Examples: reinit!(state2) reinit!(state2, current_time = 1.0)

reinit!: function that set all the entries at void except the mandatory x

reinit!(:: NLPAtX, x :: AbstractVector, l :: AbstractVector; kwargs...)

reinit!(:: NLPAtX; kwargs...)

Note: if x, lambda or evals are given as keyword arguments they will be prioritized over the existing x, lambda and the default Counters.

reinit!: reinitialize the meta-data in the Stopping.

reinit!(:: AbstractStopping; rstate :: Bool = false, kwargs...)

Note:

• If rstate is set as true it reinitializes the current State

(with the kwargs).

• If rlist is set as true the list of states is also reinitialized, either

set as a VoidListofStates if rstate is true or a list containing only the current state otherwise.

For NLPStopping, rcounters set as true also reinitialize the counters.

add_to_list!: add a State to the list of maximal size n. If a n+1-th State is added, the first one in the list is removed. The given is State is compressed before being added in the list (via State.copy_compress_state).

add_to_list!(:: AbstractListofStates, :: AbstractState; kwargs...)

Note:

• kwargs are passed to the compress_state call.
• does nothing for VoidListofStates

see also: ListofStates, State.compress_state, State.copy_compress_state

length: return the number of States in the list.

length(:: ListofStates)

see also: print, addtolist!, ListofStates

print: output formatting. return a DataFrame.

print(:: ListofStates; verbose :: Bool = true, print_sym :: Union{Nothing,Array{Symbol,1}})

Note:

• set verbose to false to avoid printing.
• if print_sym is an Array of Symbol, only those symbols are printed. Note that

the returned DataFrame still contains all the columns.

• More information about DataFrame: http://juliadata.github.io/DataFrames.jl

see also: add_to_list!, length, ListofStates

Type: GenericStopping

Methods: start!, stop!, update_and_start!, update_and_stop!, fill_in!, reinit!, status

A generic Stopping to solve instances with respect to some optimality conditions. Optimality is decided by computing a score, which is then tested to zero.

Tracked data include:

• pb : A problem
• state : The information relative to the problem, see GenericState.
• (opt) meta : Metadata relative to a stopping criterion, see StoppingMeta.
• (opt) main_stp : Stopping of the main loop in case we consider a Stopping of a subproblem. If not a subproblem, then nothing.
• (opt) listofstates : ListofStates designed to store the history of States.
• (opt) stoppinguserstruct : Contains any structure designed by the user.

Constructor: GenericStopping(:: Any, :: AbstractState; meta :: AbstractStoppingMeta = StoppingMeta(), main_stp :: Union{AbstractStopping, Nothing} = nothing, stopping_user_struct :: Any = nothing, kwargs...)

Note: Metadata can be provided by the user or created with the Stopping constructor via kwargs. If a specific StoppingMeta is given and kwargs are provided, the kwargs have priority.

Examples: GenericStopping(pb, GenericState(ones(2)), rtol = 1e-1)

Besides optimality conditions, we consider classical emergency exit: - domain error (for instance: NaN in x) - unbounded problem (not implemented) - unbounded x (x is too large) - tired problem (time limit attained) - resources exhausted (not implemented) - stalled problem (not implemented) - iteration limit (maximum number of iteration (i.e. nb of stop) attained) - main_pb limit (tired or resources of main problem exhausted)

There is an additional default constructor which creates a Stopping with a default State.

GenericStopping(:: Any, :: Union{Number, AbstractVector}; kwargs...)

Note: Keywords arguments are forwarded to the classical constructor.

Examples: GenericStopping(pb, x0, rtol = 1e-1)

Type: NLPStopping

Methods: start!, stop!, update_and_start!, update_and_stop!, fill_in!, reinit!, status KKT, unconstrained_check, unconstrained2nd_check, optim_check_bounded

Specialization of GenericStopping. Stopping structure for non-linear programming problems using NLPModels.

Attributes:

• pb : an AbstractNLPModel
• state : The information relative to the problem, see GenericState
• (opt) meta : Metadata relative to stopping criterion, see StoppingMeta.
• (opt) main_stp : Stopping of the main loop in case we consider a Stopping of a subproblem. If not a subproblem, then nothing.
• (opt) listofstates : ListofStates designed to store the history of States.
• (opt) stoppinguserstruct : Contains any structure designed by the user.

NLPStopping(:: AbstractNLPModel, :: AbstractState; meta :: AbstractStoppingMeta = StoppingMeta(), max_cntrs :: Dict = init_max_counters(), main_stp :: Union{AbstractStopping, Nothing} = nothing, list :: Union{ListofStates, Nothing} = nothing, stopping_user_struct :: Any = nothing, kwargs...)

Note:

• designed for NLPAtX State. Constructor checks that the State has the

required entries.

There is an additional default constructor creating a Stopping where the State is by default and the optimality function is the function KKT()`.

NLPStopping(pb :: AbstractNLPModel; kwargs...)

Note: Kwargs are forwarded to the classical constructor.

Type: LAStopping

Methods: start!, stop!, update_and_start!, update_and_stop!, fillin!, reinit!, status linear\system_check, normal_equation_check

Specialization of GenericStopping. Stopping structure for linear algebra solving either

$Ax = b$

or

$min\_{x} \tfrac{1}{2}\|Ax - b\|^2$.

Attributes:

• pb : a problem using LLSModel (designed for linear least square problem, see https://github.com/JuliaSmoothOptimizers/NLPModels.jl/blob/master/src/lls_model.jl )
• state : The information relative to the problem, see GenericState
• (opt) meta : Metadata relative to stopping criterion, see StoppingMeta.
• (opt) main_stp : Stopping of the main loop in case we consider a Stopping of a subproblem. If not a subproblem, then nothing.
• (opt) listofstates : ListofStates designed to store the history of States.
• (opt) stoppinguserstruct : Contains any structure designed by the user.

LAStopping(:: LLSModel, :: AbstractState; meta :: AbstractStoppingMeta = StoppingMeta() main_stp :: Union{AbstractStopping, Nothing} = nothing, stopping_user_struct :: Any = nothing, kwargs...)

Note:

• Kwargs are forwarded to the classical constructor.
• Not specific State targeted
• State don't necessarily keep track of evals
• Evals are checked only for pb.A being a LinearOperator
• zero_start is true if 0 is the initial guess (not check automatically)
• LLSModel counter follow NLSCounters (see initmaxcounters_NLS in NLPStoppingmod.jl)
• By default, meta.max_cntrs is initialized with an NLSCounters

There is additional constructors:

LAStopping(:: Union{AbstractLinearOperator, AbstractMatrix}, :: AbstractVector, kwargs...)

LAStopping(:: Union{AbstractLinearOperator, AbstractMatrix}, :: AbstractVector, :: AbstractState, kwargs...)

See also GenericStopping, NLPStopping, LS_Stopping, linear_system_check, normal_equation_check

Type: LACounters

Type: StoppingMeta

Methods: no methods.

Attributes:

• atol: absolute tolerance.

• rtol: relative tolerance.

• optimality0: optimality score at the initial guess.

• tol_check: Function of atol, rtol and optimality0 testing a score to zero.

• tolcheckneg: Function of atol, rtol and optimality0 testing a score to zero.

• check_pos: pre-allocation for positive tolerance

• check_neg: pre-allocation for negative tolerance

• recomp_tol: true if tolerances are updated

• optimality_check: a stopping criterion via an admissibility function

• unbounded_threshold: threshold for unboundedness of the problem.

• unbounded_x: threshold for unboundedness of the iterate.

• max_f: maximum number of function (and derivatives) evaluations.

• max_cntrs: Dict contains the maximum number of evaluations

• max_eval: maximum number of function (and derivatives) evaluations.

• max_iter: threshold on the number of stop! call/number of iteration.

• max_time: time limit to let the algorithm run.

• nb_of_stop: keep track of the number of stop! call/iteration.

• start_time: keep track of the time at the beginning.

• fail_sub_pb: status.

• unbounded: status.

• unbounded_pb: status.

• tired: status.

• stalled: status.

• iteration_limit: status.

• resources: status.

• optimal: status.

• infeasible: status.

• main_pb: status.

• domainerror: status.

• suboptimal: status.

• stopbyuser: status.

• exception: status.

• metauserstruct: Any

• usercheckfunc!: Function (AbstractStopping, Bool) -> callback.

StoppingMeta(;atol :: Number = 1.0e-6, rtol :: Number = 1.0e-15, optimality0 :: Number = 1.0, tol_check :: Function = (atol,rtol,opt0) -> max(atol,rtol*opt0), tol_check_neg :: Function = (atol,rtol,opt0) -> -max(atol,rtol*opt0), unbounded_threshold :: Number = 1.0e50, unbounded_x :: Number = 1.0e50, max_f :: Int = typemax(Int), max_eval :: Int = 20000, max_iter :: Int = 5000, max_time :: Number = 300.0, start_time :: Float64 = NaN, meta_user_struct :: Any = nothing, kwargs...)

an alternative with constant tolerances:

StoppingMeta(tol_check :: T, tol_check_neg :: T;atol :: Number = 1.0e-6, rtol :: Number = 1.0e-15, optimality0 :: Number = 1.0, unbounded_threshold :: Number = 1.0e50, unbounded_x :: Number = 1.0e50, max_f :: Int = typemax(Int), max_eval :: Int = 20000, max_iter :: Int = 5000, max_time :: Number = 300.0, start_time :: Float64 = NaN, meta_user_struct :: Any = nothing, kwargs...)

Note:

• It is a mutable struct, therefore we can modify elements of a StoppingMeta.
• The nb_of_stop is incremented everytime stop! or update_and_stop! is called
• The optimality0 is modified once at the beginning of the algorithm (start!)
• The start_time is modified once at the beginning of the algorithm (start!) if not precised before.
• The different status: fail_sub_pb, unbounded, unbounded_pb, tired, stalled, iteration_limit, resources, optimal, main_pb, domainerror, suboptimal, infeasible
• fail_sub_pb, suboptimal, and infeasible are modified by the algorithm.
• optimality_check takes two inputs (AbstractNLPModel, NLPAtX)

and returns a Number or an AbstractVector to be compared to 0.

• optimality_check does not necessarily fill in the State.

Examples: StoppingMeta(), StoppingMeta(1., -1.)

Update the Stopping and return true if we must stop.

start!(:: AbstractStopping; no_opt_check :: Bool = false, kwargs...)

Purpose is to know if there is a need to even perform an optimization algorithm or if we are at an optimal solution from the beginning. Set no_opt_check to true avoid checking optimality and domain errors.

The function start! successively calls: _domain_check(stp, x), _optimality_check!(stp, x), _null_test(stp, x) and _user_check!(stp, x, true).

Note: - start! initializes stp.meta.start_time (if not done before), stp.current_state.current_time and stp.meta.optimality0 (if no_opt_check is false). - Keywords argument are passed to the _optimality_check! call. - Compatible with the StopRemoteControl.

update_and_start!: update values in the State and initialize the Stopping. Returns the optimality status of the problem as a boolean.

update_and_start!(:: AbstractStopping; kwargs...)

Note:

• Kwargs are forwarded to the update! call.
• no_opt_check skip optimality check in start! (false by default).

stop!: update the Stopping and return a boolean true if we must stop.

stop!(:: AbstractStopping; kwargs...)

It serves the same purpose as start! in an algorithm; telling us if we stop the algorithm (because we have reached optimality or we loop infinitely, etc).

The function stop! successively calls: _domain_check, _optimality_check, _null_test, _unbounded_check!, _tired_check!, _resources_check!, _stalled_check!, _iteration_check!, _main_pb_check!, add_to_list!

Note:

• kwargs are sent to the _optimality_check! call.
• If listofstates != VoidListofStates, call add_to_list!.

update_and_stop!: update the values in the State and return the optimality status of the problem as a boolean.

update_and_stop!(stp :: AbstractStopping; kwargs...)

Note: Kwargs are forwarded to the update! call.

fill_in!: fill in the unspecified values of the AbstractState.

fill_in!(:: AbstractStopping, x :: Union{Number, AbstractVector})

Note: NotImplemented for Abstract/Generic-Stopping.

fill_in!: (NLPStopping version) a function that fill in the required values in the NLPAtX.

fill_in!( :: NLPStopping, :: Union{AbstractVector, Nothing}; fx :: Union{AbstractVector, Nothing} = nothing, gx :: Union{AbstractVector, Nothing} = nothing, Hx :: Union{MatrixType, Nothing} = nothing, cx :: Union{AbstractVector, Nothing} = nothing, Jx :: Union{MatrixType, Nothing} = nothing, lambda :: Union{AbstractVector, Nothing} = nothing, mu :: Union{AbstractVector, Nothing} = nothing, matrix_info :: Bool = true, kwargs...)

status: returns the status of the algorithm:

status(:: AbstractStopping; list = false)

The different statuses are:

• Optimal: reached an optimal solution.
• SubProblemFailure
• SubOptimal: reached an acceptable solution.
• Unbounded: current iterate too large in norm.
• UnboundedPb: unbouned problem.
• Stalled: stalled algorithm.
• IterationLimit: too many iterations of the algorithm.
• TimeLimit: time limit.
• EvaluationLimit: too many ressources used, i.e. too many functions evaluations.
• ResourcesOfMainProblemExhausted: in the case of a substopping, EvaluationLimit or TimeLimit for the main stopping.
• Infeasible: default return value, if nothing is done the problem is considered feasible.
• StopByUser: stopped by the user.
• DomainError: there is a NaN somewhere.
• Exception: unhandled exception
• Unknwon: if stopped for reasons unknown by Stopping.

Note:

• Set keyword argument list to true, to get an Array with all the statuses.
• The different statuses correspond to boolean values in the meta.

init_max_counters: initialize the maximum number of evaluations on each of the functions present in the NLPModels.Counters, e.g.

init_max_counters(; allevals :: T = 20000, obj = allevals, grad = allevals, cons = allevals, jcon = allevals, jgrad = allevals, jac = allevals, jprod = allevals, jtprod = allevals, hess = allevals, hprod = allevals, jhprod = allevals, sum = 11 * allevals, kwargs...)

:neval_sum is by default limited to |Counters| * allevals.

init_max_counters_NLS: initialize the maximum number of evaluations on each of the functions present in the NLPModels.NLSCounters, e.g.

init_max_counters_NLS(; allevals = 20000, residual = allevals, jac_residual = allevals, jprod_residual = allevals, jtprod_residual = allevals, hess_residual = allevals, jhess_residual = allevals, hprod_residual = allevals, kwargs...)

init_max_counters_linear_operators: counters for LinearOperator

init_max_counters_linear_operators(; allevals :: T = 20000, nprod = allevals, ntprod = allevals, nctprod = allevals, sum = 11 * allevals)

KKT: verifies the KKT conditions

KKT( :: AbstractNLPModel, :: NLPAtX; pnorm :: Float64 = Inf, kwargs...)

Note: state.gx is mandatory + if bounds state.mu + if constraints state.cx, state.Jx, state.lambda.

See also unconstrained_check, unconstrained2nd_check, optim_check_bounded

unconstrained_check: return the infinite norm of the gradient of the objective function

unconstrained_check( :: AbstractNLPModel, :: NLPAtX; pnorm :: Float64 = Inf, kwargs...)

Require state.gx (filled if not provided)

See also unconstrained2nd_check, optim_check_bounded, KKT

unconstrained2nd_check: check the norm of the gradient and the smallest eigenvalue of the hessian.

unconstrained2nd_check( :: AbstractNLPModel, :: NLPAtX; pnorm :: Float64 = Inf, kwargs...)

Require are state.gx, state.Hx (filled if not provided).

See also unconstrained_check, optim_check_bounded, KKT

optim_check_bounded: gradient of the objective function projected

optim_check_bounded( :: AbstractNLPModel, :: NLPAtX; pnorm :: Float64 = Inf, kwargs...)

Require state.gx (filled if not provided).

See also unconstrained_check, unconstrained2nd_check, KKT

linear_system_check: return ||Ax-b||_p

linear_system_check(:: Union{LinearSystem, LLSModel}, :: AbstractState; pnorm :: Float64 = Inf, kwargs...)

Note:

• Returns the p-norm of state.res
• state.res is filled in if nothing.

normal_equation_check: return ||A'Ax-A'b||_p

normal_equation_check(:: Union{LinearSystem, LLSModel}, :: AbstractState; pnorm :: Float64 = Inf, kwargs...)

Note: pb must have A and b entries

armijo: check if a step size is admissible according to the Armijo criterion.

Armijo criterion: f(x + θd) - f(x) - τ₀ θ ∇f(x+θd)d < 0

armijo(h :: Any, h_at_t :: OneDAtX; τ₀ :: Float64 = 0.01, kwargs...)

Note: fx, f₀ and g₀ are required in the OneDAtX

See also wolfe, armijo_wolfe, shamanskii_stop, goldstein

wolfe: check if a step size is admissible according to the Wolfe criterion.

Strong Wolfe criterion: |∇f(x+θd)| < τ₁||∇f(x)||.

wolfe(h :: Any, h_at_t :: OneDAtX; τ₁ :: Float64 = 0.99, kwargs...)

Note: gx and g₀ are required in the OneDAtX

See also armijo, armijo_wolfe, shamanskii_stop, goldstein

armijo_wolfe: check if a step size is admissible according to the Armijo and Wolfe criteria.

armijo_wolfe(h :: Any, h_at_t :: OneDAtX; τ₀ :: Float64 = 0.01, τ₁ :: Float64 = 0.99, kwargs...)

Note: fx, f₀, gx and g₀ are required in the OneDAtX

See also armijo, wolfe, shamanskii_stop, goldstein

shamanskii_stop: check if a step size is admissible according to the "Shamanskii" criteria. This criteria was proposed in: Lampariello, F., & Sciandrone, M. (2001). Global convergence technique for the Newton method with periodic Hessian evaluation. Journal of optimization theory and applications, 111(2), 341-358.

shamanskii_stop(h :: Any, h_at_t :: OneDAtX; γ :: Float64 = 1.0e-09, kwargs...)

Note:

• h.d accessible (specific LineModel)
• fx, f₀ are required in the OneDAtX

See also armijo, wolfe, armijo_wolfe, goldstein

goldstein: check if a step size is admissible according to the Goldstein criteria.

goldstein(h :: Any, h_at_t :: OneDAtX; τ₀ :: Float64 = 0.0001, τ₁ :: Float64 = 0.9999, kwargs...)

Note: fx, f₀ and g₀ are required in the OneDAtX

See also armijo, wolfe, armijo_wolfe, shamanskii_stop