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Solving ODE system fails with MethodError depending on interval endpoint

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#749 1 commento 0 reazioni 0 assegnatari Vedi su GitHub

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Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
35/100
Tipo di issue
Bug
Chiarezza
Abbastanza chiara
Stato di attività
Ferma
Stack tecnologico
julia
Ambito
backend

Direzione di ricerca

Inizia eseguendo la riproduzione allegata approxfun_issue_cf_min.jl, confrontando works() con fail_methoderror() e con lo stacktrace setdomain segnalato. Leggi i metodi setdomain di ApproxFunBase nominati nel trace e gli entry point autodifferentiation/newton di ApproxFun. Il lavoro è completato quando il fallimento dipendente dall’endpoint viene gestito in modo deterministico o limitato come descritto nell’issue.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

The attached code shows two cases of attempting to solve an ODE problem using ApproxFun. Changing the interval endpoint, without any other code changes, results in a shift from successful solutions to a MethodError. The code is a self-contained reproduction case that has been stripped down, with hardcoded initial values. It results in the error whose stacktrace is given below on an AMD64 system running Linux; the ApproxFun version used was 0.12.5.

Invoke works() to see a successful solve, and fail_methoderror() to see the error/stacktrace corresponding to:

ERROR: MethodError: no method matching 
setdomain(::PiecewiseSpace{Tuple{Chebyshev{ChebyshevInterval{Float64},Float64},JacobiWeight{Chebyshev{Interval{:closed,:closed,Float64},Float64},Interval{:closed,:closed,Float64},Float64,Int64},JacobiWeight{Chebyshev{Interval{:closed,:closed,Float64},Float64},Interval{:closed,:closed,Float64},Float64,Int64}},DomainSets.UnionDomain{Float64,Tuple{ChebyshevInterval{Float64},Interval{:closed,:closed,Float64},Interval{:closed,:closed,Float64}}},Float64}, ::Interval{:closed,:closed,Float64})
Closest candidates are:
  setdomain(::ApproxFunBase.SumSpace, ::Domain) at /home/user/.julia/packages/ApproxFunBase/Gra7W/src/Spaces/SumSpace.jl:105
  setdomain(::PiecewiseSpace, ::DomainSets.UnionDomain) at /home/user/.julia/packages/ApproxFunBase/Gra7W/src/Spaces/SumSpace.jl:108
  setdomain(::ApproxFunBase.ArraySpace, ::Domain) at /home/user/.julia/packages/ApproxFunBase/Gra7W/src/Spaces/ArraySpace.jl:67
  ...
Stacktrace:
 [1] setdomain(::Fun{PiecewiseSpace{Tuple{Chebyshev{ChebyshevInterval{Float64},Float64},JacobiWeight{Chebyshev{Interval{:closed,:closed,Float64},Float64},Interval{:closed,:closed,Float64},Float64,Int64},JacobiWeight{Chebyshev{Interval{:closed,:closed,Float64},Float64},Interval{:closed,:closed,Float64},Float64,Int64}},DomainSets.UnionDomain{Float64,Tuple{ChebyshevInterval{Float64},Interval{:closed,:closed,Float64},Interval{:closed,:closed,Float64}}},Float64},Float64,Array{Float64,1}}, ::Interval{:closed,:closed,Float64}) at /home/user/.julia/packages/ApproxFunBase/Gra7W/src/Fun.jl:184
 [2] /(::Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}}, ::Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}}) at /home/user/.julia/packages/ApproxFunBase/Gra7W/src/specialfunctions.jl:98
 [3] /(::ApproxFun.DualFun{Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}},PlusOperator{Float64,Tuple{Int64,Int64}}}, ::ApproxFun.DualFun{Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}},ApproxFunBase.ConstantTimesOperator{PlusOperator{Float64,Tuple{Int64,Int64}},Float64}}) at /home/user/.julia/packages/ApproxFun/GOMNa/src/Extras/autodifferentiation.jl:55
 [4] (::var"#N#1"{Float64,Float64,Float64,Float64})(::ApproxFun.DualFun{Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}},ConstantOperator{Float64,Chebyshev{Interval{:closed,:closed,Float64},Float64}}}, ::Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}}) at /home/user/research_code/approxfun_issue_cf_min.jl:14
 [5] newton(::Function, ::Array{Fun{Chebyshev{Interval{:closed,:closed,Float64},Float64},Float64,Array{Float64,1}},1}; maxiterations::Int64, tolerance::Float64) at /home/user/.julia/packages/ApproxFun/GOMNa/src/Extras/autodifferentiation.jl:137
 [6] approxfun_final_ode_step(::Float64) at /home/user/research_code/approxfun_issue_cf_min.jl:21
 [7] solve_test at /home/user/research_code/approxfun_issue_cf_min.jl:28 [inlined]
 [8] fail_methoderror() at /home/user/research_code/approxfun_issue_cf_min.jl:36
 [9] top-level scope at REPL[3]:1

Notes:

  1. I used a fairly coarse tolerance in the Newton solver, and still get this error.
  2. It takes a number of minutes for the failing case to arrive at the error. A lot of work of some kind is occurring.
  3. A singularity occurs in the ODE solution within the interval, in both the works() and fail_methoderror() cases; in fact, this is the motivation for using ApproxFun.jl rather than DifferentialEquations.jl. I only care about the solution before it reaches the singularity, but do not know a priori where the singularity is.
  4. If this happens to be a pathological set of inputs, it would be very helpful to get some kind of deterministic error/exception, or to be able to set limits on how hard ApproxFun tries to build suitable approximations (whether memory/size of matrices, tolerances, etc.). Since in an arbitrary problem solve, the location of the singularity is not known a priori , robustness would be needed in the solution attempt.

Code (I wasn't able to upload without appending a .txt extension):
approxfun_issue_cf_min.jl.txt

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