Doesn't work in DifferentialEquations

[isentropic]

Following the example given here

https://github.com/JuliaDiffEq/DiffEqTutorials.jl/blob/master/ExtraODEFeatures/Solving%20Equations%20in%20With%20Julia-Defined%20Types.ipynb

With
Julia version

   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.0.3 (2018-12-18)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

Julia status

julia> Pkg.status()
    Status `~/.julia/environments/v1.0/Project.toml`
  [7e558dbc] ArbNumerics v0.2.6
  [55939f99] DecFP v0.4.7
  [225cb15b] DiffEqTutorials v0.0.0 #master (https://github.com/JuliaDiffEq/DiffEqTutorials.jl)
  [0c46a032] DifferentialEquations v5.3.1
  [ffa9a821] DocumentFormat v0.2.0
  [7073ff75] IJulia v1.15.2
  [2b0e0bc5] LanguageServer v0.5.0
  [2edaba10] Nemo v0.11.1
  [9b87118b] PackageCompiler v0.5.1
  [91a5bcdd] Plots v0.22.4
  [d330b81b] PyPlot v2.6.3
  [0d4725de] Readables v0.2.0
  [90137ffa] StaticArrays v0.10.2
  [b3cc710f] StaticLint v0.0.2
  [cf896787] SymbolServer v0.1.0
  [1986cc42] Unitful v0.14.0

[stevengj]

"Doesn't work" is not informative. What is the error? cc @ChrisRackauckas

(Decimal floating point seems to have few advantages for ODE integration, and a huge disadvantage in speed. But it would be good to make it work if only to make sure everything is sufficiently generic.)

[isentropic]

Sorry for the ambiguity. That is, if the example code from the notebook is run,

julia> prob_ode_decfplinear = ODEProblem(f,Dec128(1)/Dec128(2),(0.0,1.0))
ODEProblem with uType Dec128 and tType Float64. In-place: false
timespan: (0.0, 1.0)
u0: 0.5

julia> sol =solve(prob_ode_decfplinear,RK4(),dt=1//2^(6))
ERROR: MethodError: Dec128(::Dec128) is ambiguous. Candidates:
  (::Type{T})(x::T) where T<:Number in Core at boot.jl:725
  Dec128(x) in DecFP at /home/zhanibek/.julia/packages/DecFP/XA6lk/src/DecFP.jl:105
Possible fix, define
  Dec128(::Dec128)
Stacktrace:
 [1] oneunit(::Type{Dec128}) at ./number.jl:321
 [2] #__init#205(::Int64, ::Array{Float64,1}, ::Array{Float64,1}, ::Array{Float64,1}, ::Nothing, ::Bool, ::Nothing, ::Bool, ::Bool, ::Bool, ::Nothing, ::Bool, ::Bool, ::Rational{Int64}, ::Bool, ::Rational{Int64}, ::Nothing, ::Nothing, ::Int64, ::Rational{Int64}, ::Int64, ::Int64, ::Rational{Int64}, ::Bool, ::Int64, ::Nothing, ::Nothing, ::Int64, ::Float64, ::Float64, ::typeof(DiffEqBase.ODE_DEFAULT_NORM), ::typeof(LinearAlgebra.opnorm), ::typeof(DiffEqBase.ODE_DEFAULT_ISOUTOFDOMAIN), ::typeof(DiffEqBase.ODE_DEFAULT_UNSTABLE_CHECK), ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Bool, ::Int64, ::String, ::typeof(DiffEqBase.ODE_DEFAULT_PROG_MESSAGE), ::Nothing, ::Bool, ::Bool, ::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::typeof(DiffEqBase.__init), ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /home/zhanibek/.julia/packages/OrdinaryDiffEq/SXL9q/src/solve.jl:116
 [3] (::getfield(DiffEqBase, Symbol("#kw##__init")))(::NamedTuple{(:dt,),Tuple{Rational{Int64}}}, ::typeof(DiffEqBase.__init), ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at ./none:0
 [4] #__solve#204(::Base.Iterators.Pairs{Symbol,Rational{Int64},Tuple{Symbol},NamedTuple{(:dt,),Tuple{Rational{Int64}}}}, ::Function, ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at /home/zhanibek/.julia/packages/OrdinaryDiffEq/SXL9q/src/solve.jl:6
 [5] (::getfield(DiffEqBase, Symbol("#kw##__solve")))(::NamedTuple{(:dt,),Tuple{Rational{Int64}}}, ::typeof(DiffEqBase.__solve), ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4, ::Array{Any,1}, ::Array{Any,1}, ::Array{Any,1}, ::Type{Val{true}}) at ./none:0 (repeats 5 times)
 [6] #solve#442(::Base.Iterators.Pairs{Symbol,Rational{Int64},Tuple{Symbol},NamedTuple{(:dt,),Tuple{Rational{Int64}}}}, ::Function, ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4) at /home/zhanibek/.julia/packages/DiffEqBase/8usQ9/src/solve.jl:39
 [7] (::getfield(DiffEqBase, Symbol("#kw##solve")))(::NamedTuple{(:dt,),Tuple{Rational{Int64}}}, ::typeof(solve), ::ODEProblem{Dec128,Tuple{Float64,Float64},false,Nothing,ODEFunction{false,getfield(Main, Symbol("##3#4")),LinearAlgebra.UniformScaling{Bool},Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing,Nothing},Nothing,DiffEqBase.StandardODEProblem}, ::RK4) at ./none:0
 [8] top-level scope at none:0

Entry [4] in the notebook https://github.com/JuliaDiffEq/DiffEqTutorials.jl/blob/master/ExtraODEFeatures/Solving%20Equations%20in%20With%20Julia-Defined%20Types.ipynb

[stevengj]

Thanks, should be fixed now on the master branch.

(In the future, file issues for each specific error message that arises, not for the package where they happen to arise.)