Example on System of Fractional Differential Equations returned ‘ERROR: LoadError: UndefVarError: FODEProblem not defined’

[sky-y11]

My Julia version is 1.9.4
FractionalDiffeq version is 0.3.5

[ErikQQY]

Can you share an MWE? There should not be such errors since all the APIs are all standards now

[sky-y11]

julia> using FractionalDiffEq

julia> function chua!(du, x, p, t)
a, b, c, m0, m1 = p
du[1] = a*(x[2]-x[1]-(m1x[1]+0.5(m0-m1)(abs(x[1]+1)-abs(x[1]-1))))
du[2] = x[1]-x[2]+x[3]
du[3] = -bx[2]-c*x[3]
end
chua! (generic function with 1 method)

julia> α = [0.93, 0.99, 0.92];

julia> x0 = [0.2; -0.1; 0.1];

julia> tspan = (0, 100);

julia> p = [10.725, 10.593, 0.268, -1.1726, -0.7872]
5-element Vector{Float64}:
10.725
10.593
0.268
-1.1726
-0.7872

julia> prob = FODEProblem(chua!, α, x0, tspan, p)
ERROR: UndefVarError: FODEProblem not defined
Stacktrace:
[1] top-level scope
@ REPL[11]:1

julia> sol = solve(prob, BDF(), dt=0.01)
ERROR: UndefVarError: BDF not defined
Stacktrace:
[1] top-level scope
@ REPL[12]:1

(v1.9) pkg> pin FractionalDiffEq
Resolving package versions...
Updating F:\Program Files (x86)\julia-pkg\environments\v1.9\Project.toml
⌅ [c7492dd8] ~ FractionalDiffEq v0.3.1 ⇒ v0.3.1 ⚲
Updating F:\Program Files (x86)\julia-pkg\environments\v1.9\Manifest.toml
⌅ [c7492dd8] ~ FractionalDiffEq v0.3.1 ⇒ v0.3.1 ⚲
Info Packages marked with ⌅ have new versions available but compatibility constraints restrict them from upgrading. To see why use status --outdated -m

[sky-y11]

`julia> using FractionalDiffEq, Plots

[ Info: Precompiling Plots [91a5bcdd-55d7-5caf-9e0b-520d859cae80]
ERROR: LoadError: InitError: could not load library "C:\Users\ASUS.julia\artifacts\09e3c39a42811f9e36aa9071725a5e176004c32d\bin\libfreetype-6.dll"`

[ErikQQY]

The version of FractionalDiffEq.jl is way too old, could you upgrade the this package to the latest version and then try again?

[sky-y11]

`julia> using FractionalDiffEq

julia> function chua!(du, x, p, t)
a, b, c, m0, m1 = p
du[1] = a*(x[2]-x[1]-(m1x[1]+0.5(m0-m1)(abs(x[1]+1)-abs(x[1]-1))))
du[2] = x[1]-x[2]+x[3]
du[3] = -bx[2]-c*x[3]
end
chua! (generic function with 1 method)

julia> α = [0.93, 0.99, 0.92];

julia> x0 = [0.2; -0.1; 0.1];

julia> tspan = (0, 100);

julia> p = [10.725, 10.593, 0.268, -1.1726, -0.7872]
5-element Vector{Float64}:
10.725
10.593
0.268
-1.1726
-0.7872

julia> prob = FODEProblem(chua!, α, x0, tspan, p)
FODEProblem with uType Vector{Float64} and tType Int64. In-place: true
timespan: (0, 100)
u0: 3-element Vector{Float64}:
0.2
-0.1
0.1

julia> sol = solve(prob, BDF(), dt=0.01)
ERROR: ArgumentError: BDF method is only for commensurate order FODE
Stacktrace:
[1] __init(prob::FODEProblem{…}, alg::BDF; dt::Float64, reltol::Float64, abstol::Float64, maxiters::Int64, kwargs::@kwargs{})
@ FractionalDiffEq C:\Users\ASUS.julia\packages\FractionalDiffEq\M3BiW\src\fode\bdf.jl:50
[2] __init
@ C:\Users\ASUS.julia\packages\FractionalDiffEq\M3BiW\src\fode\bdf.jl:40 [inlined]
[3] #init_call#40
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:530 [inlined]
[4] init_call
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:503 [inlined]
[5] #init_up#43
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:564 [inlined]
[6] init_up
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:551 [inlined]
[7] #init#41
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:544 [inlined]
[8] init
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:534 [inlined]
[9] __solve(::FODEProblem{…}, ::BDF; kwargs::@kwargs{…})
@ FractionalDiffEq C:\Users\ASUS.julia\packages\FractionalDiffEq\M3BiW\src\FractionalDiffEq.jl:67
[10] __solve
@ C:\Users\ASUS.julia\packages\FractionalDiffEq\M3BiW\src\FractionalDiffEq.jl:66 [inlined]
[11] #solve_call#44
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:612 [inlined]
[12] solve_call
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:569 [inlined]
[13] #solve_up#53
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:1092 [inlined]
[14] solve_up
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:1078 [inlined]
[15] #solve#51
@ C:\Users\ASUS.julia\packages\DiffEqBase\frOsk\src\solve.jl:1015 [inlined]
[16] top-level scope
@ REPL[11]:1
Some type information was truncated. Use show(err) to see complete types.`

在我安装了0.5.0版本后无定义的问题得到了解决，但是BDF（）好像是只能求解阶数一样的微分方程

[ErikQQY]

ERROR: ArgumentError: BDF method is only for commensurate order FODE

是的，BDF算法是只支持同阶次FODE的求解的，你可以尝试一下PECE或者PITrap等算法