Moritz Schauer
You find me via e-mail (see my university contact information on http://www.math.chalmers.se/~smoritz/index.html) or on JuliaLang's Community Channels, e.g. Zulip or Slack (see, https://julialang.org/community/).
A statistical toolbox for diffusion processes and stochastic differential equations. Named after the Brownian Bridge.
License: Other
Moritz Schauer
You find me via e-mail (see my university contact information on http://www.math.chalmers.se/~smoritz/index.html) or on JuliaLang's Community Channels, e.g. Zulip or Slack (see, https://julialang.org/community/).
I plan to bring some oder into the zoo of integrators by introducing the following interface. Currently I am thinking of
For ODEs
solve!(method::ODESolver, X::SamplePath, x0, F::Function)
solve(method::ODESolver, x0, F::Function)
where for example method=BS3()
and for SDEs
solve!(method, X::SamplePath, x0, W, P)
solve!(method, X::SamplePath, x0, W, b, σ)
solve(method, x0, W, P)
solve(method, x0, W, b, σ)
bridge!(method, X::SamplePath, W, P)
bridge(method, W, P)
where for example method=Euler()
which should cover all cases needed in Bridge.
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Release notes:
Fix build and add #40 "fix reference to internal Zip2
for julia 1.1"
The tag name "v0.4.0-pre" is not of the appropriate SemVer form (vX.Y.Z).
cc: @mschauer
I am getting rid of the bi(i, x, P)
variants of the generic drift function b(t, x, P)
which take an index i
instead of a time t
. In future SDE solver will call
b((i,t), x, P)
with fallback b((i,t), x, P) = b(t, x, P)
and models which need the corresponding index and not only the time point t
to compute the drift should use dispatch to overwrite that fallback.
Real OU bridge was implemented in 7397f01
For the vector valued OU bridge some matrix algebra is missing, but the one-dimensional formulas give a good idea how the answer should look like.
JuliaMath/SpecialFunctions.jl#236 should replace the version in src/expint.jl
(once a new version of SpecialFunctions is tagged).
For exponential integrals with n>1, expint(n, 0.0) returns NaN, instead of 1/(n-1). Compare the behavior to scipy.special.expn, which returns the appropriate value.
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Hi, Thanks for all your work in making Bridge.jl available.
I'm new to Julia, and feeling my way in terms of leading/best-of-breed packages and idioms.
It seems to me that Bridge.jl is the best of breed diffusion simulating package - closely followed by the DiffEqNoiseProcess.jl, to my mind the BridgeDiffEq,jl supports that conclusion.
I am planning a package that likely would take as input an array such as that generated by Bridge.jl.
In that context I hoped you might share your thoughts on the usefulness of adopting JuliaDiffEq/LabelledArrays.jl.
I am getting the following error when trying to precompile Bridge (Julia v1.1 on Mac)
[ Info: Precompiling Bridge [2d3116d5-4b8f-5680-861c-71f149790274]
ERROR: LoadError: LoadError: UndefVarError: Zip2 not defined
Stacktrace:
[1] getproperty(::Module, ::Symbol) at ./sysimg.jl:13
[2] top-level scope at none:0
[3] include at ./boot.jl:326 [inlined]
[4] include_relative(::Module, ::String) at ./loading.jl:1038
[5] include at ./sysimg.jl:29 [inlined]
[6] include(::String) at /Users/antonio/.julia/packages/Bridge/s3VsI/src/Bridge.jl:1
[7] top-level scope at none:0
[8] include at ./boot.jl:326 [inlined]
[9] include_relative(::Module, ::String) at ./loading.jl:1038
[10] include(::Module, ::String) at ./sysimg.jl:29
[11] top-level scope at none:2
[12] eval at ./boot.jl:328 [inlined]
[13] eval(::Expr) at ./client.jl:404
[14] top-level scope at ./none:3
in expression starting at /Users/antonio/.julia/packages/Bridge/s3VsI/src/types.jl:127
in expression starting at /Users/antonio/.julia/packages/Bridge/s3VsI/src/Bridge.jl:101
ERROR: Failed to precompile Bridge [2d3116d5-4b8f-5680-861c-71f149790274] to /Users/antonio/.julia/compiled/v1.1/Bridge/cfWTr.ji.
Stacktrace:
[1] error(::String) at ./error.jl:33
[2] compilecache(::Base.PkgId, ::String) at ./loading.jl:1197
[3] _require(::Base.PkgId) at ./loading.jl:960
[4] require(::Base.PkgId) at ./loading.jl:858
[5] require(::Module, ::Symbol) at ./loading.jl:853```
This issue is held open for general feedback, feature requests and to coordinate contributions to the package; or just to say "hello".
Trying to run the examples on Julia 1.2, I encouter linspace deprecated and replaced by range and some problem with SArray here:
S = 9.0:0.05:11.0
Ρ = 26.0:0.05:30.0
Β = 2.0:0.02:4.0
θref = s0, Ρ[end÷2], Β[end÷2]
@show θref;
θref = (10.0, 27.95, 2.98)
llsurface = [loglikelihood((s0, ρ, β), θref, X) for ρ in Ρ, β in Β];
gives:
The size of type SArray{Tuple{S},T,1,S} where T where S
is not known.
If you were trying to construct (or convert
to) a StaticArray
you
may need to add the size explicitly as a type parameter so its size is
inferrable to the Julia compiler (or performance would be terrible). For
example, you might try
m = zeros(3,3)
SMatrix(m) # this error
SMatrix{3,3}(m) # correct - size is inferrable
Stacktrace:
[1] error(::String) at .\error.jl:33
[2] missing_size_error(::Type{SArray{Tuple{S},T,1,S} where T where S}) at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\traits.jl:72
[3] Size(::Type{SArray{Tuple{S},T,1,S} where T where S}) at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\traits.jl:88
[4] length(::Type{SArray{Tuple{S},T,1,S} where T where S}) at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\abstractarray.jl:2
[5] convert at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\convert.jl:22 [inlined]
[6] Type at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\convert.jl:7 [inlined]
[7] Diagonal{T,SArray{Tuple{N},T,1,N}} where T where N(::Diagonal{Float64,SArray{Tuple{3},Float64,1,3}}) at C:\Users\Denis.julia\packages\StaticArrays\DBECI\src\SDiagonal.jl:7
[8] σ at C:\Users\Denis.julia\packages\Bridge\vPofv\src\Models.jl:57 [inlined]
[9] a(::Float64, ::SArray{Tuple{3},Float64,1,3}, ::Lorenz) at C:\Users\Denis.julia\packages\Bridge\vPofv\src\types.jl:32
[10] Γ(::Float64, ::SArray{Tuple{3},Float64,1,3}, ::Lorenz) at C:\Users\Denis.julia\packages\Bridge\vPofv\src\types.jl:33
[11] girsanov(::SamplePath{SArray{Tuple{3},Float64,1,3}}, ::Lorenz, ::Lorenz) at C:\Users\Denis.julia\packages\Bridge\vPofv\src\diffusion.jl:119
[12] loglikelihood(::Tuple{Float64,Float64,Float64}, ::Tuple{Float64,Float64,Float64}, ::SamplePath{SArray{Tuple{3},Float64,1,3}}) at .\In[36]:4
[13] (::getfield(Main, Symbol("##17#18")))(::Tuple{Float64,Float64}) at .\none:0
[14] iterate at .\generator.jl:47 [inlined]
[15] collect(::Base.Generator{Base.Iterators.ProductIterator{Tuple{StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}},StepRangeLen{Float64,Base.TwicePrecision{Float64},Base.TwicePrecision{Float64}}}},getfield(Main, Symbol("##17#18"))}) at .\array.jl:606
[16] top-level scope at In[38]:1
I am looking to run experiments to calculate first exits across a boundary using Levy-driven SDE. Does this package have a quick and dirty way to simulate
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I am working on a more flexible implementation of SamplePath
. I hope you appreciate renaming tt
and yy
fields t
and x
.
You can follow design here:
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