add file

Author: oscarddssmith

src/ODE_nlsolve.jl

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+"""
+    $(TYPEDEF)
+
+A collection of all the data required for custom ODE Nonlinear problem solving
+"""
+struct ODE_NLProb{NLProb, UNLProb, NLProbMap, NLProbPmap}
+    """
+    The `AbstractNonlinearProblem` to define custom nonlinear problems to be used for
+    implicit time discretizations. This allows to use extra structure of the ODE function (e.g.
+    multi-level structure). The nonlinear function must match that form of the function implicit
+    ODE integration algorithms need do solve the a nonlinear problems,
+    specifically of the form `z = outer_tmp + dt⋅f(γ⋅z+inner_tmp,p,t)`.
+    Here `z` is the stage solution vector, `p` is the parameter of the ODE problem, `t` is
+    the time, `dt` the respective time increment`, `γ` is some scaling factor and the temporary
+    variables are some compatible vectors set by the specific solver.
+    Note that this field will not be used for integrators such as fully-implicit Runge-Kutta methods
+    that need to solve different nonlinear systems.
+    The inner nonlinear function of the nonlinear problem is in general of the form `g(z,p') = 0`
+    where `p'` is a NamedTuple with all information about the specific nonlinear problem at hand to solve
+    for a specific time discretization. Specifically, it is `(;dt, γ, inner_tmp, outer_tmp, t, p)`, such that
+    `g(z,p') = dt⋅f(γ⋅z+inner_tmp,p,t) + outer_tmp - z = 0`.
+    """
+    nlprob::NLProb
+    """
+    A function which takes `(nlprob, value_provider)` and updates
+    the parameters of the former with their values in the latter.
+    If absent (`nothing`) this will not be called, and the parameters
+    in `nlprob` will be used without modification. `value_provider`
+    refers to a value provider as defined by SymbolicIndexingInterface.jl.
+    Usually this will refer to a problem or integrator.
+    """
+    update_nlprob!::UNLProb
+    """
+    A function which takes the solution of `nlprob` and returns
+    the state vector of the original problem.
+    """
+    nlprobmap::NLProbMap
+    """
+    A function which takes the solution of `nlprob` and returns
+    the parameter object of the original problem. If absent (`nothing`),
+    this will not be called and the parameters of the problem being
+    solved will be returned as-is.
+    """
+    nlprobpmap::NLProbPmap
+
+    function ODE_NLProb(nlprob::I, update_nlprob!::J, nlprobmap::K,
+            nlprobpmap::L) where {I, J, K, L}
+        return new{I, J, K, L}(nlprob, update_nlprob!, nlprobmap, nlprobpmap)
+    end
+end
+