DAESystem

DAESystem(input, output, statefunc, outputfunc, state, stateder, t, modelargs=(), solverargs=(); 
    alg=DAEAlg, modelkwargs=NamedTuple(), solverkwargs=NamedTuple())

Construsts a DAESystem with input and output. statefunc is the state function and outputfunc is the output function. state is the initial state, stateder is the initial state derivative and t is the time. modelargs and modelkwargs are passed into ODEProblem and solverargs and solverkwargs are passed into solve method of DifferentialEquations. alg is the algorithm to solve the differential equation of the system.

DAESystem is represented by the following equations.

where $t$ is the time t, $x$ is state, $dx$ is the value of the derivative of the state stateder, $u$ is the value of input and $y$ is the value of output at time $t$. solver is used to solve the above differential equation.

The signature of statefunc must be of the form

function statefunc(out, dx, x, u, t)
    out .= ... # Update out
emd

and the signature of outputfunc must be of the form

function outputfunc(x, u, t)
    y = ... # Compute y 
    return y
end

Example

julia> function sfunc(out, dx, x, u, t)
           out[1] = x[1] + 1 - dx[1]
           out[2] = (x[1] + 1) * x[2] + 2
       end;

julia> ofunc(x, u, t) = x;

julia> x0 = [1., -1];

julia> dx0 = [2., 0.];

julia> ds = DAESystem(nothing, Bus(1), sfunc, ofunc, x0, dx0, 0., modelkwargs=(differential_vars=[true, false],))
DAESystem(state:[1.0, -1.0], t:0.0, input:nothing, output:Bus(nlinks:1, eltype:Link{Float64}, isreadable:false, iswritable:false))