DiffEqArrayOperator is missing

General Usage
2

It was archived a long time back in favor of SciMLOperators:

MatrixOperator is the version from there:

using DifferentialEquations
function update_func(A, u, p, t)
    A[1, 1] = cos(t)
    A[2, 1] = sin(t)
    A[1, 2] = -sin(t)
    return A[2, 2] = cos(t)
end
A = MatrixOperator(ones(2, 2); update_func=update_func)
prob = ODEProblem(A, ones(2), (10, 50.0))