Matrix (linear map function) exponential multiplied with vector in ExponentialUtilities.jl

[stevengj]

@eveningsilverfox

Any ideas on how to implement it correctly? In reality I deal with massive matrices, which I must apply with the function above as they are very sparse. So I cannot use the actual matrices. The example provided here is only a representative case, not the actual matrix I use.

I think it’s expecting a “matrix-like” object that supports a size method, not just a function. However, you can wrap a “matrix-like” object around your function with LinearMaps.jl, in particular with LinearMap(x->matmap(x,aa,bb), Nx) which creates an object that has size == (Nx, Nx).