F#, erlang and more - how in demand?

Question

Erlang

There was a great desire to get acquainted with one of the functional languages, primarily erlang and F#. But if there are some real applications for erlang (sometimes there are tasks of writing scalable and fault-tolerant systems as part of the work), then there are 0 ideas for F # so far.
In addition, in Moscow, we managed to find about three vacancies for each of the languages ​​(and both there and there they are indicated in the desired, not mandatory), so the question naturally arises - what's the point of teaching them?
Why F#? I heard that it is good for mathematics, and as part of self-education and as a hobby I am engaged in modeling dynamic systems, dynamic filtering (Kalman filter, how could it be without it), I would like to check if F# really simplifies writing such systems.
Basically the questions are:
What are some real use cases for F#?
To what extent is each of these languages ​​in demand on the market?
What are some good F# books?
Well, which language in general (not only of these two) is more suitable for modeling (except for Fortran and mathematical packages such as matlab)? (the question is not for the sake of a hollivar, just an opinion is really interesting. Therefore, I ask you to refrain from loud statements like *C# crap, learn Python*) (and in pursuit - is erlang suitable for modeling both in terms of usability (for example, write UL expansion matrices are straight hell or simpler), and in terms of speed?

Answer 1

Erlang does not like big and complex calculations. Its ideal use is to transfer bytes from one process to another with the implementation of simple logic. For more productive things, NIF libraries are connected to it, these are just C / c ++ libraries for more performance