I'm trying to create a TikZ based version of the following diagram (taken from here), but I don't know how to approach it.
It doesn't need to look exactly like the original, but the basic idea should be preserved. It would especially be great if the paths from X_n to the sum function were straight lines without a "bend" like in the original. That makes a matrix layout difficult to use.
The definition of the output function can be left away.
Could someone point me to an approach that will work in this case, or even create a tikz texample?
Update: I ended up combining the approaches by @m0nhawk and @Toscho and came up with this:
Sourcecode is here: https://github.com/dbrgn/blog/blob/master/static/img/2013/3/26/perceptron.tex