It's mainly thought as a practical exercise for me to understand how a neural net works but will hopefully still be usable in later projects.

Number of input and output neurons, hidden layers and neurons in hiddenlayers plus bias can be specified. It tries to find the perfect weight as a double through "evolution".

Imagine you're a GOD!

Over time you have grown lonely and are hoping to find someone to talk to, a living creature with even a spec of inteligence would suffice. Some time ago, you created humans, although they should little potential at their current state. You set yourself a goal: Try to breed a single human, who could tell you wheter two bits are the same or not.

You start with a little village, you give everyone the same four tests: is 0 and 0, 0 and 1, 1 and 0, 1 and 1 the same?

Through your booming voice coming from the skies they hear your question (it enters their input neuron), they think very hard about it (in their hidden neurons), each member thinks about it in a different way, which was determined at birth through their DNA. Then each one answers each of your four tests (with their ouput neuron). For each right answer you give them a "fitness point", which helps you keep track of everyone's score.

After they all answered, you randomly choose two of them, the higher their fitness the higher the chances of getting chosen (roulette). You put them in a room, put some romantic music on and hope they create an offspring (crossover rate). If they do, they must die (you cruel god), if they don't, they become part of the next generation. There is also a small change that some background radiation will swap one random part of a new kids DNA with a random new one (mutation rate). Kids will think in a mixture of their parents way of thinking.

You repeat this step (only make adults fuck copulate, not the kids) until your new population has the same amount of members as your old one. Then ask them the questions. Then make a new generation. Repeat until you find someone capable of solving all your tests.

Congrats, you found a new soulmate!