How to perform crossover of double numbers in my GA implementation?

Question

In a few words, how do I:

• go from double to bits,
• then do the crossover (one point, two point),
• and go back to double

I can develop the roulette wheel selection. What I don't see clearly is how mixing two doubles might give me a "better" double. Is that completely random? If the "fittest" of my doubles and my "weakest" one combine, won't they produce a mid-point double?

Elaboration: Shortest distance from a point to this curve

EDIT 1: Without slowing down the program too much.

EDIT 2: I considered using a byte[], but I don't know if that would go against the genetic algorithm part.

Answer 1

This worked for me:

BitArray BAA1 = new BitArray(BitConverter.GetBytes(a1));
BitArray BAA2 = new BitArray(BitConverter.GetBytes(a2));

    for (int i = r.Next(0, 64); i > 0; i--)
            {
                temp = BAA1.Get(i);
                temp2 = BAA2.Get(i);

                BAA1.Set(i, temp2);
                BAA2.Set(i, temp);


                temp = BAB1.Get(i);
                temp2 = BAB2.Get(i);

                BAB1.Set(i, temp2);
                BAB2.Set(i, temp);
            }

        byte[] tempbytes = new byte[BAA1.Length];

        BAA1.CopyTo(tempbytes, 0);
        double baa1 = BitConverter.ToDouble(tempbytes, 0);

        BAA2.CopyTo(tempbytes, 0);
        double baa2 = BitConverter.ToDouble(tempbytes, 0);

baa1 and baa2 are the end products of the cross.