floats_as_bytes.cs

unsafe static byte[] DoublesToBytes(double[] value)
{
    var bytes = new byte[8*value.Length];
    fixed (byte* b = bytes)
    {
        for (int i = 0; i < value.Length; i++)
        {
            var v = value[i];
            *((int*)(b + 8*i)) = *(int*)&v;
            *((int*)(b + 8*i+4)) = *(((int*)&v) + 1);

            *((double*)(b + i*8)) = value[i];
        }
    }

    return bytes;
}

static unsafe double[] BytesToDoubles(byte[] data)
{
    var result = new double[data.Length / 8];
    fixed (byte* ptr = &data[0])
    {
        for (var i= 0; i < result.Length; i++)
        {
            result[i] = *((double*)(ptr + i * 8));
        }
    }
    return result;
}

var f = new[] { 1.23399996758d, 3.14, 0 };

byte[] bytes = DoublesToBytes(f);

Console.WriteLine(BitConverter.ToString(bytes));

foreach (var decoded in BytesToDoubles(bytes))
{
    Console.WriteLine(decoded);
}