Sendin double precision numbers through serial?

I need to send double values from arduino but the more I go into solutions the more it gets complicated.

I guess I need to transform double data into byte array and then send 8 byte buffer.

Do anyone have already written code for this or have anyone done it before?

I guess I need to transform double data into byte array and then send 8 byte buffer.

Why do you guess that? Most Arduino's don't have 8 byte doubles.

In any case, are you sending the values as binary or as text?

If binary, a union is the way to go.

So if you just send a 4-byte value, what shows up?

Serial.write(doubleValue);
or
Serial.writeln(doubleValue);

native Arduino only support 32 bit floats as datatype,
I did experiments communicating 64 bit doubles to and from Arduino with success. I used Python to send a 64 bit double in binary format to Arduino. The Arduino captured the bytes and converted them to 32 bits float (thereby losing significant digits)

Check this page - Arduino Playground - IEEE754tools - which has some of the protocode
disclaimer: The code can still have bugs as it is not engineered extensively.

+1 for a union.

...R