Consider the following statements regarding a PID controller:
1) The error is multiplied by a negative (for reverse action) proportional constant P, and added to the current output.
2) The error is integrated (averaged) over a period of time, and then divided by a constant I, and added to the current control output.
3) The rate of change of the error is calculated with respect to time multiplied by another constant D, and added to the output.
Which of the above statements are correct