How to solve PID Equation

Hello Friends,

e is 4

previous Error is 5

kp is 0.1

kd is 0.1

ki is 0.1

dt is 0.001

how to apply above value in PID Equation and what is the u(t).

u(t)=kp* e(t) + ki * ∫ e(t) + kd * de(t)/dt

why integral error is called as past error, and Derivative Error is Called as future error, proportional yes i understood its present error we multiplying by kp.

pseudo code

Derivative error is calculated by

Error= (Error-Previous Error)/time --> how this will predict future error

Note: I have little difficulty in understanding calculus