RBE3001_hw3_matlab.m

function PID = discretePID (x)
%The array parameter should be in this form (kp, ki, kd, deltaT, prevErr, desired)
%x(1)-x(3) kp, ki, kd coefficients
%x(4)delta time needed to perform integration and differentiation
%x(5) previous error
%x(6) desired setpoint value 
%prevErr should be a global variable
    
    err = x(6)- x(5); %Error equals difference between desired setpoint and previous error
    integral += err*x(4);
    derivative = (err- x(5))/x(4); 
    PID = kp*err + ki*integral + kd*derivative; %PID calculation
    x(5) = err; %Make previous error current error
end