% PIPE FLOW TEMPERATURE CONTROL
  clear all
  ROLD=0.0;HOLD=0.0;SENSOR=ROLD;
  TARGET=5.0;LOAD=0.0;DUMP=10.0;      
  X=0.5;Y=1.0;A=0.1;B=1.0;Z=1.0;
  WRONG=TARGET-SENSOR;SUM=0.0;
  NIT=5000;MIT=200;TIME=0.0;
  GP=1.2;GI=1.2;GD=0.3;
  BAND=10; DELT=0.0025;     
  for IT=1:NIT
  TIME=TIME+DELT;     
  if(IT>MIT) ... 
   SENSOR=R(IT-MIT); end; 
  ERROR=TARGET-SENSOR;
  RATE=(ERROR-WRONG)/DELT;
  CONTROL=GP*ERROR;
  CONTROL=CONTROL+GI*SUM;      
  CONTROL=CONTROL+GD*RATE;
  if(abs(ERROR)<BAND) ...
  SUM=SUM+DELT*ERROR;end;
  if(CONTROL>DUMP) ...
   CONTROL=DUMP; end;
  if(CONTROL<0.0) ...  
   CONTROL=0.0; end; 
  ABC=Z*CONTROL-B*HOLD;
  XYZ=HOLD+LOAD-Y*ROLD;
  HNEW=HOLD+DELT*ABC/A;
  RNEW=ROLD+DELT*XYZ/X;
  T(IT)=TIME;R(IT)=RNEW;
  ROLD=RNEW;HOLD=HNEW;
  WRONG=ERROR;
  end; plot(T,R)
  xlabel('time')
  ylabel('volts')
  title('lab setup')