\START\
\COMMENT=Program file dated 06/28/93, 16:37
\NAME=DIFER
\FILE=DIFER.85P
ClLCD
Disp "USE LOWER CASE X"
InpSt "Y=",YS
\St>Eq\(YS,Y)
Disp "ENTER X VALUE"
Input B
Disp "ENTER dx"
Input dx
(der1(Y,x,B)*dx)\->\dY
Disp "dY= ",dY
evalF(Y,x,B)\->\C
Disp "f(x)=",C
evalF(Y,x,B+dx)-evalF(Y,x,B)\->\\UC-Delta\Y
Disp "\UC-Delta\Y= ",\UC-Delta\Y
dY/evalF(Y,x,B)\->\RELERR
Pause "HIT ENTER"

Disp "REL ERROR ="
Disp round(RELERR*100,2)
\STOP\