Difference Quotient - Casio 9800

This program estimates the value of a derivative at a point using the difference quotient   $f^\prime(A)\approx{f(A+H)-f(A)\over H}$
If you have not used one of the programs posted on this website before, you should read through the information in the Intro to Programming section first.

The Program
'DIFFQUO' {'   is in ALPHA} {This is the name of the program}
Lbl 1 {Lbl is in PRGM under JMP}
"A"?X {" is in ALPHA} {?   is in PRGM} { is on the   ,   button}
Y1B {Y1 is in VAR under GPH, then followed by a 1}
(C-B) HD
D        { is in PRGM}
Goto 1 {Goto is in PRGM under JMP}

Running the Program
You will need to enter a function f(x) into Y1 before running the program. To test the program try the following:
f(x)  =  x3,   A=2,   H=0.01.
The answer should be 12.0601