Hello Luiz,

I would have loved the HP-55! Back then ('82) I had a TI-51-III (same as TI-55). I had just learned Calculus (or at least I thought I had :-) and knew no numerical methods at all, but I tried the very limited numerical integration program below. Those were the days!

Cheers,

Gerson.

00 RCL 16 2

01 1 17 RCL

02 * 18 3

03 RCL 19 +

04 2 20 1

05 f(x) ;(*) 21 =

06 = 22 STO

07 SUM 23 3

08 0 24 +/-

09 RCL 25 +

10 2 26 RCL

11 + 27 4

12 RCL 28 =

13 1 29 1/x

14 = 30 RST

15 STO
(*) f(x) is any of the following built-in functions:

sin, cos, tan, sinh, cosh, tanh, log, ln(x), e^x, 10^x, sqrt(x) or 1/x.

Usage:

n -> STO 4

(b-a)/n -> STO 1

(RCL 1)/2 + a -> STO 2

0 -> STO 0 STO 3

2nd RST 2nd R/S

when the program stops on error,

press CLR RCL 0 to get the result

Example:

Integrate f(x) = sin(x) from a = 0 rd to b = 1 rd, using n = 50 intervals, should return 0.4597054.

Actual result is 0.4596977 (1 - cos(1)).

*Edited: 31 Mar 2012, 9:21 p.m. *