(35S) Quick integration

[Roberto Volpi]

Taking advantage of the suggestion of Thomas Klemm, here a version for the HP35S of a programme for quick integral calculation using as algorithm Gaussian integration.

A few keystrokes are necessary but overall it is an advancement. It is in fact little more accurate and permits to evaluate integrals like that given in the example (∫(sinX/X) dx in interval [0,2] that may not be evaluated by the native HP35S integrator).

It assumes that LBL F contains the f(x) to be integrated in RPN mode without using X register)

NOTE: IT ALREADY INCLUDES ERRATA POINTED OUT BY THOMAS KLEMM.

LBL I
STO B
-
2
/
STO A
STO+B
.6
sqr root
*
STO C
RCL +B
XEQ F001
5
*
STO D
RCL B
RCL -C
XEQ F001
5
*
STO +D
RCL B
XEQ F001
8
*
RCL +D
RCL *A
-9
/
RTN

The integral in the examble should be

LBL F
SIN
last x
/
RTN

INSTRUCTIONS:

- Input lower and upper integral value as usual (in this case, press "0" "ENTER" "2"

- Press "XEQ I ENTER"

- result: 1.6054186216


Enjoy!