Re: can't calculate integral on hp 41 Message #4 Posted by Luiz C. Vieira (Brazil) on 15 May 2012, 3:36 p.m., in response to message #3 by Hans Holzach
Hallo, Hans.
Allow me to add a few remarks.
You are correct, after pressing ENTER you duplicate the X-register contents into Y-register. But as you have the PI entered in the stack right after ENTER - so stack lift is disabled - then you will still have a single copy of the X-register contents into the Y-register. So, when × (multiplication) after PI is performed, the Y-register contents return to its original value.
In fact this is irrelevant for the HP15C's integral computation because the integral function itself fills the stack registers with the same value, teh one your custom function will be evaluated for, before calling it, so you do not need to worry about stack contents. IIRC, the HP41 Math Pac integral program does the same, i.e., the stack is filled with the number to evaluate, that's why the integral program works fine. If you want to evaluate the program for a single value, you simply fill the stack registers with and run it.
The major difference between the HP15C (and the other Voyagers) in relation to the HP41 is that numbers keyed in as program lines do not terminate digit entry. If you need further explanation about this let me know, it is not relevant related to this subject.
Cheers.
Luiz (Brasilien)
Edited: 15 May 2012, 3:38 p.m.
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