HP 15C and INT(1/√(1-x),0,1)

[salvomic]

(11-26-2017 11:01 PM)Dieter Wrote:  What are the two ENTERs supposed to do?
They are not required.

hi Dieter, you are right!
Without the ENTER I get 1.9999 in iOS in about 2 min (1 min with SCI 4).
In hardware HP15C no result after 27 min now with your program.
I controlled that all was ok with ON/y^x procedure (all flags and -88.88.88.88.88), I reset also the continuous memory (ON/-) but the same with FIX 4, with FIX 2 I get 1.99 after about 3 mins

Quote:...
What display setting do you use here?
Remember, this setting directly influences the accuracy of the result – and thus the execution time.

Nothing, FIX 4. I thought there was something wrong in Reg but it seems not.

Quote:Set FIX 4, and the official HP emulator returns 1,9999 almost immediately.
FIX 6 already causes the emulator to run for a while... until it stops with Error 0.

ok here in iOS. Also SCI 4 got 1.9999 after 1 min.
However not in hardware: this is strange by me: FIX 4 and nothing happens after 27 min, also with SCI 4...

Quote:Answers to both questions can be found in the 15C Advanced Functions Handbook which explains the Integrate function in detail. Take a look at the graph near x=1 and you'll see why this integrand is not trivial and why you should not expect a plain 2. As x approaches 1 the function approaches infinity. The AFH shows how such cases can be handled.

It's always a good idea to start with a moderate display setting like SCI 2 or FIX 2 or maybe FIX 4. Higher settings may cause very long integration times, especially on a hardware 15C.

Dieter

Thanks! I'll look there. The integral isn't trial at all.

(11-26-2017 11:13 PM)peacecalc Wrote:  Hello Salvo,
try your little program LBL1 without step 03 and 05 (both ENTER).
...
Okay, Dieter was fast as flash, but I can't delete my post.

thanks a lot! also your contribute is important for me.

(11-27-2017 01:33 AM)Carsen Wrote:  Good evening (at least where I live)

I tested your integral on my (hardware) HP 50g. In exact mode, I receive the answer of 2 immediately. In approx. mode on the HP 50g with a fix of 4, I get 1.9999 in a matter of 3 to 4 minutes. I did not time it. I did not use the Equation Writer and I was in RPN mode. I used the integral function that is on the [TAN] key and I built the equation on the stack with RPN. It's fun.

well, in Exact in 50g I missed EVAL... Using it with EQN editor I get 2 immediatly, but with std setting in "number format" mode no luck after a few minutes. With FIX 4 I got the result 1.9999 in less than 3 min.

Quote:Next I tested your integral on my Dad's (hardware 1987) HP-15C. I entered the equation as such...

1.) LBL 1
2.) 1
3.) SWAP
4.) -
5.) SQRT
6.) 1/x
7.) RTN

I set the HP-15C to a fix of 2 and integrated the integral from 0 to 1. In a time of 2 minutes and 42 seconds, I got the answer of 1.99.

the same as the Dieter program, here: ok in iOS, nothing after various minutes in Hardware...

Quote:Then I set the 15C to a fix of 4 and attempted to integrate the integral again. In a time of 16 minutes and 28 seconds, I stopped the 15C and didn't get an answer as a result.

In fact!

Quote:I can't give any advice as I am not a proficient user of the HP-15C ONLY because I don't own one yet. But I hope my input on how I solved the integral on my calculators (and my Dad's) proved useful. Oh and I can help with the HP 50g. I would say I am a solid user of the machine.

thank you!
HP 50g is a very "big" machine, precise and solid, indeed. I like it (also I like the Prime).

Salvo