HP 30b: Bug in Student function?

[Gerald H]

The probability function Student for 5 degrees of freedom & a t-score of 1.677 occasionally returns a false value of 0.869 & then, on somehow re-entering the input differently(?) occasionally returns a correct value of 0.9228.

I'm quite bemused by this erracity.

[John Smitherman]

Hi Gerald. I'm getting the correct answer consistently.

Which version of software are you running? Hold down the ON and PMT keys simultaneously and then arrow down 4 times.


John

[Gerald H]

(11-09-2014 03:36 PM)John Smitherman Wrote:  Hi Gerald. I'm getting the correct answer consistently.

Which version of software are you running? Hold down the ON and PMT keys simultaneously and then arrow down 4 times.


John

SW Version: 4 5 2010 2

[John Smitherman]

I'm running 5 4 2012 5. If you're able to flash your 30b contact Gene Wright for updated software.


John

[Gerald H]

(11-09-2014 05:30 PM)John Smitherman Wrote:  I'm running 5 4 2012 5. If you're able to flash your 30b contact Gene Wright for updated software.


John

Sadly I'm not in the position to reflash.

[Gerald H]

It would be little but some consolation to have a list of known bugs.

Thank you John for your consideration.

[Marcus von Cube]

(11-09-2014 06:00 PM)Gerald H Wrote:  

(11-09-2014 05:30 PM)John Smitherman Wrote:  I'm running 5 4 2012 5. If you're able to flash your 30b contact Gene Wright for updated software.


John

Sadly I'm not in the position to reflash.

The latter is going to change. :-)

@Gene (I hope he is reading this): Can you help us with the latest 30b firmware? Mine is still from 2011.

[ElectroDuende]

Add another here with the version from 2010...

Is there somewhere a diagram of the flahsing cable, either for RS-232 or USB? I'm quite proficient in electronics, so I don't think I'll have any problems to buid it.

I assume that the update process is the same described to convert it to WP34s, rigth?

Thanks in advance!

[Marcus von Cube]

(11-10-2014 10:14 AM)ElectroDuende Wrote:  I assume that the update process is the same described to convert it to WP34s, right?

Right!

[kkapkin]

(11-10-2014 07:41 AM)Marcus von Cube Wrote:  

(11-09-2014 06:00 PM)Gerald H Wrote:  Sadly I'm not in the position to reflash.

The latter is going to change. :-)

@Gene (I hope he is reading this): Can you help us with the latest 30b firmware? Mine is still from 2011.

+1

[Gerald H]

Returning to the original topic:

Try entering 5, Input, 1.677, Math, Down, Down, Input, Down, Down - I then see 9.22...., ie the correct answer.

Now try the same with = after the 1.677 - I now get 8.706...., ie the wrong answer.

OS Version is still 4 5 2010 2.

Can anyone corroborate behaviour or say it's been fixed in later versions?

[ElectroDuende]

(11-11-2014 10:27 AM)Gerald H Wrote:  Returning to the original topic:

Try entering 5, Input, 1.677, Math, Down, Down, Input, Down, Down - I then see 9.22...., ie the correct answer.

Now try the same with = after the 1.677 - I now get 8.706...., ie the wrong answer.

OS Version is still 4 5 2010 2.

Can anyone corroborate behaviour or say it's been fixed in later versions?

I can corroborate, with SW Version 4 5 2010 1

In fact, I only get the correct value if I go to math menu just after entering the 1.667 value, pressing nothing else. If I do any other key presses (INPUT, =, 4 "roll downs" or 2 "swaps") I get 8.706...

[Gerald H]

(11-11-2014 11:57 AM)ElectroDuende Wrote:  

(11-11-2014 10:27 AM)Gerald H Wrote:  Returning to the original topic:

Try entering 5, Input, 1.677, Math, Down, Down, Input, Down, Down - I then see 9.22...., ie the correct answer.

Now try the same with = after the 1.677 - I now get 8.706...., ie the wrong answer.

OS Version is still 4 5 2010 2.

Can anyone corroborate behaviour or say it's been fixed in later versions?

I can corroborate, with SW Version 4 5 2010 1

In fact, I only get the correct value if I go to math menu just after entering the 1.667 value, pressing nothing else. If I do any other key presses (INPUT, =, 4 "roll downs" or 2 "swaps") I get 8.706...

I observe the same behaviour.

AND if you then after 1.677 recall the flashing cursor by pressing the left arrow key, ie rightmost key of third row from top, the answer remains the same false value.

[kakima]

OS 4 5 2010 1

I also get the wrong answer if I do 5 1.677 STO 1 MATH etc.
Also the wrong answer with 5 RCL 1 MATH etc.

Now try it with a negative value for t.
5 -1.677 MATH etc gives the right answer.
Doing anything after the 7 (two swaps, STO, etc) gives Invalid Input.

This also seems to happen with other values for df and t (obviously, I haven't tried all possible combinations) except when df == t.

[Gerald H]

Thank you kakima for confirming the error & extending the range of values applicable.

Can anyone confirm that this behaviour has been corrected in later OS versions?

Is there any point in reflashing to some version supplied with a higher version number?

I can't see any source for OSs - certainly not from HP.

[kakima]

It's even worse. I seem to be getting similar results with the chi-square distribution.

I'm too depressed right now to try experimenting with the F distribution.

[Gerald H]

(11-12-2014 07:29 AM)kakima Wrote:  It's even worse. I seem to be getting similar results with the chi-square distribution.

I'm too depressed right now to try experimenting with the F distribution.

Yes, I confirm problem with Chi squared:

For D of F 5 & Chi squared value of 1.677 I get 1.08..... & after then spinning the stack down 4 times an "ER: Invalid Input Chi^2" notice.

[Gerald H]

(11-11-2014 10:27 AM)Gerald H Wrote:  Returning to the original topic:

Try entering 5, Input, 1.677, Math, Down, Down, Input, Down, Down - I then see 9.22...., ie the correct answer.

Now try the same with = after the 1.677 - I now get 8.706...., ie the wrong answer.

OS Version is still 4 5 2010 2.

Can anyone corroborate behaviour or say it's been fixed in later versions?

I'm pleased to say that, by hook or by crook & with the assistance of members of the forum, I now have an HP 30b version 5 4 2012 5.

Contrary to member John Smitherman's experience, on attempting the quoted procedure the calculator does NOT return the correct result consistently.

In fact the machine now prefers to report "Error:Invalid Input Student", a questionable improvement.

Whatever bugs may have been corrected remains a mystery to me.

[Dwight Sturrock]

I have the same version as Gerald. On my calc the ON + PMT key combo also seems to clear all user programs....

[Gerald H]

(01-02-2015 08:21 PM)Dwight Sturrock Wrote:  I have the same version as Gerald. On my calc the ON + PMT key combo also seems to clear all user programs....

ON+PMT does NOT affect my progs in either of my two versions.