WP 34S Modulo Bug
06-22-2014, 07:02 AM
Post: #1
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
WP 34S Modulo Bug
Try -4, 2, Mod

My 3.3T 3645 returns 2.
06-22-2014, 08:10 AM
Post: #2
 walter b On Vacation Posts: 1,957 Joined: Dec 2013
RE: WP 34S Modulo Bug
That's correct IMHO. Please compare p.67 of the printed manual.

d:-)
06-22-2014, 08:43 AM
Post: #3
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 08:10 AM)walter b Wrote:  That's correct IMHO. Please compare p.67 of the printed manual.

d:-)

Page 58 of electronic manual, example, 2nd line, substituting my values gives

-4/2= -2 + 1/2(-0).

Do you feel confirmed in your assertion?
06-22-2014, 09:04 AM
Post: #4
 HP67 Senior Member Posts: 686 Joined: Dec 2013
RE: WP 34S Modulo Bug

It ain't OVER 'till it's 2 PICK
06-22-2014, 10:44 AM (This post was last modified: 06-22-2014 10:46 AM by pito.)
Post: #5
 pito Member Posts: 131 Joined: Jun 2014
RE: WP 34S Modulo Bug
(06-22-2014 08:43 AM)Gerald H Wrote:  Page 58 of electronic manual, example, 2nd line, substituting my values gives

-4/2= -2 + 1/2(-0).

Do you feel confirmed in your assertion?

That is a formula for a division in the integer mode, not for a mod..

PS: I think -4 mod 2 shall be 0..
06-22-2014, 10:48 AM
Post: #6
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 10:44 AM)pito Wrote:
(06-22-2014 08:43 AM)Gerald H Wrote:  Page 58 of electronic manual, example, 2nd line, substituting my values gives

-4/2= -2 + 1/2(-0).

Do you feel confirmed in your assertion?

That is a formula for a division in the integer mode, not for a mod..

PS: I think -4 mod 2 shall be 0..

Thank you Pito for your interest, but would you say two numbers can have a remainder of zero & non-zero modulo?
06-22-2014, 10:53 AM (This post was last modified: 06-22-2014 10:55 AM by pito.)
Post: #7
 pito Member Posts: 131 Joined: Jun 2014
RE: WP 34S Modulo Bug
(06-22-2014 10:48 AM)Gerald H Wrote:
(06-22-2014 10:44 AM)pito Wrote:  That is a formula for a division in the integer mode, not for a mod..

PS: I think -4 mod 2 shall be 0..

Thank you Pito for your interest, but would you say two numbers can have a remainder of zero & non-zero modulo?
As I wrote above, the -4 mod 2 shall be 0.
Afaik "mod function is defined as the amount by which a number exceeds the largest integer multiple of the divisor that is not greater than that number.."
06-22-2014, 10:54 AM
Post: #8
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 09:04 AM)HP67 Wrote:  -4 mod 2 @ Wolfram

Thank you for the reference.

But surely Walter B's contention can be confirmed(?) by a reference, as indeed he has to himself. Your ref has the doubtful advantage of not having been written by yourself.

A battle of authorities or some careful thought?
06-22-2014, 10:55 AM
Post: #9
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 10:53 AM)pito Wrote:
(06-22-2014 10:48 AM)Gerald H Wrote:  Thank you Pito for your interest, but would you say two numbers can have a remainder of zero & non-zero modulo?
As I wrote above, the -4 mod 2 shall be 0.

Indeed.
06-22-2014, 10:56 AM
Post: #10
 Paul Dale Senior Member Posts: 1,834 Joined: Dec 2013
RE: WP 34S Modulo Bug
Are you sure you shouldn't be using the RMDR operation? -4 2 RMDR gives 0.

MOD and RMDR differ in their processing of negative values. The former being added late for compatibility with the 41 series devices.

- Pauli
06-22-2014, 11:18 AM
Post: #11
 HP67 Senior Member Posts: 686 Joined: Dec 2013
RE: WP 34S Modulo Bug
(06-22-2014 10:54 AM)Gerald H Wrote:
(06-22-2014 09:04 AM)HP67 Wrote:  -4 mod 2 @ Wolfram

Thank you for the reference.

But surely Walter B's contention can be confirmed(?) by a reference, as indeed he has to himself. Your ref has the doubtful advantage of not having been written by yourself.

A battle of authorities or some careful thought?

My HP 48 and HP 50g also show a result of zero. If the answer isn't zero, then there are going to be a lot more upset people (HP and Wolfram customers) than WP 34S customers

It ain't OVER 'till it's 2 PICK
06-22-2014, 11:32 AM
Post: #12
 Massimo Gnerucci Senior Member Posts: 2,648 Joined: Dec 2013
RE: WP 34S Modulo Bug
(06-22-2014 10:56 AM)Paul Dale Wrote:  Are you sure you shouldn't be using the RMDR operation? -4 2 RMDR gives 0.

MOD and RMDR differ in their processing of negative values. The former being added late for compatibility with the 41 series devices.

- Pauli

4 CHS ENTER^ 2 XEQ 'MOD
gives 0 on the 41

Greetings,
Massimo

-+×÷ ↔ left is right and right is wrong
06-22-2014, 11:33 AM
Post: #13
 pito Member Posts: 131 Joined: Jun 2014
RE: WP 34S Modulo Bug
(06-22-2014 10:56 AM)Paul Dale Wrote:  MOD and RMDR differ in their processing of negative values.
- Pauli
That is true, however

Y mod X = 0 for any positive/negative X or Y where Y = k * X, and k is an integer.
06-22-2014, 12:25 PM
Post: #14
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 10:56 AM)Paul Dale Wrote:  Are you sure you shouldn't be using the RMDR operation? -4 2 RMDR gives 0.

MOD and RMDR differ in their processing of negative values. The former being added late for compatibility with the 41 series devices.

- Pauli

Very interesting.

So you propose an operating system where a zero remainder corresponds to a non-zero result modulo?
06-22-2014, 12:30 PM
Post: #15
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 11:33 AM)pito Wrote:
(06-22-2014 10:56 AM)Paul Dale Wrote:  MOD and RMDR differ in their processing of negative values.
- Pauli
That is true, however

Y mod X = 0 for any positive/negative X or Y where Y = k * X, and k is an integer.

Much better, an appeal to a definition!

You may by now be wondering how proficient in arithmetic some of the correspondents are.
06-22-2014, 12:33 PM
Post: #16
 jebem Senior Member Posts: 1,355 Joined: Feb 2014
RE: WP 34S Modulo Bug
(06-22-2014 11:18 AM)HP67 Wrote:
(06-22-2014 10:54 AM)Gerald H Wrote:  Thank you for the reference.

But surely Walter B's contention can be confirmed(?) by a reference, as indeed he has to himself. Your ref has the doubtful advantage of not having been written by yourself.

A battle of authorities or some careful thought?

My HP 48 and HP 50g also show a result of zero. If the answer isn't zero, then there are going to be a lot more upset people (HP and Wolfram customers) than WP 34S customers

My HP-PRIME returns Zero for the -4 MOD 2 expression as well.

Jose Mesquita

06-22-2014, 12:34 PM
Post: #17
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
Meanwhile I believe the problem is in psychology.

The poor MOD function is the only function singled out in the manual as existing "unfortunately"!

Clearly Euler & Gauss preferred modulo to remainder; Newton was ambiguous, but never actually disparaging of modulo. I would rather discount Fermat's well-known antipathy to modulo as a quirk, shared by a die-hard few even today.
06-22-2014, 12:35 PM
Post: #18
 HP67 Senior Member Posts: 686 Joined: Dec 2013
RE: WP 34S Modulo Bug
(06-22-2014 12:33 PM)jebem Wrote:
(06-22-2014 11:18 AM)HP67 Wrote:  My HP 48 and HP 50g also show a result of zero. If the answer isn't zero, then there are going to be a lot more upset people (HP and Wolfram customers) than WP 34S customers

My HP-PRIME returns Zero for the -4 MOD 2 expression as well.

Yes, it's certainly zero as we all know. Unfortunately those who tried to support the OP were regarded unfavorably by that very same person we sought to help.

It ain't OVER 'till it's 2 PICK
06-22-2014, 12:36 PM
Post: #19
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
(06-22-2014 12:33 PM)jebem Wrote:
(06-22-2014 11:18 AM)HP67 Wrote:  My HP 48 and HP 50g also show a result of zero. If the answer isn't zero, then there are going to be a lot more upset people (HP and Wolfram customers) than WP 34S customers

My HP-PRIME returns Zero for the -4 MOD 2 expression as well.

Thank you for the reference.

Inability to acknowledge an overt error makes me wonder whether other bug reports have been so disparagingly treated.
06-22-2014, 12:38 PM
Post: #20
 Gerald H Senior Member Posts: 1,627 Joined: May 2014
RE: WP 34S Modulo Bug
So that's it? An obvious error will be passed over & the operating system remains defect?
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