Calc Crash (Real and Virtual)
09-09-2016, 07:26 PM (This post was last modified: 09-09-2016 07:27 PM by toml_12953.)
Post: #1
 toml_12953 Senior Member Posts: 1,948 Joined: Dec 2013
Calc Crash (Real and Virtual)
When I run the following program to compute the Ackermann function, both the virtual and real calculators crash. I expected to get an error but not a crash.
Try running it for X=4 and Y=3

Tom L

Code:
FNA(M,N) BEGIN   IF M==0 THEN     RETURN N+1;   END;   IF N==0 THEN     RETURN FNA(M-1,1);   ELSE     RETURN FNA(M-1,FNA(M,N-1));   END; END; EXPORT ACKERMANN() BEGIN   WHILE 1==1 DO     PRINT();     INPUT({X,Y},{'X','Y'});     MSGBOX("Ackermann= "+FNA(X,Y));     GETKEY;   END; END;

Tom L
Cui bono?
09-09-2016, 08:24 PM
Post: #2
 Arno K Senior Member Posts: 463 Joined: Mar 2015
RE: Calc Crash (Real and Virtual)
Well, I don't think that the calculators crashes (or I stopped that too early well, after about 10 minutes), perhaps you will have a look at the table here., which says that the deeply recursive ackerman-function should provide a(4,3)=a(3, 2^65536-3) which is bigger than the estimated amount of atoms in universe. So it should provide an overflow error at some point.
Arno
09-09-2016, 10:15 PM
Post: #3
 toml_12953 Senior Member Posts: 1,948 Joined: Dec 2013
RE: Calc Crash (Real and Virtual)
(09-09-2016 08:24 PM)Arno K Wrote:  Well, I don't think that the calculators crashes (or I stopped that too early well, after about 10 minutes), perhaps you will have a look at the table here., which says that the deeply recursive ackerman-function should provide a(4,3)=a(3, 2^65536-3) which is bigger than the estimated amount of atoms in universe. So it should provide an overflow error at some point.
Arno

I know they should get an error, either overflow or out of memory or too many stack levels or something like that but they really do crash. The virtual calc exits and the real one restarts. This should never happen.

Tom L

Tom L
Cui bono?
09-09-2016, 10:49 PM
Post: #4
 Arno K Senior Member Posts: 463 Joined: Mar 2015
RE: Calc Crash (Real and Virtual)
How long did it run in the VC until it exits? After 30 minutes still running on mine.
Arno
09-15-2016, 10:54 AM
Post: #5
 cyrille de brébisson Senior Member Posts: 1,047 Joined: Dec 2013
RE: Calc Crash (Real and Virtual)
Hello,

I found a bug in the program.
the input functions should have the title as the 2nd arguement, not the {'X', 'Y'} list.

Cyrille

Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP.
09-15-2016, 11:48 AM
Post: #6
 Arno K Senior Member Posts: 463 Joined: Mar 2015
RE: Calc Crash (Real and Virtual)
(09-15-2016 10:54 AM)cyrille de brébisson Wrote:  Hello,

I found a bug in the program.
the input functions should have the title as the 2nd arguement, not the {'X', 'Y'} list.

Cyrille

Does not change anything, in my opinion ["Title"] means optional:
Syntax:
INPUT(var,[“title”], [“label”], [“help”], [reset_value], [initial_value])
INPUT({vars},[“titles”], [{“labels”}], [{“helps”}], [{reset_values}], [{initial_values}])
var -> {var_name, real, [{pos}]}
var -> {var_name, [allowed_types_matrix], [{pos}]}
var -> {var_name, {choose_items}, [{pos}]}

and, instead of 4 and 3, 3 and 4 runs fine.
Arno
09-15-2016, 01:41 PM
Post: #7
 toml_12953 Senior Member Posts: 1,948 Joined: Dec 2013
RE: Calc Crash (Real and Virtual)
(09-15-2016 10:54 AM)cyrille de brébisson Wrote:  Hello,

I found a bug in the program.
the input functions should have the title as the 2nd arguement, not the {'X', 'Y'} list.

Cyrille

It seems to work the way it is but, of course, you know way more about how the calculator works than I do. Would the following code be better? It includes a placeholder comma.

Code:
INPUT({X,Y},,{'X','Y'});

Tom L

Tom L
Cui bono?
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