bugAxiom Computer Algebra System - Bugs: bug #9218, problems with output of D

 
 

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bug #9218: problems with output of D

Submitted by:  Martin Rubey <kratt6>
Submitted on:  Fri 04 Jun 2004 08:26:31 AM UTC  
 
Category:  None Severity:  3 - Normal
Item Group:  code bug Status:  None
Privacy:  Public Assigned to:  None
Originator Name:  kratt6 Open/Closed:  Open
Release:  tla from may 2004 Reproducibility:  None
Fixed Release: 
Error message: 
Example of code trigerring the bug: 

eval(D(f(x),x),f,y+->sum(g(i,y),i=a..y))

Internal cause: 

I think, the real internal cause is that axiom assumes that everything can be nicely differentiated, thus not providing a possibility of returning an unevaluated differential operator...

Also consider:
(13) -> D(f(x,x),x)

(13) f (x,x) + f (x,x)
,2 ,1
Type: Expression Integer

(which is correct)

Fri 04 Jun 2004 08:28:53 AM UTC, comment #1:

I forgot to add the following:

(17) -> eval(z,x,2)

(17) %defsum (g(%C),%C,i,a,2)
,5
Type: Expression Integer

is questionable (but may be interpreted correctly)

Martin

Martin Rubey <kratt6>
Fri 04 Jun 2004 08:26:31 AM UTC, original submission:

eval(D(f(x),x),f,y+->sum(g(i),i=a..y))

(9) %defsum (g(%A),%A,i,a,x)
,5

although this is correct, it looks rather strange...

Worse:

(12) -> eval(D(f(x),x),f,y+->sum(g(i,y),i=a..y))

(12) %defsum (g(%A,%%01),%A,i,a,x)
,5
Type: Expression Integer

Martin Rubey <kratt6>

 

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Depends on the following items: None found

Items that depend on this one: None found

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2008-11-25 axiom Internal causeI think, the real internal cause is that axiom assumes that everything can be nicely differentiated, thus not providing a possibility of returning an unevaluated differential operator... Also consider: (13) -> D(f(x,x),x) (13) f (x,x) + f (x,x) ,2 ,1 Type: Expression Integer (which is correct) => I think, the real internal cause is that axiom assumes that everything can be nicely differentiated, thus not providing a possibility of returning an unevaluated differential operator... Also consider: (13) -> D(f(x,x),x) (13) f (x,x) + f (x,x) ,2 ,1 Type: Expression Integer (which is correct)

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