Re: [Axiom-developer] bug #10063 overview: Handling of power series

[root]

Greg,

Well, I wasn't looking for a new bug to chase but this is clearly one.

The bug is actually in the algebra somewhere rather than in the lisp.
The NAG version fails with the error msg:

+++ Error attempt to take the car of an atom: 0

Did you file this in the axiom bug list?

Tim

====================================================================
Hi,

What do you think of this 'fatal 'bug?



It seems that the interpreter handles strangely the power series: 

a:= series sin(x); 
)di type % 
Type of value of %: UnivariatePuiseuxSeries(Expression Integer,x,0) 
a=a; 
)di type % 
Type of value of %: Equation Any 

If I coerce it... 
a:=a::UnivariatePuiseuxSeries(Expression Integer,x,0); 
a=a;
)di type % 
Type of value of %: Equation UnivariatePuiseuxSeries(Expression
Integer,x,0) 
------------------------------------------------ 
Fatal bug: 

a:= series sin(x); 
a*1.0; 
>> System error: 
Caught fatal error [memory may be damaged] 

protected-symbol-warn called with (NIL) 

>From trace: 
It seems that the interpreter doesn't coerce one args 
in Expression (Float): 

1<enter valueArgsEqual? : (|UnivariatePuiseuxSeries| (|Expression|
(|Integer|)) |x| ((0 . 0) 0 . 1))\(|UnivariatePuiseuxSeries|
(|Expression| (|Float|)) |x| ((0 . 0) 0 . 1)) 

... 

And here: 

1<enter algEqual : ((0 . 0) 0 . 1)\((0 0 . 0) 0 1 . 0)\(|Expression|
(|Float|)) 
1<enter compiledLookupCheck : =\((|Boolean|) $ $)\#<vector 08eccc78> 
1>exit compiledLookupCheck : (#<compiled-function |EXPR;=;2$B;21|> .
#<vector 08eccc78>) 

after SPADCALL (it's not traced) "=" in EXPR trigger the bug. 

algEqual : ((0 . 0) 0 . 1)\((0 0 . 0) 0 1 . 0)\(|Expression| (|Float|)) 
^^^^^^^^^^^^^^^ 
I think above is not of type EXPR FLOAT. 

Cheers, Greg