Thanks.  I'll review your previous email in more detail.

On 17 March 2015 at 02:48, Waldek Hebisch <[email protected]> wrote:
> Bill Page wrote:
>>
>> The following sequence of commands:
>>
>> --
>> integrate(sin(sqrt(x*x)),x)
>> )trace INTEF )math
>> integrate(sin(sqrt(x*x)),x)
>> )trace INTEF )off
>> integrate(sin(sqrt(x*x)),x)
>> D(%,x)
>> %-sin(sqrt(x*x))
>> normalize %
>> --
>>
>> produces unexpected results.  For example:
>>
>> http://axiom-wiki.newsynthesis.org/SandBoxTraceAffectsResults
>>
>> I get slightly different but still wrong results in different versions
>> of FriCAS.
>
> I get error already when computing last integral.  This probably
> is the same problem that I described with subject 'Troubles with
> kernels'.  I consider this a bug...
>
> More precisely, ')trace' seem to cause no troubles.  However
> ')untrace' causes re-evaluation of 'Expression' and 'Kernel'.
> From one point of view re-evaluation is reasonable.  But in this
> case apparently we get a kernel entered in old cache and assigned
> a position.  Then we create a new cache and for new kernels
> use positions in new chache.  This is incorrect, becuse comparisons
> of kernels compare positions.  Of course postions in old cache
> and new one are independent and we get all kind of weird things
> like x which is not equal to x.
>
> ATM doing ')clear completely' after ')untrace' seems to
> get rid of the problem.
>

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