Vladimir Bondarenko wrote:
> ----------------------------------------------------------------
>
> Our little demo continues..... Hello again from the VM machine
> which hopefully soon will not be ignored by CAS manufacturers.
>
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>
> N[Integrate[Sin[z] BesselJ[1, z]/Sqrt[z + z^2], {z,0,Infinity}]]
>
> 0.800192
This little demonstration illustrates how NOT to do re****ting of a bug.
Either there is an error in Integrate
or there is an error in N
or there are errors in both
or in neither.
It is possible for N[] to produce what appears to be a 'wrong' answer
because of limited precision resulting in excessive cancellation.
Whether this is wrong or not depends on what you expect N[] to do in
such cases.
It is possible for Integrate[] to produce an answer that is formally
correct but is in such a form as to cause massive cancellation, and thus
give the appearance that N is incorrect.
Someone posting a "bug" should specify whether this is the problem or not.
Perhaps the answer from Integrate is just clearly wrong, and N[] is the
simplest way to show that it is off the mark. In which case the person
presenting the bug should say so.
For example, does N[Simplify[Integrate[...]],1000] also produce the
same number, approximately?
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