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[CAS bug, hang] Telescoping sums
08-07-2017, 09:25 PM (This post was last modified: 08-11-2017 09:27 AM by ettlz.)
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[CAS bug, hang] Telescoping sums
It appears HP Prime CAS 1.1.2-11 (fw 20170710, 12066) can't deal with simple telescoping sums, for example:
\[\sum_{n=1}^{\infty}\left(\frac1{n+1}-\frac1n\right) \rightarrow \text{undef}\]
This is a regression from the 50g.
returns \(-{\rm Psi}(1+a)+{\rm Psi}(2+a)-1\) and this simplifies to the expected \(-a/(1+a)\) (which the 50g returns immediately). Taking the limit \(a\rightarrow\infty\) works on the intermediate expression in terms of \({\rm Psi}\), but
hangs the Prime. The current Android app crashes.

The summations works OK in Xcas 1.2.3, so I presume a fix is queued for the next firmware update.
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