08-07-2017, 09:25 PM
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.
\[\sum_{n=1}^{a}\left(\frac1{n+1}-\frac1n\right)\]
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
\[\lim_{a\rightarrow\infty}\sum_{n=1}^{a}\left(\frac1{n+1}-\frac1n\right)\]
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.
\[\sum_{n=1}^{\infty}\left(\frac1{n+1}-\frac1n\right) \rightarrow \text{undef}\]
This is a regression from the 50g.
\[\sum_{n=1}^{a}\left(\frac1{n+1}-\frac1n\right)\]
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
\[\lim_{a\rightarrow\infty}\sum_{n=1}^{a}\left(\frac1{n+1}-\frac1n\right)\]
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.