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hi,
there is a way in Prime to do this sum?
$\sum_{k=1}^{\infty}{\frac {(-1)^{k+1}}{k^{2}} }$

the value is $$\frac {π^{2}}{12}$$

HP Prime gives symbolic form, not the value of the sum...

Thanks

Salvo
Same problem in xcas and Maxima. Wolframalpha gives the right answer.
(02-06-2015 04:47 PM)retoa Wrote: [ -> ]Same problem in xcas and Maxima. Wolframalpha gives the right answer.

yes, in fact!
As I like much more Prime (and HP 50g), I wonder why they don't...
(02-06-2015 02:26 PM)salvomic Wrote: [ -> ]hi,
there is a way in Prime to do this sum?
$\sum_{k=1}^{\infty}{\frac {(-1)^{k+1}}{k^{2}} }$

the value is $$\frac {π^{2}}{12}$$

HP Prime gives symbolic form, not the value of the sum...

Thanks

Salvo

You can do

$\sum_{k=1}^{\infty}{\frac {-1}{(2*k)^{2}} } + \sum_{k=1}^{\infty}{\frac {1}{(2*k-1)^{2}} }$

By the way I get the correct answer on the HP50G but my Prime seems unable to calculate Psi(1/2,1) in a numeric value.

I get :

1/4*Psi(1/2,1)-Pi²/24

Same on 50G then ->NUM returns 0.8224...
On the Prime ~ don't 'solve' Psi(0.5,1) . Strange ...
I also tried to decompose it in

$$\sum_{k=1}^{\infty}(\frac{1}{(2k-1)^2}-\frac{1}{(2k)^2})$$

to avoid the (-1)^(k+1), but I did not get the wanted result. Still the Psi(1/2,1)
(02-06-2015 05:08 PM)Gilles Wrote: [ -> ]You can do

$\sum_{k=1}^{\infty}{\frac {-1}{(2*k)^{2}} } + \sum_{k=1}^{\infty}{\frac {1}{(2*k-1)^{2}} }$

By the way I get the correct answer on the HP50G but my Prime seems unable to calculate Psi(1/2,1) in a numeric value.

thanks a lot, Gilles,
yes I see that Prime don't approx Psi1/2,1); my HP50 does it.

Hope in a next firmware to have the symbolic result (π^2/12), more interesting than Psi()
Indeed, for the approx value of Psi(x,1), Xcas calls the GSL, that is not available on the Prime.
(02-06-2015 06:55 PM)parisse Wrote: [ -> ]Indeed, for the approx value of Psi(x,1), Xcas calls the GSL, that is not available on the Prime.

I understand.
There is no other way to approximate Psi on Prime?

thank you
No built-in yet. Maybe I'll implement something, in the meantime you can write a user program
http://people.math.sfu.ca/~cbm/aands/page_260.htm
(02-07-2015 06:46 AM)parisse Wrote: [ -> ]No built-in yet. Maybe I'll implement something, in the meantime you can write a user program
http://people.math.sfu.ca/~cbm/aands/page_260.htm

ok, thank you for information!
I'll think to write a program, maybe...
the problem is now solved with the firmware 7820!