# Infinite loop calculating a series value - Hewlett Packard

This is a discussion on Infinite loop calculating a series value - Hewlett Packard ; I'm trying to calculate the value of this expresion: ABS(\sum(K=1, \infty, ((1+i)/2)^k)) the result should be 1 but my calculator enter in a infinite loop. How can I fix it? Thank you, bye....

# Thread: Infinite loop calculating a series value

1. ## Infinite loop calculating a series value

I'm trying to calculate the value of this expresion:

ABS(\sum(K=1, \infty, ((1+i)/2)^k))

the result should be 1 but my calculator enter in a infinite loop. How
can I fix it?

Thank you, bye.

2. ## Re: Infinite loop calculating a series value

On Mon, 10 Mar 2008 09:26:58 -0500, mambro wrote:

> I'm trying to calculate the value of this expression:
> ABS(sum(K=1,infinity,((1+i)/2)^k))
> the result should be 1

> my calculator enters an infinite loop.

An explicit sum of an infinite number of terms will tend to do that.

You could replace "infinity" by 100, say, or else use a limit:

First do command CASCFG, then:

'\GS(k=1,x,((1+i)/2)^k)'
EVAL SIMPLIFY
'x=+\oo'
LIMIT

Result: 'i'

Note that ABS(i) is 1

[r->] [OFF]

3. ## Re: Infinite loop calculating a series value

On Mar 11, 1:26 am, mambro wrote:
> I'm trying to calculate the value of this expresion:
>
> ABS(\sum(K=1, \infty, ((1+i)/2)^k))
>
> the result should be 1 but my calculator enter in a infinite loop. How
> can I fix it?
>
> Thank you, bye.

It's not an infinite loop. The calculator is doing the right thing.
You've been impatient. Next time sit down and wait until some thing
starts counting down from infinity. Meanwhile you can kill time asking
funny questions

4. ## Re: Infinite loop calculating a series value

On Mar 12, 10:47 pm, reth wrote:
> On Mar 11, 1:26 am, mambro wrote:
>
> > I'm trying to calculate the value of this expresion:

>
> > ABS(\sum(K=1, \infty, ((1+i)/2)^k))

>
> > the result should be 1 but my calculator enter in a infinite loop. How
> > can I fix it?

>
> > Thank you, bye.

>
> It's not an infinite loop. The calculator is doing the right thing.
> You've been impatient. Next time sit down and wait until some thing
> starts counting down from infinity. Meanwhile you can kill time asking
> funny questions

that's rather "ends counting down" not "starts"

5. ## Re: Infinite loop calculating a series value

On Mar 10, 9:26 am, mambro wrote:
> I'm trying to calculate the value of this expresion:
>
> ABS(\sum(K=1, \infty, ((1+i)/2)^k))
>
> the result should be 1 but my calculator enter in a infinite loop. How
> can I fix it?
>
> Thank you, bye.

I don't have my HP49G+ with me at the moment, but you could try:

ABS(\sum(K=1, \infty, a^k))

and substitute a=(1+i)/2 afterwards. If that example also hangs, then
the expected value of the sum is a/(1-a).

You should report the hang as a bug, although I'm not sure where
HP49/50 bugs are tracked nowadays.

Bhuvanesh