Infinite sum wrong result. Bug in Giac?
|
12-29-2014, 01:55 AM
Post: #1
|
|||
|
|||
Infinite sum wrong result. Bug in Giac?
Hi all,
I was reading this bug report for the 50g http://bugs.hpcalc.org/show_bug.cgi?id=238 and entered the same sum into the Prime for testing: sum from k=1 to infinity (((1+i)/2)^k) the Prime gives me 0 as the result. CAS mode, Settings: Exact on, Complex off (turning it on doesn't change the result), Use sqrt on, Use i on. I can also reproduce this in Giac/Xcas: `sum(((1+i)/2)^k, k=1...+infinity)` gives me 0 as well. In contrast, WolframAlpha says the result is i http://www.wolframalpha.com/input/?i=sum...o+infinity Trying a few finite upper boundaries on the Prime suggests that Wolfram Alpha is correct, and Giac/Prime are wrong. |
|||
12-29-2014, 01:58 AM
Post: #2
|
|||
|
|||
RE: Infinite sum wrong result. Bug in Giac?
Versions:
HP Prime 2014 12 3 (6975) xcas 1.1.3 |
|||
12-29-2014, 02:49 AM
(This post was last modified: 12-29-2014 03:40 AM by Helge Gabert.)
Post: #3
|
|||
|
|||
RE: Infinite sum wrong result. Bug in Giac?
Confirmed.
And, by the same token, sum from k=1 to infinity (((1-i)/2)^k) should return -i, but the Prime also thinks it is zero. [Edit: Also checked sum from k=1 to infinity (((-1+i)/2)^k) should return -2/5+i/5, but the Prime returns -2/5. Ditto sum from k=1 to infinity (((-1-i)/2)^k) should return -2/5-i/5, but the Prime returns -2/5 only.] |
|||
12-29-2014, 09:20 AM
Post: #4
|
|||
|
|||
RE: Infinite sum wrong result. Bug in Giac?
Fixed in source, thanks.
|
|||
12-30-2014, 04:07 AM
Post: #5
|
|||
|
|||
RE: Infinite sum wrong result. Bug in Giac?
Thanks for the super quick fix Bernard!
Let's see when we get it for the Prime... |
|||
« Next Oldest | Next Newest »
|
User(s) browsing this thread: