[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Octave-bug-tracker] [bug #33055] Serious problem with quadgk with exp(-
From: |
M. Badawy |
Subject: |
[Octave-bug-tracker] [bug #33055] Serious problem with quadgk with exp(-s.^2) from -Inf to 0 |
Date: |
Tue, 12 Apr 2011 07:05:02 +0000 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16 |
URL:
<http://savannah.gnu.org/bugs/?33055>
Summary: Serious problem with quadgk with exp(-s.^2) from
-Inf to 0
Project: GNU Octave
Submitted by: firstharmonic
Submitted on: Tue 12 Apr 2011 07:05:01 AM GMT
Category: None
Severity: 3 - Normal
Priority: 5 - Normal
Item Group: Incorrect Result
Status: None
Assigned to: None
Originator Name:
Originator Email:
Open/Closed: Open
Discussion Lock: Any
Release: 3.2.4
Operating System: GNU/Linux
_______________________________________________________
Details:
I got the following from the terminal:
>>> quadgk(@(s) exp(-s.^2), -Inf, 0)
ans = -0.24489
First, this is a positive function, so the answer can't be negative.
Second, the answer should be equal to: sqrt(pi)/2 = 0.88623.
Despite this problem, Octave gets the right answer for:
>>> quadgk(@(s) exp(-s.^2), -Inf, Inf)
ans = 1.7725 ( = sqrt(pi))
and
>>> quadgk(@(s) exp(-s.^2), 0, Inf)
ans = 0.88623 ( = sqrt(pi)/2)
In my research, I encountered the same problem when using quadgk with an even
integrand integrating from -Inf to 0.
Hope this helps.
_______________________________________________________
Reply to this item at:
<http://savannah.gnu.org/bugs/?33055>
_______________________________________________
Message sent via/by Savannah
http://savannah.gnu.org/
- [Octave-bug-tracker] [bug #33055] Serious problem with quadgk with exp(-s.^2) from -Inf to 0,
M. Badawy <=