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Re: Novice question on A \ b
From: |
John B. Thoo |
Subject: |
Re: Novice question on A \ b |
Date: |
Fri, 11 Mar 2005 06:07:33 -0800 |
On Mar 11, 2005, at 5:41 AM, Przemek Klosowski wrote:
octave:18> A = [ [1, 1, 2, 3]' [0, 0, 4, 4]']; b = [3, 0, -1, 0]';
A \ b
ans =
1.40000
-1.00000
I think this is the minimum norm solution, but Octave did not issue
a warning. What is wrong with my thinking?
You didn't say what value of 'b' you used; I tried
b=[1.4 1.4 -1.2 .2]' and got the same result as you.
For what it is worth, so did the other leading brand.
I used b = [3, 0, -1, 0]'.
The documentation on Arithmetic Operators says about the left division:
If the system is not square, or if the coefficient matrix is
singular, a minimum norm solution is computed.
so no warning is indicated. Where did you see the warning mentioned?
I didn't see that notice (about non-square systems). This is the part
of the doc that I had read:
<http://www.octave.org/doc/octave_2.html#SEC10>
Cheers.
---John.
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