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Re: Test fails - octave-2.1.20 on irix6.5
From: |
Joao Cardoso |
Subject: |
Re: Test fails - octave-2.1.20 on irix6.5 |
Date: |
Sat, 25 Mar 2000 17:26:19 +0000 |
"John W. Eaton" wrote:
>
> On 8-Nov-1999, Joao Cardoso <address@hidden> wrote:
>
> | "Billinghurst, David (RTD)" wrote:
> |
> | > Just built octave-2.1.20 on irix6.5 with both gcc-2.95.1 and egcs 19991102
> | > snapshot.
> | >
> | > I get a failure on test poly/residue-1.m as it misses the allowed
> tolerances
> | >
> | > by an order of magnitude. Haven't done a full error analysis, but I
> suspect
> | > the tolerances may be a little tight.
> | >
> | > The test case poly/residue-1.m is
> | >
> | > b = [1, 1, 1];
> | > a = [1, -5, 8, -4];
> | > [r, p, k, e] = residue (b, a);
> | > (abs (r - [-2; 7; 3]) < sqrt (eps)
> | > && abs (p - [2; 2; 1]) < sqrt (eps)
> | > && isempty (k)
> | > && e == [1; 2; 1])
> | >
> | > For octave-2.1.20 this fails as
> | >
> | > r - [-2; 7; 3] =
> | > -1.0658e-14
> | > 1.7276e-07
> | > 1.1990e-14
> | >
> | > while sqrt (eps) = 1.4901e-08
> |
> | I also have this problem with SCO. However the same test in
> | octave-2.1.14 runs OK.
>
> The roots function uses eig, and Lapack was updated to 3.0 for
> 2.1.20. Could that be the cause of the problem? It seems to work
> fine on my Linux system.
>
> jwe
Yes, the problem is in eig().
In 2.1.29:
octave:15> A=[ 5 -8 4; 1 0 0; 0 1 0]
A =
5 -8 4
1 0 0
0 1 0
octave:16> r = eig (A)
r =
2.00000
2.00000
1.00000
octave:17> r - [2 2 1]'
ans =
-6.1055e-08
6.1055e-08
-4.4409e-16
while in 2.1.14
octave:47> r
r =
2.00000 + 0.00000i
2.00000 - 0.00000i
1.00000 + 0.00000i
octave:48> p - [2 2 1]'
ans =
-6.6613e-16 + 5.4657e-08i
-6.6613e-16 - 5.4657e-08i
-7.7716e-16 + 0.0000e+00i
Matlab on an alpha with OSF1:
bash-2.01$ matlab
< M A T L A B >
Copyright 1984-1999 The MathWorks, Inc.
Version 5.3.1.29215a (R11.1)
Oct 6 1999
To get started, type one of these: helpwin, helpdesk, or demo.
For product information, type tour or visit www.mathworks.com.
>> A=[ 5 -8 4; 1 0 0; 0 1 0]
>> r = eig (A)
r =
2.0000 + 0.0000i
2.0000 - 0.0000i
1.0000
>> r - [2 2 1]'
ans =
1.0e-07 *
0.0000 + 0.2300i
0.0000 - 0.2300i
0.0000
And now my knowledge has finish... can this help?
Joao
--
Joao Cardoso, address@hidden
"Science is like sex: sometimes something useful comes out, but that is
not the reason we are doing it" -- Richard Feynman
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