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Re: inverse matrix
From: |
Mario Baussmann |
Subject: |
Re: inverse matrix |
Date: |
Mon, 17 Sep 2007 15:54:23 +0200 |
User-agent: |
Thunderbird 2.0.0.6 (Windows/20070728) |
Hi,
on my computer (WindowsXP):
Processors Information
------------------------------------------------------------------------------------
Processor 1 (ID = 0)
Number of cores 1
Number of threads 2 (max 2)
Name Intel Pentium 4
Codename Prescott
Specification Intel(R) Pentium(R) 4 CPU 2.80GHz
Package Socket 478 mPGA (platform ID = 2h)
CPUID F.3.4
Extended CPUID F.3
Core Stepping D0
Technology 90 nm
Core Speed 2799.7 MHz (14.0 x 200.0 MHz)
Rated Bus speed 799.9 MHz
Stock frequency 2800 MHz
Instructions sets MMX, SSE, SSE2, SSE3
L1 Data cache 16 KBytes, 8-way set associative, 64-byte line size
Trace cache 12 Kuops, 8-way set associative
L2 cache 1024 KBytes, 8-way set associative, 64-byte line size
FID/VID Control no
this script:
a = [1.2500e+02, 1.4595e+01, 5.8551e-08, 4.9222e+02; 1.4595e+01, \
1.0320e+01, -2.2343e-12, 1.7402e+02; 5.8551e-08, -2.2343e-12, \
5.8688e+03, -1.5056e-11; 4.9222e+02, 1.7402e+02, -1.5056e-11, \
8.8034e+03];
[x,rcond]=inverse(a)
produces with both versions 2.1.73 and 2.9.13 the same result for rcond:
6.5695...e-4.
regards
Mario
Ólafur Jens Sigurðsson schrieb:
Hi
I came across the following scenario:
For the following matrix
1.0634e-02 -7.5196e-03 -1.0610e-13 -4.4593e-04
-7.5196e-03 1.5066e-01 7.5071e-14 -2.5578e-03
-1.0610e-13 7.5071e-14 1.7039e-04 4.4484e-15
-4.4593e-04 -2.5578e-03 4.4484e-15 1.8909e-04
the inverse in version 2.9.10 in debian produces rcond = 0 but in 2.1.73
it is rcond = 0.00065696
Does this happen in all machines or is this just me (a AMD Athlon 1344
MHz, cpu family 6, model 8 ... info taken from /proc/cpuinfo running
debian unstable)?
If this is a general thing, is there a reason for why the 2.9.10 is
worse in this then 2.1.73 (I would consider this to be worse, unless
2.1.73 is just doing wrong calculation).
Regards
Oli
- inverse matrix, Ólafur Jens Sigurðsson, 2007/09/17
- Re: inverse matrix,
Mario Baussmann <=