[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Inverse Matrix Function appears a bit wonky
From: |
Mike Miller |
Subject: |
Re: Inverse Matrix Function appears a bit wonky |
Date: |
Fri, 5 Nov 2004 12:35:26 -0600 (CST) |
On Fri, 5 Nov 2004, Przemek Klosowski wrote:
OK, the official results are in: 3x3 {0..9}-valued matrices it's 4%, and
2% for 4x4 matrices, and .5% for 5x5 matrices. Funny. The originator of
this thread had 1-in-60 chance of picking a singular matrix.
I can tell you one thing for certain - people aren't good at generating
random numbers (my PhD is in psychology and this is a topic we
occasionally discuss). Anyway, it seems like people will often try to
make a 4x4 matrix and they'll start with something like this:
1 1
1 2
1 3
1 4
If they start with that, and have to use only integers 1-4 for the
remaining two columns, then what are their chances of getting a singular
matrix? (Assume they can choose numbers randomly, even though they
can't.) I think the probability is much higher than 4%. The human
tendency toward nonrandomness is what throws things off.
By the way, the classic example of human inability to generate random
patterns is seen when you ask people to generate a series of mental coin
tosses. They tend not to give you strings of 5 or 6 consecutive heads and
they give you too much alternation: HTHTHT. But HHHHHH and HTHTHT have
the same probability. It can make a fun classroom presentation.
Mike
-------------------------------------------------------------
Octave is freely available under the terms of the GNU GPL.
Octave's home on the web: http://www.octave.org
How to fund new projects: http://www.octave.org/funding.html
Subscription information: http://www.octave.org/archive.html
-------------------------------------------------------------
- Re: Inverse Matrix Function appears a bit wonky, (continued)
Re: Inverse Matrix Function appears a bit wonky, Geraint Paul Bevan, 2004/11/03
- Re: Inverse Matrix Function appears a bit wonky, Dmitri A. Sergatskov, 2004/11/03
- Re: Inverse Matrix Function appears a bit wonky, Geraint Paul Bevan, 2004/11/03
- Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Geraint Paul Bevan, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/03
- Re: Lapack issues? (Was Re: Inverse Matrix Function appears a bit wonky), Dmitri A. Sergatskov, 2004/11/04
Re: Inverse Matrix Function appears a bit wonky, Przemek Klosowski, 2004/11/05