S.O.S. Mathematics CyberBoard

Your Resource for mathematics help on the web!
It is currently Sat, 18 May 2013 21:46:36 UTC

View unanswered posts | View active topics


Board index » High School and College Mathematics » Matrix Algebra

All times are UTC [ DST ]



Post new topic Reply to topic  Page 1 of 1
  [ 8 posts ] 
  Print view Previous topic | Next topic 
Author Message
lyradmil
 Post subject: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Wed, 15 Feb 2012 09:23:22 UTC 
Offline
S.O.S. Newbie

Joined: Wed, 15 Feb 2012 09:20:23 UTC
Posts: 1
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix
Top
 Profile  
 
Justin
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Wed, 15 Feb 2012 14:35:24 UTC 
Offline
Member of the 'S.O.S. Math' Hall of Fame
User avatar

Joined: Wed, 21 May 2003 04:27:18 UTC
Posts: 988
lyradmil wrote:
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix


Socks and shoes?

_________________
"Mathematicians are like lovers. Grant a mathematician the least principle, and he will draw from it a consequence which you must also grant him, and from this consequence another." Bernard Le Bovier Fontenelle (1657-1757)

"In great mathematics there is a very high degree of unexpectedness, combined with inevitability and economy."
G.H. Hardy (1877-1947)
Top
 Profile  
 
Shadow
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Wed, 15 Feb 2012 15:10:54 UTC 
Online
Moderator
User avatar

Joined: Wed, 30 Mar 2005 04:25:14 UTC
Posts: 12074
Location: Austin, TX
Justin wrote:
lyradmil wrote:
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix


Socks and shoes?


What?

_________________
(\ /)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination
Top
 Profile  
 
Shadow
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Wed, 15 Feb 2012 15:11:55 UTC 
Online
Moderator
User avatar

Joined: Wed, 30 Mar 2005 04:25:14 UTC
Posts: 12074
Location: Austin, TX
lyradmil wrote:
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix


C^{-1} may or may not exist depending on the diagonal matrix, D. Assuming D is invertible, then you just need to invert both sides and recall that (AB)^{-1}=B^{-1}A^{-1}

_________________
(\ /)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination
Top
 Profile  
 
Justin
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Thu, 16 Feb 2012 15:29:46 UTC 
Offline
Member of the 'S.O.S. Math' Hall of Fame
User avatar

Joined: Wed, 21 May 2003 04:27:18 UTC
Posts: 988
Shadow wrote:
lyradmil wrote:
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix


C^{-1} may or may not exist depending on the diagonal matrix, D. Assuming D is invertible, then you just need to invert both sides and recall that (AB)^{-1}=B^{-1}A^{-1}


Like I said, "socks and shoes". I didn't want to do all the work for them! :wink:

_________________
"Mathematicians are like lovers. Grant a mathematician the least principle, and he will draw from it a consequence which you must also grant him, and from this consequence another." Bernard Le Bovier Fontenelle (1657-1757)

"In great mathematics there is a very high degree of unexpectedness, combined with inevitability and economy."
G.H. Hardy (1877-1947)
Top
 Profile  
 
Shadow
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Thu, 16 Feb 2012 21:26:43 UTC 
Online
Moderator
User avatar

Joined: Wed, 30 Mar 2005 04:25:14 UTC
Posts: 12074
Location: Austin, TX
Justin wrote:
Shadow wrote:
lyradmil wrote:
C=LDL^(-1). Find an expression for C^(-1), in terms of L, its inverse and some diagonal matrix


C^{-1} may or may not exist depending on the diagonal matrix, D. Assuming D is invertible, then you just need to invert both sides and recall that (AB)^{-1}=B^{-1}A^{-1}


Like I said, "socks and shoes". I didn't want to do all the work for them! :wink:


I don't get it, but OK.

_________________
(\ /)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination
Top
 Profile  
 
Voxx
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Fri, 2 Mar 2012 17:52:23 UTC 
Offline
Member

Joined: Tue, 20 Oct 2009 18:18:45 UTC
Posts: 33
Location: Lisbon, Portugal
when you dress: 1st, socks; 2nd shoes
when you undress («inverse»): 1st shoes, 2nd socks...
it's funny :)
Cheers
Voxx
Top
 Profile  
 
Shadow
 Post subject: Re: C=LDL^(-1). Find an expression for C^(-1).
PostPosted: Fri, 2 Mar 2012 17:56:33 UTC 
Online
Moderator
User avatar

Joined: Wed, 30 Mar 2005 04:25:14 UTC
Posts: 12074
Location: Austin, TX
Voxx wrote:
when you dress: 1st, socks; 2nd shoes
when you undress («inverse»): 1st shoes, 2nd socks...
it's funny :)
Cheers
Voxx


Ahhh, I see. Well put Voxx.

_________________
(\ /)
(O.o)
(> <)
This is Bunny. Copy Bunny into your signature to help him on his way to world domination
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  Page 1 of 1
  [ 8 posts ] 

Board index » High School and College Mathematics » Matrix Algebra

All times are UTC [ DST ]

Who is online

Users browsing this forum: No registered users

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Contact Us | S.O.S. Mathematics Homepage
Privacy Statement | Search the "old" CyberBoard

users online during the last hour
Powered by phpBB © 2001, 2005-2011 phpBB Group.
Copyright © 1999-2013 MathMedics, LLC. All rights reserved.
Math Medics, LLC. - P.O. Box 12395 - El Paso TX 79913 - USA