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3.5 | 19 ratings Rate this file 37 Downloads (last 30 days) File Size: 1.08 KB File ID: #7779

LU Factorization by Doolittle's method

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03 Jun 2005 (Updated )

LU factorization of a square matrix.

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Description

This program factorize(decompose)the square matrix of any size into a product of a Lower-triangular matrix (L) and an Upper-triangular matrix (U). All the elements of the main diagonal in the L matrix are ones, (Doolittle's method).

This factorization is very helpfull in solving different mathematical problems and problems in linear control systems.

MATLAB release MATLAB 7 (R14)
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Comments and Ratings (23)
21 Jul 2013 PIAK

I want to algorithm for this program.

10 Aug 2011 abdullah alzkarneh

thx Dr.yaseen you are creative I hope many successes to you

26 Feb 2010 Husam Aldahiyat

No comments, messes workspace, C style programming. This file should be removed from the FEX.

31 Aug 2008 Peter Androv

Thanks, Excellent.

16 May 2008 noppanun suksomboon  
26 Jan 2008 Lara Evans

It was usefull for me.

16 Nov 2007 Tim Davis

See my comments below - I didn't select a rating in my last review.

03 Aug 2007 Muhammad Fahim

Nice

02 Jun 2007 Tim Davis

The file doesn't have any comments, so it isn't useful as an educational tool. The lutx.m function in Cleve Moler's NCM toolbox (http://www.mathworks.com/moler/ncmfilelist.html) is much better code (simpler, easier to read, and well commented). Plus, lutx.m comes with extensive documentation in Cleve's book which you can download for free. The file here has none of that.

Cleve even has an LU GUI in which you can watch the LU factorization, with pivoting, occur before your very eyes.

So for educational use, there are far far better alternatives.

Of course, for dense or sparse LU factorization this function (if it were converted into a function) would not be used in production code since it's far far slower
than the MATLAB built-in LU.

So why is it here? What purpose could it serve? Why does the File Exchange have a plethora of Gaussian Elimination variants such as this one?

I would kindly suggest that this file be withdrawn.

27 Apr 2007 amir khan

very good

12 Feb 2007 John Lee

This is an excellent program to explain the LU decomposition.

11 Nov 2006 Ahmad Warsy

i need this method to finish my thesis about dispatching

14 Apr 2006 Andres Fernandez

It seems written for visual basic, it doesn't use the Matrix Algebra MatLAB offers at all.

21 Jan 2006 John D'Errico

Why use a script that does an LU factorization in a completely unvectorized fashion? Especially when there is already a far faster implementation of an LU in matlab itself? Beware, this clears your workspace, then makes you type in the matrix. Its just the author's homework assignment.

18 Jan 2006 masoume azarpour  
05 Dec 2005 Duane Hanselman

Not a function. Clears the base workspace without warning! Poorly duplicates what the function LU does in MATLAB.

06 Nov 2005 Camilo Ardila  
08 Jun 2005 Alex Roberto  
06 Jun 2005 Dani Patrick  
06 Jun 2005 Hasan Ali  
06 Jun 2005 John Michael

Good, as showing the basics of decomposition

06 Jun 2005 Joseph Peter

Good For implenting Doolittle's method (the elements of the main diagonal are ones).

06 Jun 2005 Duane Hanselman

1) This is a script file, not a function.
2) Why use this function over the builtin MATLAB function LU?
3) Many For Loops in the script are not needed, e.g., you can start L with L=eye(m); rather than with a For Loop that does the same thing.
4) Does your code implement pivoting?
5) Nice homework solution for a beginning numerical methods class.

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