Rank: 742 based on 189 downloads (last 30 days) and 1 file submitted
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Per Christian Hansen

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Company/University
Technical University of Denmark

Personal Profile:

Professor of Scientific Computing.
Research interests: inverse problems, matrix computations, signal processing.

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18 Mar 2008 Screenshot regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen linear algebra, discrete, illposed, regularization, mathematics 189 20
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4.7 | 26 ratings
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16 Apr 2014 regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen Palma, Carlos

Poorly documented. My own experience with it has been that I cannot know what matrices must I pass as arguments for these functions. For example when using l_corner I have found that you have to pass a matrix s, which I believe to be the matrix given by svd (nowhere it says whether this is right or wrong), and I always get an error because it tries to compute beta./s, with beta=U'*b, which in my case means beta is a 6x1 matrix, while s is a 6x6 matrix. How am I supposed to know how to solve this?, I'm just studying the basics of regularization!!!!!

09 Mar 2014 regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen Wong, kaiba

Very essential tools
I am trying the tikhonov function and getting errors...
suppose my Ax=b
A=matrix of 11375x3
b=vector of 11375x1
I calculated svd of A using svd(A,0)
assuming x_0 is zero
and insert lambda as [10,1,1e-2]
unfortunately..I keep getting an error that
Error in tikhonov (line 66)
if (nargin==6), omega = V\x_0; omega = omega(1:p); end

anyone having the same problem?...Thanks!

13 Feb 2014 regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen Thomas

Great package but, what is what...?

I have a data vector, and a model for calculating a theoretical data vector. What variables are the data vector and model in the call? Could someone lay out what each of these are?

tikhonov(U,s,V,b,lambda,x_0)
U=?
s=?
V=?
b=?
lambda=?
x_0=?

29 Oct 2013 regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen Feiyan

13 Aug 2013 regtools Analysis and Solution of Discrete Ill-Posed Problems. Author: Per Christian Hansen Ivanov, Andrey

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