Re: JAMA successes (and troubles)

[Cleve Moler <moler@mathworks.com>]

On Thu, 13 Jun 2002, GILLIS  DARIN WAYNE wrote:

> 
> To whom it may concern:
> 
> I'm working on a Math Visualization tool in Java, and your JAMA package
> has been a great help in getting our project going.  But i have a few
> concerns with JAMA:
> 
> *there are single '&' all over the JAMA code
>  - it may speed things up to use double '&&' in the if statements
> 
> *I get ArrayIndexOutOfBounds errors for:
>  - LUDecomposition
>  - QRDecomposition
>  - SingularValueDecomposition
>   for *most if not all* m x n matrices where m < n.
> 
> Is there a solution for these troubles with the m < n decompositions?  If
> not, I just need to know before I start putting my own code in w/ the
> pre-existing JAMA code.
> 
> Any reply is appreciated,
> and Thank you for JAMA!
> ~Darin Gillis
> gillisd@colorado.edu
> 
> 

The documentation for JAMA clearly states that the rectangular
decompositions are intended only for matrices with m >= n.
Matrix problems with m < n usually require additional constraints,
but you can get a decomposition by transposing the matrix.

  -- Cleve Moler
  moler@mathworks.com