Math::GSL : Perl <=> GNU Scientific Library

Grab the latest Math::GSL to get these spiffy features and bugfixes:

• Made Math::GSL play nice with latest and greatest GSL 1.12
• Added swap() to Vector objects with tests and docs
• Added p-norms to Vector objects via norm() and normalize()
• Added operator overloading so that

abs $vector == $vector->norm

• Added as_vector() to Matrix and MatrixComplex objects
• Added inverse(), is_square(), det(),  lndet(), zero() and identity() to Matrix objects
• Added inverse(), is_square(), det(),  lndet(), zero(), identity() and hermitian() to MatrixComplex objects
• Added dot product to Matrix objects
• Fixed various typos in documentation
• Fixed warnings about overloaded operators in Matrix and BLAS
• Overloaded '==' and '!=' for MatrixComplex and Matrix objects
• Fixed amd64 -fPIC compile failure
• Added tests to Monte and refactored Sort tests
• Refactored and improve error checking in callback interface
• Fixed 'NaN' test failures (thanks CPANtesters!)
  

Enjoy!

Math::GSL is still in active development and we have been working hard to make sure that it is compatible with the most recent GSL, which is 1.12 released on Dec 16 2008. This release is mostly for CPANTesters to see what bugs they can shake out of it, but it contains these tasty features:

• Make Math::GSL play nice with GSL 1.12
  
• Added swap() to Vector objects with tests and docs
• Added p-norms to Vector objects via norm() and normalize()
• Added operator overloading so that : abs $vector == $vector->norm
• Added as_vector() to Matrix and MatrixComplex objects
• Added inverse(), is_square(), det(),  lndet(), zero() and identity() to Matrix objects
• Added inverse(), is_square(), det(),  lndet(), zero(), identity() and hermitian() to MatrixComplex objects
• Added dot product to Matrix objects
• Fixed various typos in documentation
• Fixed warnings about overloaded operators in Matrix and BLAS

Enjoy!

The Matrix subsystem has really grown up in the last few days since the 0.16 release, including easy-to-use methods to calculate Matrix eigenvalues. All kinds of other methods are now available, like

my $det1 = $A->det;      # determinant
my $det2 = abs $A;       # determinant

my $inv = $A->inverse;  
my @eigs = $A->eigenvalues;

my ($eigenvalues, $eigenvectors) = $matrix->eigenpair;
my ($eig1,$eig2) = @$eigenvalues;
my ($u,$v)       = @$eigenvectors;

Compare this new script for calculating eigenvalues and eigenvectors of a nonsymmetric matrix to the old version. Yes, quite an improvement and quite pleasing to the eye now. Note that $A->eigenvalues; returns a list of Math::Complex objects because in general the eigenvalues of a real matrix can be complex. Only if your matrix is symmetric are you guaranteed real eigenvalues.

I haven't been able to add code to Math::GSL since about a month because of a tricky bug I had with the build process. Not only was it tricky, it was well hidden and pretty stupid to fix once I saw it.

Now that it's fixed I've been able to commit some code concerning overloading operators + and - in Math::GSL::Matrix. It's been tested and documented but it could still enjoy more documentation. End term exams are coming pretty fast to me so I won't finish overloading multiplication of matrices before one or two weeks.

Ho and Math::GSL 0.16 should be out soon, stay tuned!

I just pushed Math::GSL 0.15_05 to CPAN, which includes these fixes since 0.15_04 : 

After a question arose recently about finding complex eigenvalues of non-symmetric matrices, I wrote this example to show how it can be done with Math::GSL. The current example is called examples/matrix/nonsymmetric_eigen in the Math::GSL source, which will be in the 0.16 Math::GSL release. It uses the gsl_eigen_nonsymmv() function to do all the hard work, the rest is twiddling complex numbers. The documentation for this can be found with perldoc Math::GSL::Eigen or here.(The HTML rendering of the POD needs some work...) You can read the original C documentation for this function here.

I took a bit of a break after releasing Math::GSL 0.14 and tried not to stare at a screen too much  during the GSOC08 conference, when I could be interacting with open source developers from around the world IRL. I met developers from Git, Xmms2, VLC, PHP, Zikula, OpenAFS, Boost, Jikes RVM, Squeak, MusicBrainz, Worldforge, Minix3, the list goes on. People shared many ideas about making sustainable open source projects, getting and keeping members in your community and dealing with "troublesome" members.  Daniel Svensson from Xmms2 also showed me some git-fu relating to rebasing.