Math::GSL-0.20

On MacBook Pro:

Architecture set incorrectly to -arch ppc when compiling some files due to Perl Config module. Can edit inc/GSLBuilder.pm to fix.

On G5 Tower:

my @include_dirs = @{$p->{include_dirs}} ...

needs to be

my @include_dirs = scalar(@{$p->{include_dirs}}) == 0 ...