Fix an incorrect parser error when trying to use cross-propagation on a non-uniformly spaced dimension.

git-svn-id: svn+ssh://svn.code.sf.net/p/xmds/code/trunk/xpdeint@2911 41b19578-b77a-4e3b-9682-c8570d237623
Refactoring the matrix transforms

git-svn-id: svn+ssh://svn.code.sf.net/p/xmds/code/trunk/xpdeint@2912 41b19578-b77a-4e3b-9682-c8570d237623
Add support for Hankel (Bessel) transforms with zero derivative boundary conditions at the outer boundary.

This commit adds a new transform "bessel-neumann".  This behaves like a normal "bessel" transform except that Neumann boundary conditions are applied at the outer boundary instead of Dirichlet boundary conditions.  It turns out that if f(r) obeys Neumann boundary conditions then so does f(kr).

This transform has only been tested with order="0", i.e. zero phase winding around the origin, but in principle, order="m" should work for any m > 0.

I've added an example bessel_neumann_wave_equation.xmds, a corresponding testcase, and some docs.

git-svn-id: svn+ssh://svn.code.sf.net/p/xmds/code/trunk/xpdeint@2913 41b19578-b77a-4e3b-9682-c8570d237623