FINDELEMENTS Finds elements from the mesh

 USAGE:

       elements = findElements(vmcmesh, querystring, varargin)

 DESCRIPTION:

       This function can be used to find elements from the mesh.
       A complete description is given in the homepage (see below).

 INPUT:

       vmcmesh       - mesh structure, contains the geometry of the system

       querystring, optional arguments

       2D mesh (row size)

          'rectangle', position(2), width (1), height (1)
          'circle', location (2), radius (1)
          'inverse', elements (number of elements in the selection)
          'location', location (2)
          'region', region_BH (2)

       3D mesh (row size)

          'cylinder', origin (3), direction (3), radius (1)
          'box', origin (2), xsize (1), ysize (1), zsize (1)
          'sphere', location (3), radius (1)
          'inverse', elements (number of elements in the selection)
          'location', location (3)
          'region', region_BH (3)

 SEE ALSO:

 Detailed documentation of the function is given in
 https://inverselight.github.io/ValoMC/findingelements.html

 This function is provided with ValoMC