38th 2D example file, to illustrate the scattering option

Available only in the 'special' scattering version of CPO2D or CPO2DS.

The rays start at z = -0.8, in a field-free region.

Between z=-0.5 and z=0.5 the rays interact with the molecules of a background gas.

The routine that defines the scattering function is in file sct3back.cpp, which is supplied with the CPO3D package.  It should be copied to scatter2.cpp and used to create scatter2.dll, as explained in Help.

This routine calls the data file sct2back.dat (also supplied with the package), which is named by the User in the databuilder.

Please see sct2back.cpp for more detailed information.