Returns a matrix that acts on a stretched pseudocontact shift density cube and projects out the values of the PCS at the Cartesian coordinates given. Tricubic interpolation is used. Syntax:
cube_dims - PCS cube dimensions, ordered as [X Y Z].
ranges - cartesian axis extents for the pseudocontact shift cube as [xmin xmax ymin ymax zmin zmax] in Angstroms.
xyz - nuclear coordinates as [x y z] with multiple rows) at which PCS is to be evaluated, in Angstroms.
P - matrix projecting out PCS values at the given positi- ons from the stretched PCS cube.
Note: this function is a part of the PCS inverse problem solver module and should not normally be called directly by the user.