document that in general the surface-radius data is NOT contiguous in memory

and add a pointer to AEILocalInterp's option for supporting interpolation
of such data


git-svn-id: http://svn.cactuscode.org/arrangements/CactusNumerical/SphericalSurface/trunk@14 40f6ab95-0e4f-0410-8daa-ee8d7420be1d

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index ac6fd64..fa1b0b2 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -265,6 +265,19 @@ surfaces \texttt{lsh} instead.)  The surface array shape includes
 ghost or boundary zones at the array edges.  These ghost zones have
 the same size for all surfaces.
 
+Note that because the radius arrays are stored with larger size
+$\texttt{maxntheta} \times \texttt{maxnphi}$, the actual radius data
+(of size
+$\texttt{ntheta[surface\_number]} \times \texttt{nphi[surface\_number]}$
+elements) is in general {\em not contiguous in memory.\/}
+If you want to interpolate a SphericalSurface surface radius,
+you need to either copy the radius data to a contiguous 2-D array of size
+$\texttt{ntheta[surface\_number]} \times \texttt{nphi[surface\_number]}$,
+or use an interpolator which supports such non-contiguous input arrays.
+The AEIThorns/AEILocalInterp local interpolation thorn supports these
+via the \texttt{input\_array\_strides} parameter-table option.
+See the AEILocalInterp thorn guide for details.
+
 
 
 \section{Surface Symmetries}