Cewald: a C program for 3D data assembly

Anton Barty's Xewald program provides a beautiful way to interactively assemble 2D diffraction data into a 3D file. However, it would also be useful to have a C program to do this (we might call it Cewald, to be pronounced as ``See-walled''):

• As one gets to larger and larger data sets, it could be useful to build the 3D array on a parallel computer using MPI-enabled C language programs.
• It's possible that we will encounter a need for refinement of 2D file alignment in the future. One could imagine having a first 3D reconstruction which represents the best current guess of the object based on the totality of all 2D data files. One could then calculate the 3D diffraction intensity corresponding to this reconstruction, and then fit each 2D data file into it to find the best orientation, shift, and scaling for each file. This refinement program could write a .3da alignment text file (Sec. 2.3) that Cewald could then use to rebuild a 3D "/adi" file (Sec. 2.2.2).